Basicity Modification of the Yttrium oxide supported ruthenium nanoparticles catalysts to enhance catalytic performance for hydrogen production from ammonia decomposition

Basicity Modification of the Yttrium oxide supported ruthenium nanoparticles catalysts to enhance catalytic performance for hydrogen production from ammonia decomposition | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Basicity Modification of the Yttrium oxide supported ruthenium nanoparticles catalysts to enhance catalytic performance for hydrogen production from ammonia decomposition Ji Feng, Ningbo Wan, Xiaohua Ju, Lin Liu, Teng He, Liguang Bai, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7200571/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Hydrogen production from ammonia decomposition is a key green hydrogen preparation technology, and the supported ruthenium (Ru) catalyst is one of the most optimally active ammonia decomposition catalysts nowadays, and the basicity of the support has a significant effect on the performance of ruthenium catalysts. In this paper, a potassium-modified yyttrium support (K-Y 2 O 3 )-supported Ru nanoparticle catalyst was successfully prepared by the precipitation deposition method, and the hydrogen production rate of the 3% Ru/K-Y 2 O 3 catalyst was up to 31.49 mmol g cat −1 min − 1 under 450°C with a gas hour space velosity of 30,000 mL g cat −1 h − 1 , which was an order of magnitude higher than that of K-4.6% Ru/MgO catalyst. Moreover, the catalyst activity did not decay significantly during a 120 h test. Combined with TEM, NH 3 -TPD, XPS, CO 2 -TPD and other characterization methods, it was found that the presence of K species enhanced the basicity of the support, promoted the reduction of Ru nanoparticles and surface Y 2 O 3 supports, and increased the electron density of Ru nanoparticles and the oxygen vacancy concentration of the support, thus the Ru/K-Y 2 O 3 catalysts had strong ammonia dissociation and nitrogen-binding desorption ability to enhance its performance in ammonia decomposition reaction. ammonia decomposition Ru nanoparticles basicity oxygen vacancies electronic density Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction In recent years, the overuse of traditional energy sources such as coal, oil and natural gas has caused problems such as the rapid increase of greenhouse gases and the aggravation of environmental pollution, and the proton exchange membrane fuel cell technology has become a focal point for solving future environmental and energy problems. The three small molecules of energy that attract the most attention nowadays are methanol, ammonia and hydrogen. Although methanol fuel cells have the advantages of easy storage and transportation and wide source of raw materials, the by-product CO will cause serious poisoning to the Pt electrode and emit a large amount of CO 2 , which is essentially a non-green way of energy utilization. The ammonia synthesis technology based on the Harber-Bosch process has a hundred-year history and paves a way for the development of ammonia as an energy carrier, but the presence of NH 3 will cause serious damage to the membrane electrode system. Hydrogen fuel cell is one of the most promising technologies for on-board hydrogen utilization, but the lower volumetric energy density of hydrogen (8.96 GJ m -3 , while gasoline has 31.17 GJ m -3 ) and wider explosion limit (4~75%) make the storage and transportation process of hydrogen more difficult[1]. Ammonia, as an efficient carbon-free green hydrogen carrier with up to 17.6% hydrogen storage capacity, can be liquefied at room temperatures under 8 atm. and has a high volumetric energy density (13.6 GJ m -3 ) [2-4]. In addition, high purity hydrogen can be obtained by the Pd membrane separation system and the toxic effect of ammonia on the fuel cell system can also be avoided. Moreover, NH 3 has a strong odor and can be recognized by smell at concentrations below 5 ppm [5], which makes it quite safe to use. In general, the ammonia decomposition process is a endothermic reaction (NH 3 (g) = 1/2N 2 (g) + 3/2H 2 (g); Δ r =99.1 J/(mol·K), Δ r =46.1 kJ mol −1 ), and the equilibrium ammonia conversion can be as high as 99.2% or more at 400 °C [6], so it is crucial to develop efficient ammonia decomposition catalysts. The Ru catalyst is a low-temperature and highly efficient ammonia decomposition catalyst [7-11], and its ammonia decomposition performance strongly depends on the support composition and structure [12-15]. Molecular sieves [16, 17], carbon supports [8-11], metal oxide supports [5, 15, 18-22], composite supports [23-25], and electronic compound supports [14] are commonly used as supports for Ru-based catalysts. For example, Xu et al. [26] found that the ammonia decomposition activity of Ru-based catalysts supported on different supports followed the order: Ru/CNTs > Ru/MgO > Ru/TiO 2 ~ Ru/Al 2 O 3 ~ Ru/ZrO 2 > Ru/AC > Ru/ZrO 2 -BD, and the basicity and electrical conductivity of the support had a strong influence on the catalyst activity. Manabu et al. [27] found that doping of ZrO 2 support with rare earth metals enhanced the basicity of the support, and the TOF value of the ammonia decomposition reaction over the Ru catalyst increased significantly. Among them, the Ru/Sr(1)La(7)ZrO 2 catalyst demonstrated the best ammonia decomposition performance. Ju et al. [28] prepared a Ru/c-MgO ammonia decomposition catalyst enriched with basic sites by precipitation deposition method, and the hydrogen generation rate enhancement of Ru/c-MgO was close to three times as compared with that of Ru/MgO and Ru/CNTs catalysts. Yttrium oxide materials with easily modifiable structural composition, abundant defects and high stability have been developed as a common support for ammonia decomposition reactions in recent years. For example, Xu et al. [29] found that the Y 2 O 3 support could better disperse Ni nanoparticles, and the introduction of Al 2 O 3 can better avoid the agglomeration of Ni and Y 2 O 3 species during the reaction process, thus enhancing the stability of the ammonia decomposition reaction. Bao et al. [30] obtained Ni/Y 2 O 3 catalysts prepared by sol-gel method, and they found that by optimizing the ratio of Ni to Y species, the catalyst basicity can be improved, the electron transfer from the support to the Ni metal can be promoted, and the hydrogen poisoning effect of the catalyst can be improved. Xu et al. [31] prepared an atomically dispersed Ba species-modified Co/Y 2 O 3 catalyst with a hydrogen production rate of up to 138 mmol H2 g cat -1 min -1 under 500 °C with a GHSV of 840000 mL g cat -1 h -1 , and the activity did not show any significant decrease during the 350 h reaction. They found that the Y 2 O 3 support greatly facilitated the dispersion of Co and Ba species, the formation of the Co-O-Ba-Y 2 O 3 interface increased the charge density of metallic Co. Theoretical calculations verified that the formation of interfacial species drastically lowered the N-H bond cleavage energy barriers, which in turn enhanced the performance of the ammonia decomposition reaction. In addition, the results of previous studies by our group [32] demonstrated that strong metal-support interactions between Y 2 O 3 support and Ru nanoparticles would promote the dispersion of Ru and thus enhance the ammonia decomposition performance of Ru/Y 2 O 3 catalysts. Moreover, modulation of the precursor species of the Y 2 O 3 support could enhance the support basicity and further improve the metal-support interactions to increase the dispersion of Ru and the support oxygen vacancy concentration on the surface, thus promoting the dissociation of NH 3 and the binding desorption of N 2 [33]. Support basicity plays a very important role in the ammonia decomposition performance of Ru catalysts, here, we found that the introduction of suitable amount of potassium species can significantly enhance the Y 2 O 3 support basicity, further, to improve the interaction between Ru and Y 2 O 3 , to promote the reduction of Ru nanoparticles and surface support, and to enhance the ammonia decomposition reaction activity and stability. The NH 3 -TPD results showed that the 5% Ru/K-Y 2 O 3 catalyst had strong NH 3 dissociation and nitrogen binding desorption abilities. The findings of this study not only provide a reference for the design of efficient ammonia decomposition catalysts but also broaden the way for the application of Y 2 O 3 materials in heterogeneous catalytic reactions. Experimental Preparation of K-Y 2 O 3 supports K-Y 2 O 3 support was prepared by impregnation method, YCl 3 ·6H 2 O powder was dissolved in deionized water, and the pH was controlled to be about 7 with 1 mol L -1 (NH 4 ) 2 C 2 O 4 solution, and the powder of yttrium oxalate precursor was obtained by stirring, washing, filtration, and drying, and then the powder was impregnated with KOH solution for 1 h, and the K-Y 2 O 3 support can be obtained by drying and calcination at 800 °C for 4 h in a muffle furnace. Besides, 5% K-Y 2 O 3 and 10% K-Y 2 O 3 supports were obtained by controlling the amount of KOH. The contrast sample was obtained by using ammonia as the precipitant, controlling the pH of YCl 3 solution at 7~8, washing with deionized water, filtering, drying, and calcination at 800 °C for 4 h. Preparation of Ru catalysts The Ru catalysts were obtained by precipitation deposition method. 1 g the support powder was dispersed in 50 mL deionized water, 0.3 g K 2 CO 3 solid was added, and after ultrasonication pretreatment, 1 mL 81 mg mL -1 RuCl 3 solution was added, and the reaction was stirred for 1 h. After washing, filtration, and drying, the catalysts with a loading of 3% were obtained by reduction at 500 ℃ under NH 3 atmosphere. Characterizations X-ray powder diffraction (XRD) was carried out on an X'pert PRO type X-ray powder diffractometer (Panalytical). The N 2 physisorption was carried out on a QUADRASORB SI type physisorption instrument. The samples were degassed and evacuated at 300 °C prior to the test. The N 2 isothermal absorption and desorption curves of the samples were tested at the temperature of liquid nitrogen (-196 °C）. The specific surface area of the samples was calculated according to the Bmnauer-Emmet-Teller (BET) theory. Metal loadings were determined using Perkin-Elmer-Optima Model 7300DV inductively coupled plasma emission spectroscopy. Catalyst morphology and dimensional observations were performed on a FEI Talos F200X G2 transmission electron microscope equipped with an EDX for elemental composition analysis. H 2 temperature-programmed reduction (H 2 -TPR) was carried out in a fixed-bed reactor equipped with a gas chromatograph. In each run, 100 mg of catalyst was treated in a flowing stream of 10% H 2 /Ar stream with a flow rate of 30 mL min −1 and the programming temperature was ramped from room temperature to 800 °C with a ramping rate of 10 °C min −1 . The characterization of the oxygen vacancy concentration of the samples was performed using the electron paramagnetic resonance (EPR) technique, and the tests were analyzed on a Bruker EMXplus-6/1 device after a full reduction at 500 °C. X-ray photoelectron spectroscopy (XPS) was performed on a Thermo Scientific K-Alpha instrument. The light source was Al Kα (hν = 1486.6 eV), and the measured data were charge-corrected with C1s = 284.8 eV. The CO chemisorption test was performed on a Micromeritics Autochem III 2930 multifunctional chemisorption instrument. The samples were reduced at 350°C before the test, followed by Argon sweeping at the same temperature for 30 min, and then reduced to 50°C and adsorbed by introducing 10% CO/Ar. After the samples were saturated with adsorbed CO, the dispersion of Ru metal was calculated according to the ratio of Ru to CO of 1:1. The CO 2 -TPD test was performed on a Micromeritics Autochem III 2930 multifunctional chemisorbentimeter Before the test, the support was degassed in Ar gas at 150 ℃ for 1 h, reduced to 50 ℃ and introduced into CO 2 gas for 2 h. Ar was used to purge the CO 2 in the gas phase for 30 min, and finally the temperature was increased to 800 ℃ in Ar at a heating rate of 10 ℃/min, and the exhausted gas was introduced into the TCD detector to obtain the desorption signal of CO 2 . NH 3 -TPD was completed on a Hiden DECRA multifunctional chemisorbentimeter. Before the test, the oxidized catalyst was pre-reduced at 500 °C in 10% H 2 /Ar, cooled down to 50 °C and then introduced into 5% NH 3 /Ar adsorption for 30 min. Ar purge was used to remove NH 3 species physically adsorbed on the surface of the catalyst and the gas phase NH 3 , and finally the TPD curves were obtained by heating the catalysts to 800 °C in Ar at a temperature increase rate of 10 °C min -1 , and the signals of 28 (N 2 ), 17 (NH 3 ), and 2 (H 2 ) in MS were collected to obtain the TPD curves. Catalytic performance measurement Catalytic tests were carried out on a continuous fixed-bed flow quartz reactor under atmospheric pressure with a gas hourly space velocity (GHSV) of 30000 mL g cat −1 h −1 . The reaction temperature was in the range of 300~500 °C, and pure NH 3 was used as the only reactant. Product gas composition was analyzed by on-line gas chromatograph (GC–7890, Agilent) equipped with a thermal conductivity detector and Porapak N column with H 2 as carrier gas. Results and discussion Basic structural characterizations of Ru catalysts XRD techniques are commonly used to investigate the structural differences of Ru catalysts. Figure 1 demonstrates that 2theta angles of 29.3, 34.0, 48.8 and 57.9° correspond to the Y 2 O 3 (222), (400), (440) and (622) crystalline surfaces. As the content of potassium species in the support increases, no diffraction peaks of the potassium species are detected, which may imply high potassium species dispersion or poor crystallinity of the potassium species. In addition, to further investigate the effect of the presence of potassium species on the catalyst properties, N 2 isothermal adsorption and desorption curves were used to compare the differences in the specific surface area of the three catalysts. Combined with Figure S1(a), it can be found that the Ru/Y 2 O 3 , Ru/5% K-Y 2 O 3 , and Ru/10% K-Y 2 O 3 catalysts all exhibit a type IV isothermal adsorption line, which implies that all of them are nature as mesoporous materials. The specific surface areas of Ru/Y 2 O 3 , Ru/5% K-Y 2 O 3 and Ru/10% K-Y 2 O 3 catalysts were 52.3, 49.7 and 49.1 m 2 g -1 , respectively. Compared with the Ru/Y 2 O 3 material, the specific surface areas of Ru/5% K-Y 2 O 3 and Ru/10% K-Y 2 O 3 catalysts were slightly decreased, suggesting that the introduction of the K species might occupy part of the pores of the Y 2 O 3 support. It has been shown that the basicity of the support has a strong influence on the ammonia decomposition performance of Ru catalysts [23, 28, 34]. Here, the CO 2 -TPD technique was used to investigate the basicity of the catalysts, and according to the Figure S1(b) there was a clear CO 2 desorption peak of Y 2 O 3 before 330 °C, corresponding to a CO 2 desorption of about 0.1 mmol g cat -1 , and the CO 2 desorption of 5% K-Y 2 O 3 and 10% K-Y 2 O 3 supports at the same position was about 0.02 and 0.03 mmol g cat -1 (Table S1). In contrast, the 5% K-Y 2 O 3 and 10% K-Y 2 O 3 supports exhibited stronger CO 2 desorption signals after 330 °C, suggesting the stronger basicity of both, and the amount of CO 2 desorbed by Y 2 O 3 , 5% K-Y 2 O 3 and 10% K-Y 2 O 3 supports was about 0.27, 0.46, and 0.42 mmol g cat -1 after 330 °C (Table S1).The CO 2 -TPD results indicated that the introduction of potassium species could significantly enhance the number of basic sites of Y 2 O 3 support, which might have an effect on the properties of Ru species. Further, to investigate the effect of support basicity on the Ru status, TEM technique was used to probe the Ru/5% K-Y 2 O 3 catalyst morphology and size. From Figure 2(a), it can be found that the Ru/5% K-Y 2 O 3 catalyst exhibits a distinct nanoparticle shape, with the size distribution of the larger particles in the range of 100~120 nm and that of the smaller particles in the range of 10~30 nm. Combined with the EDX-Mapping results in Figure 2(b), most of the Ru particles are distributed on the surface of the small-sized supports, a few Ru particles are dispersed on the large-sized support surface, while potassium species are more uniformly distributed on all support surfaces, which is consistent with the results given by XRD. Meanwhile, the size of no less than 100 Ru nanoparticles was counted, and the inset of Figure (2) c demonstrates that the Ru size distribution of the reacted Ru/5% K-Y 2 O 3 catalysts was around 1.5~5 nm, and Table 1 demonstrates that the average Ru particle size of the Ru/5% K-Y 2 O 3 catalysts was about 2.9 nm. The insect of Figure (2) d demonstrates the Ru nanoparticle size statistics, the size distribution of Ru nanoparticles was around 1~4.5 nm, and Table 1 also demonstrated that the average size of Ru/Y 2 O 3 catalyst was 2.8 nm. Considering the limitation of the electron microscopy results, the average Ru nanoparticle size and dispersion of catalysts were calculated by the method of CO-chemisorption here. According to the results in Table 1, the Ru nanoparticle size of the Ru/5% K-Y 2 O 3 catalyst was about 4.2 nm and the metal dispersion was about 26.7%. The Ru nanoparticle size of the Ru/Y 2 O 3 catalyst was about 4.3 nm and the metal dispersion was about 23.2%. the CO-chemisorption results imply that the two catalysts are close to each other in terms of Ru size and dispersion. In addition, the XRD spectra (Figure 1) did not show obvious diffraction peaks attributed to Ru, indicating the high dispersion of metal Ru on the catalyst surface since the catalysts had been sufficiently reduced in an NH 3 atmosphere at 500 ゜C prior to test. Table 1 Properties of Ru/Y 2 O 3 and Ru/5% K-Y 2 O 3 (c) catalysts. Sample Surface area (m 2 g - 1 ) Loading of Ru (%) Contents of K (%) Ru particle size by TEM (nm) Metal dispersion by CO chemisorption (%) Ru particle size by CO chemisorption (nm) Ru/Y 2 O 3 52.3 2.9 - ~2.9 26.7 4.2 Ru/5% K-Y 2 O 3 49.7 2.8 3.4 ~2.8 23.2 4.3 Catalytic performances of Ru catalysts Figure 3(a) demonstrates the variation of ammonia decomposition reactivity of 5% K-Y 2 O 3 , Ru/Y 2 O 3 , Ru/5% K-Y 2 O 3 and Ru/10% K-Y 2 O 3 catalysts as a function of temperature, and the 5% K-Y 2 O 3 support has no ammonia decomposition reactivity under 450 °C with a GHSV of 30,000 mL g cat -1 h -1 , while the ammonia conversion of the Ru/Y 2 O 3 , Ru/5% K-Y 2 O 3 and Ru/10% K-Y 2 O 3 catalysts are 61.56%, 93.96% and 90.5%, and the hydrogen production rates are 20.56%, 93.96% and 90.5%, respectively. The hydrogen production rate of the Ru/5% K-Y 2 O 3 catalyst was 1.5 times higher than that of the Ru/Y 2 O 3 catalyst, which was equal to that of K-5% Ru/CNTs [8] in the literature, and 3.35, 3.58, and 1.23 times than that of 5% Ru/MgO [19], 5% Ru/AC [35], and 5% Ru/Y 2 O 3 [32] reported in the literature (seen in Table S2), implying the excellent ammonia decomposition reaction activity of the Ru/5% K-Y 2 O 3 catalyst. In addition, the stability of the catalyst is also critical in influencing the reaction performance. According to the results of Figure 3(b) the catalyst activity did not show any obvious change during the 120 h stability test, and the hydrogen production rate was stably maintained at 31.49 mmol g cat -1 min -1 , which also confirmed the excellent stability of the Ru/5% K-Y 2 O 3 catalyst. Here, the effect of GHSV on the activity was also analyzed, and it can be seen from Figure S2 that when the GHSV was increased from 8000 to 60,000 mL g cat -1 h -1 , the hydrogen production rates at different temperatures increased. Under 500 ℃ with a GHSV of 60,000 mL g cat -1 h -1 , the ammonia conversion of the Ru/5% K-Y 2 O 3 catalyst was still up to 94.64%, and the hydrogen production rate was up to 63.38 mmol g cat -1 min -1 , which showed excellent performance of hydrogen production from ammonia decomposition. Apparent activation energy is a key parameter reflecting the kinetic information of catalysts, and the activation energy of ammonia decomposition reaction is strongly dependent on the structural composition of the supports, the interactions between metal and supports, and the status of the Ru metal, therefore, the data of ammonia conversion in the range of about 10% to 30% are selected here, and the apparent activation energies of the Ru/Y 2 O 3 , Ru/5% K-Y 2 O 3 , and Ru/10% K-Y 2 O 3 catalysts were calculated, respectively. Combined with Figure 3(c), the apparent activation energies of Ru/Y 2 O 3 , Ru/5% K-Y 2 O 3 , and Ru/10% K-Y 2 O 3 catalysts were 87.5, 73.9, and 71.1 kJ mol -1 , respectively.Compared with the Ru/Y 2 O 3 catalysts, the apparent activation energies of Ru/5% K-Y 2 O 3 were significantly lower, which may imply that the enhancement of the basicity of the support had a strong influence on the Ru nanoparticles' properties. In addition, no significant decrease in the activation energy was observed with the increase of potassium species content. Moreover, the apparent activation energies of Ru/Y 2 O 3 [32], Ru/MgO [36], Ru/CNTs [36], Ru/AC [36], and Ru clusters/CeO 2 [37] catalysts in the literature were to be 90.4, 102.8, 86.5, 158.0, and 150.0 kJ mol -1 , respectively, which were higher than those of Ru/5% K-Y 2 O 3 , which may imply the efficient ammonia decomposition performance of the Ru/5% K-Y 2 O 3 catalyst.Turnover of frequency is also an important parameter that can influence the intrinsic activity of the catalysts, and combined with the results of the metal dispersion of CO chemisorption, the TOF value of the Ru/5% K-Y 2 O 3 catalyst can be obtained. From Figure 3(d), it can be found that the TOF value of the Ru/5% K-Y 2 O 3 catalyst is about 6.5 s -1 , and the intrinsic activity is much higher than that of the catalysts reported in the literature, such as 4.6% K-Ru-MgO [12] and 2.5% Ru/CNTs [12], which further demonstrated that the ultra-high intrinsic activity of the Ru/5% K-Y 2 O 3 catalyst. Studies on the Reduction Properties of Ru Catalyst To reveal the effect of support basicity on the reduction ability of the catalyst, the H 2 -TPR technique was used to probe the differences in the interactions between metal and supports. Figure 4(a) shows that Y 2 O 3 , a weakly reducible oxide, starts to be reduced at a temperature of about 600 °C, and the hydrogen consumption of the support is about 0.05 mmol g cat -1 (Table S3) based on the integral fitting of the peak area, whereas the Ru/Y 2 O 3 catalyst starts to be reduced at about 200 °C, and is fully reduced at about 500 °C, which corresponds to a hydrogen consumption of about 1.78 mmol g cat -1 (Table S3). The theoretical hydrogen consumption of the pure RuO 2 (RuO 3 ) species is about 0.59 (0.89) mmol g cat -1 , and the total hydrogen consumption of the ruthenium and yttrium oxides is still much lower than the actual hydrogen consumption of the catalysts. The change in reduction ability implies that the presence of Ru nanoparticles promotes the reduction of the surface supports and the presence of many overflow hydrogen species on the surface of the supports [38-41]. In contrast, for the Ru/5% K-Y 2 O 3 catalyst, the reduction of Ru nanoparticles occurred before 213 °C with a hydrogen consumption of about 0.3 mmol g cat -1 (Table S3), which is a decrease in the reduction temperature of the RuO x species for the Ru/5% K-Y 2 O 3 catalyst as compared to the Ru/Y 2 O 3 catalyst. The reduction peak between 213 °C and 472 °C implies the reduction of Ru nanoparticles and surface supports with a hydrogen consumption of about 1.24 mmol g cat -1 (Table S3), and the reduction peak after 472 °C implies the reduction of the supports and the presence of spillover hydrogen species, which occupies a hydrogen consumption of about 0.64 mmol g cat -1 (Table S3).The H 2 -TPR results demonstrate that the presence of potassium species promotes the reduction of Ru nanoparticles and supports. The XPS technique was used to probe the state of Ru species on the catalyst surface, combining with the previous report [42] that the peaks near 284.8 eV should be attributed to the overlapping signals of the Ru 3d 3/2 and C 1s shell layers, and the peaks near 280.4 eV should be attributed to the signals from the Ru 3d 5/2 shell layer. By comparing the signal peaks at the Ru 3d 5/2 position in Figure 4(b), it can be found that there is a difference in the Ru species valence states of the two catalyst, and the peaks centered around 281.7 eV may be attributed to the Ru n+ species [43, 44], and the peaks centered around 280.4 eV may correspond to the Ru 0 species [43, 45, 46]. The content of metallic Ru in both catalysts can be obtained by integrating the peak areas at different positions. For the Ru/5% K-Y 2 O 3 , the value of Ru 0 /(Ru n+ +Ru 0 ) is 84.1%, which is 2.8 times higher than that of the Ru/Y 2 O 3 catalyst (30.1%), implying that the presence of potassium species in the catalyst significantly facilitates the reduction of the RuO x species, in agreement with the results of H 2 -TPR. In addition, in combination with the valence electron spectra of O 1s in Figure 4(c), the peaks near 529 eV should belong to the lattice oxygen species (O L ) signals of the Y 2 O 3 support according to the results reported in the literature [24, 47, 48], whereas the peaks near 531 eV correspond to the signals of the molecular oxygen (O v ) adsorbed on the oxygen vacancies on the surface of Y 2 O 3 , and the peaks near 531~532 eV correspond to the signals of the Y 2 O 3 surface signal of hydroxyl oxygen (-OH). In general, the value of O v /(O v +O L ) can semi-quantify the content of oxygen vacancies in catalysts [42, 49], and by fitting the split peaks in Figure 4(c), the oxygen vacancy concentration of Ru/Y 2 O 3 and Ru/5% K-Y 2 O 3 catalysts were 36.7% and 57.3%, respectively, which confirmed the existence of a high concentration of oxygen vacancies on the surface of Ru/5% K-Y 2 O 3 catalysts. In addition to this, the electron paramagnetic resonance (EPR) technique has been used to study the properties of reduced catalysts in Figure 4(d). According to the literature results [50-52] the position of peaks with g values of 2.002~2.004 on the surface of metal oxides corresponds to the presence of oxygen vacancies. Under the same catalyst loading and testing conditions, combined with the analysis and comparison of the catalyst peak intensities and heights, the difference in the concentration of oxygen vacancies on the surface of the two catalysts can be obtained semi-quantitatively, and the height of the peaks of the Ru/5% K-Y 2 O 3 catalyst is 3.1 times higher than that of the Ru/Y 2 O 3 catalyst, implying an obvious difference in the concentration of the oxygen vacancies inside the two catalysts, which is in line with the results given by the XPS and the H 2 -TPR. Study of the adsorption and desorption processes of ammonia decomposition Previous studies [53-55] found that the dissociation of NH 3 and the binding desorption of N species on the surface of Ru nanoparticles may be the rate-determining step for the ammonia decomposition reaction. Therefore, to investigate the adsorption and desorption rules of the ammonia decomposition process on the surface of the Ru/5% K-Y 2 O 3 catalysts, the NH 3 -TPD technique was utilized to reveal the activation ability of the reactant molecules and the product molecules over Ru/5% K-Y 2 O 3 catalysts. Figure 5(a) illustrates that the onset temperature of nitrogen desorption over the Ru/5% K-Y 2 O 3 catalyst was around 400 °C, while that of the Ru/Y 2 O 3 catalyst was around 750 °C, implying that the reactive nitrogen species were more easily bound and desorbed on the surface of the Ru/5% K-Y 2 O 3 catalyst, which may be related to the stronger basicity of the Ru/5% K-Y 2 O 3 catalyst [23, 28, 34, 56]. In addition, Figure 5(b) also demonstrates the H 2 desorption signals on the surface of Ru/5% K-Y 2 O 3 and Ru/Y 2 O 3 catalysts, and both of catalysts have similar onset dehydrogenation temperatures around 700 °C, the Ru/5% K-Y 2 O 3 catalysts have stronger H 2 desorption signals, which implies that the surface of the Ru/5% K-Y 2 O 3 catalysts has more active hydrogen species. Further, according to Figure 5(c) the Ru/5% K-Y 2 O 3 catalyst showed a weak NH 3 desorption signal near 800 °C, whereas the Ru/Y 2 O 3 catalyst showed a stronger NH 3 desorption signal near 800 °C, implying a difference in the adsorption strength of NH 3 on the surface of the two catalysts. The NH 3 -TPD results demonstrated that the Ru/5% K-Y 2 O 3 catalyst supported a strong ammonia dissociation and nitrogen binding desorption ability. Conclusions In conclusion, in this paper, Ru/5% K-Y 2 O 3 catalysts with abundant basic sites were successfully prepared by the precipitation deposition method, which demonstrated a hydrogen production rate of 31.49 mmol g cat −1 min − 1 under 450 ℃ with a GHSV of 30,000 mL g cat −1 h − 1 , and remained stable over a long period of 120 h test. The relationship between support basicity and the reduction ability of Ru catalysts is demonstrated by TEM, H 2 -TPR, XPS and CO 2 -TPD characterization methods, and the presence of K species in the support promotes the reduction of Ru nanoparticles and the Y 2 O 3 , which promotes the formation of many oxygen vacancies. In addition, the NH 3 -TPD results confirmed the strong NH 3 dissociation and N 2 binding desorption ability of the Ru/5% K-Y 2 O 3 catalyst. The findings of this study may provide certain references for the design of efficient Ru-based ammonia decomposition catalysts and broaden the way for the application of the basic supports in heterogeneous catalytic reactions. Declarations Acknowledgements We acknowledge the financial support from the National Key Research and Development Program of China (2024YFB3815301), the Natural Science Foundation of China (22179128), and the Major Science and Technology Project of Liaoning Province (2024JH1/11700016). Author Contributions Ji Feng wrote the main manuscript text, Ningbo Wan help to complete the XRD, TEM, XPS and so on characterization results, all of authors reviewed the manuscript. Funding This work was supported by the National Key Research and Development Program of China (2024YFB3815301), the Natural Science Foundation of China (22179128), and the Major Science and Technology Project of Liaoning Province (2024JH1/11700016). Data Availability No datasets were generated or analyzed during the current study. Conflict of Interest The authors declare no competing interests. Ethics and Consent to Participate Not applicable. Consent for Publication Not applicable. References A. Zuttel, A. Remhof, A. Borgschulte, O. Friedrichs, Hydrogen: the future energy carrier, Philos Trans A Math Phys Eng Sci, 368 (2010) 3329-3342. T.M.I.M. Muhammad Heikal Hasan , M. Mofijur , I.M. Rizwanul Fattah ,, H.C.O.a.A.S.S. Fitri Handayani A Comprehensive Review on the Recent Development of Ammonia as a Renewable Energy Carrier, Energies, 14 (2021) 32. M. Aziz, A.T. Wijayanta, A.B.D. Nandiyanto, Ammonia as Effective Hydrogen Storage: A Review on Production, Storage and Utilization, Energies, 13 (2020). D.R. MacFarlane, P.V. Cherepanov, J. Choi, B.H.R. Suryanto, R.Y. Hodgetts, J.M. Bakker, F.M. Ferrero Vallana, A.N. Simonov, A Roadmap to the Ammonia Economy, Joule, 4 (2020) 1186-1205. I. Lucentini, A. Casanovas, J. 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Dolan, Ammonia decomposition kinetics over LiOH-promoted, α-Al2O3-supported Ru catalyst, International Journal of Hydrogen Energy, 44 (2019) 3726-3736. Additional Declarations No competing interests reported. Supplementary Files SupportingInformation20250724.doc Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7200571","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":501306166,"identity":"5b34b9b6-ecef-4bdd-a2c4-62013a4b366b","order_by":0,"name":"Ji Feng","email":"","orcid":"","institution":"Liming Chemical Research and Design Institute Co., Ltd","correspondingAuthor":false,"prefix":"","firstName":"Ji","middleName":"","lastName":"Feng","suffix":""},{"id":501306167,"identity":"fe6ef666-39af-4734-8f79-cf48d7f25255","order_by":1,"name":"Ningbo Wan","email":"","orcid":"","institution":"Henan University of Science and 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samples.\u003c/p\u003e","description":"","filename":"floatimage3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7200571/v1/a1af456bacee061b05d858c7.jpeg"},{"id":89299006,"identity":"068afcba-672c-4b3c-9ca8-ff7a3cf17ed3","added_by":"auto","created_at":"2025-08-18 14:04:03","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":5636398,"visible":true,"origin":"","legend":"\u003cp\u003eTEM dark field image (a) and overlapping of O, K, Y, Ru elemental maps (b) for reduced Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e sample, TEM images and Ru size distribution of reduced Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e sample (c and inset), TEM images and Ru size distribution of reduced Ru/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e sample (d and insect).\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-7200571/v1/0b7c04d9d512c87597045732.png"},{"id":89299005,"identity":"770a8223-8eff-444a-8fdc-80dae2d7f011","added_by":"auto","created_at":"2025-08-18 14:04:03","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":2550916,"visible":true,"origin":"","legend":"\u003cp\u003e(a) NH\u003csub\u003e3\u003c/sub\u003e conversion over 5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, Ru/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e and Ru/10% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalysts as a function of reaction temperature. (b) Stability test of Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst for NH\u003csub\u003e3\u003c/sub\u003e decomposition at 450 °C with a GHSV of 30000 mL g\u003csub\u003ecat\u003c/sub\u003e\u003csup\u003e−1\u003c/sup\u003e h\u003csup\u003e−1\u003c/sup\u003e. (c) Arrhenius plots of Ru/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e and Ru/10% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalysts. (d) A comparison of TOF\u003csub\u003eH2\u003c/sub\u003e values at 450 °C of 2.8% Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e and typical efficient Ru-based NH\u003csub\u003e3\u003c/sub\u003e decomposition catalysts reported in literatures.\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-7200571/v1/0c80446f4ab720da4219f020.png"},{"id":89297777,"identity":"98341cfa-22d8-478f-ae18-2dadc987e776","added_by":"auto","created_at":"2025-08-18 13:48:03","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":2744305,"visible":true,"origin":"","legend":"\u003cp\u003e(a) TPR profiles of Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, Ru/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e and Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e samples, (b) Ru 3d and C 1s core levels XPS spectra of Ru/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e and Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e samples, (c) O 1s core levels XPS spectra of Ru/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e and Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e samples, (d) EPR profiles of Ru/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e and Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e samples.\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-7200571/v1/f5aa0989bcd4c5b482ba8fe1.png"},{"id":89297775,"identity":"fe74d0b4-06d2-4ae4-98a5-1a45a8eba364","added_by":"auto","created_at":"2025-08-18 13:48:03","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":103565,"visible":true,"origin":"","legend":"\u003cp\u003eNH\u003csub\u003e3\u003c/sub\u003e-TPD profiles of Ru/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e and Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e samples, and signal data was collected under He with a heating rate of 10 ℃ min\u003csup\u003e‒1\u003c/sup\u003e: N\u003csub\u003e2\u003c/sub\u003e (a); H\u003csub\u003e2\u003c/sub\u003e (b); NH\u003csub\u003e3\u003c/sub\u003e (c).\u003c/p\u003e","description":"","filename":"floatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-7200571/v1/abcda7cf2f7aec03ea0373ea.png"},{"id":91127647,"identity":"d5d44ec4-d127-45c1-844e-639b02a02b48","added_by":"auto","created_at":"2025-09-11 22:31:20","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":12066262,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7200571/v1/19614f44-e775-4470-afeb-63937d58d827.pdf"},{"id":89297779,"identity":"535111f4-c681-45e6-a2a0-df92308fe755","added_by":"auto","created_at":"2025-08-18 13:48:03","extension":"doc","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":1150976,"visible":true,"origin":"","legend":"","description":"","filename":"SupportingInformation20250724.doc","url":"https://assets-eu.researchsquare.com/files/rs-7200571/v1/5a12156db71abb079766009d.doc"}],"financialInterests":"No competing interests reported.","formattedTitle":"Basicity Modification of the Yttrium oxide supported ruthenium nanoparticles catalysts to enhance catalytic performance for hydrogen production from ammonia decomposition","fulltext":[{"header":"Introduction","content":"\u003cp\u003eIn recent years, the overuse of traditional energy sources such as coal, oil and natural gas has caused problems such as the rapid increase of greenhouse gases and the aggravation of environmental pollution, and the proton exchange membrane fuel cell technology has become a focal point for solving future environmental and energy problems. The three small molecules of energy that attract the most attention nowadays are methanol, ammonia and hydrogen. Although methanol fuel cells have the advantages of easy storage and transportation and wide source of raw materials, the by-product CO will cause serious poisoning to the Pt electrode and emit a large amount of CO\u003csub\u003e2\u003c/sub\u003e, which is essentially a non-green way of energy utilization. The ammonia synthesis technology based on the Harber-Bosch process has a hundred-year history and paves a way for the development of ammonia as an energy carrier, but the presence of NH\u003csub\u003e3\u003c/sub\u003e will cause serious damage to the membrane electrode system. Hydrogen fuel cell is one of the most promising technologies for on-board hydrogen utilization, but the lower volumetric energy density of hydrogen (8.96 GJ m\u003csup\u003e-3\u003c/sup\u003e , while gasoline has 31.17 GJ m\u003csup\u003e-3\u003c/sup\u003e ) and wider explosion limit (4~75%) make the storage and transportation process of hydrogen more difficult[1].\u003c/p\u003e\n\u003cp\u003eAmmonia, as an efficient carbon-free green hydrogen carrier with up to 17.6% hydrogen storage capacity, can be liquefied at room temperatures under 8 atm. and has a high volumetric energy density (13.6 GJ m\u003csup\u003e-3\u003c/sup\u003e) [2-4]. In addition, high purity hydrogen can be obtained by the Pd membrane separation system and the toxic effect of ammonia on the fuel cell system can also be avoided. Moreover, NH\u003csub\u003e3\u003c/sub\u003e has a strong odor and can be recognized by smell at concentrations below 5 ppm [5], which makes it quite safe to use. In general, the ammonia decomposition process is a endothermic reaction (NH\u003csub\u003e3\u003c/sub\u003e (g) = 1/2N\u003csub\u003e2\u003c/sub\u003e (g) + 3/2H\u003csub\u003e2\u003c/sub\u003e (g); \u0026Delta;\u003csub\u003er\u003c/sub\u003e\u003cimg width=\"15\" height=\"21\" src=\"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABYAAAAfCAYAAADjuz3zAAAAAXNSR0IArs4c6QAAAAlwSFlzAAAWJQAAFiUBSVIk8AAAABl0RVh0U29mdHdhcmUATWljcm9zb2Z0IE9mZmljZX/tNXEAAAVSSURBVEhL7ZV5UFNXFMa/kBfIQCIBDYHaIJGlyrApIESgrhTqMmARq0IRhCqOlg6DM46A0TwEUVuk1UqrVQvqaK22VdwFlApuARFkExAEEtkJOySQpA+XjnSYEZxxpn/0/vXevef+7pnv3O8eQiwW430M4n1Ah5n/g/9R9r8lhUgkogOHdJxo65E/nOPCGxB73Ol78yK8Y8bVYU0ZzcE8AWioITQWrGpNRt+abQt1UzNfw8cFpjLVAkojK37+fmPOoy6Bs/gYfBQtaLxbC9pU6S791aJvO5LIX8d93UiSVEcvZ/g8aFIJ4i/T8rbvDC4K4khXZBdFsSoNac6dwMcUdCSYysYcKLYVz3PEjltKGhXABvhKCL8ccFxpI8uLWFYGVAmf7fFnl7Ej0BMecimIg++Apk96u3ksZbca+gz09r7S4oUUFHSKuu1RbEV5XrBs8kLYzGxAzZOK2onaKq6ZLUe3WWWcDgxthrIt+UmjtrW0PR9cPscqNPSUV6CfI/NmMQt2vqaw1YH2hTfBUMv21F/7ZVnc8VI8XxQHUsSrbci4HGJfvHVFibN2SHyreRelLSB7wCh8poXMv85Brj7tVd7Z5pJ55aZBBy8UicaG/TZA10hwV+4Hj/PkDLlyJoQLXEo8rbA26XTrA7eArhLmIONwf7ORHLhIU/YPEHLDT7Eyyh42U3puXI8PvOgx2/jgJTN3drqUmRjugiMjbwVTW4tJ60d9WTXYsl5ui7VeICVPJUmiGZA2bwJJxXPM1RqCo2YJYDbDC8HezOlzUY7jtxt0lnzmim46UUEVV/YvMP/gR/P5en5V+fY/REcY7WkO+8rXU8im4FQsWfMyuL+NoGuTFkOSmOr04klxj9h2aqaF3ZDDYvAMtI5+bozS/W845EXxSPLSSZHIa2A9XT9m4MfMGem7tkBVtzO4zc9paINIdCCFJAtJUtEBKJKX0nOInKtFTmkVKpiGHsSBba7dS42xlUqgdVTnkeS9c1SGPQkOjsm20TGWu+Ji6fpmR8JM+JZU4RD1elP6RN9vzAN88bI9tKAglUTBKI/6COdRp14TiTaE+oo3pTeW7jUszyvC7w6WNO4oG982NYqluXIdjr6GxaRBpVCgdxCqdwK7Pt/+50m7K0gz8E7UrAKl48OUwozLE9LKuJj1hT2EphhYIRJYdebk7YzffZyxl9gMct4UmmNGLFand2oG58fgfHgzJPsPIPq2NqZ7JSD56gYQZoYWPgb3/gDr9u6ps/b19vj7uAvbpTw4hK+FhcPk804cXGgpMLDgmrj7Lw4axJ2UGsgaLeAZlYAdZhdwNSsT154KMS0iEmt0KjGkJKBH6UTUyvmpnecPgegCS/IMWhLJw9RZHj9hx9ce8JyGpASSLFpuOcdW8aHqNyuB6SKBbqVeZm57rm/CyoEQA/mCmqwz6OO4wXm5JXiVp5B1a/CF/MRdk7nBgqi5iBxRDRkkZ0hIXs2drcx+LNq4Paxwi3Xh0HyxXlW2W5K3fFVjSZ37gnrXjaoAoWOxXfd1IwldZdLhbI0pHe1j69Ii0WxmBWeJ7dOC/Aku/uaY5GtiPnBSqi9nNEDj5KPcV6+/zu9+1Noh3XXr+3QM0Vn4ZGxgwMCJPcf/aNUJPktvCaHZMhWRDZMCVOXZtRqHoMmddbZox+Gurtb7NzS5z/uQZhk4VjCegqET29M2rYelpquNAL06hiFN3tbQw+exFW4sNEFnwjFFXU2WtIKDYoI7NjBl+QZK7jPEGqC17CwSh9+k4WEzEdITCZBSn3cQVkZ4o0zsTf3cSxkb+G0uG219XM10PAe8N/DfnM4gpBhHMfAAAAAASUVORK5CYII=\" alt=\"image\"\u003e=99.1 J/(mol\u0026middot;K), \u0026Delta;\u003csub\u003er\u003c/sub\u003e\u003cimg width=\"17\" height=\"21\" src=\"data:image/png;base64,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\" alt=\"image\"\u003e=46.1 kJ mol\u003csup\u003e\u0026minus;1\u003c/sup\u003e), and the equilibrium ammonia conversion can be as high as 99.2% or more at 400 \u0026deg;C [6], so it is crucial to develop efficient ammonia decomposition catalysts.\u003c/p\u003e\n\u003cp\u003eThe Ru catalyst is a low-temperature and highly efficient ammonia decomposition catalyst [7-11], and its ammonia decomposition performance strongly depends on the support composition and structure [12-15]. Molecular sieves [16, 17], carbon supports [8-11], metal oxide supports [5, 15, 18-22], composite supports [23-25], and electronic compound supports [14] are commonly used as supports for Ru-based catalysts. For example, Xu et al. [26] found that the ammonia decomposition activity of Ru-based catalysts supported on different supports followed the order: Ru/CNTs \u0026gt; Ru/MgO \u0026gt; Ru/TiO\u003csub\u003e2\u003c/sub\u003e ~ Ru/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e ~ Ru/ZrO\u003csub\u003e2\u003c/sub\u003e \u0026gt; Ru/AC \u0026gt; Ru/ZrO\u003csub\u003e2\u003c/sub\u003e-BD, and the basicity and electrical conductivity of the support had a strong influence on the catalyst activity. Manabu et al. [27] found that doping of ZrO\u003csub\u003e2\u003c/sub\u003e support with rare earth metals enhanced the basicity of the support, and the TOF value of the ammonia decomposition reaction over the Ru catalyst increased significantly. Among them, the Ru/Sr(1)La(7)ZrO\u003csub\u003e2\u003c/sub\u003e catalyst demonstrated the best ammonia decomposition performance. Ju et al. [28] prepared a Ru/c-MgO ammonia decomposition catalyst enriched with basic sites by precipitation deposition method, and the hydrogen generation rate enhancement of Ru/c-MgO was close to three times as compared with that of Ru/MgO and Ru/CNTs catalysts.\u003c/p\u003e\n\u003cp\u003eYttrium oxide materials with easily modifiable structural composition, abundant defects and high stability have been developed as a common support for ammonia decomposition reactions in recent years. For example, Xu et al. [29] found that the Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e support could better disperse Ni nanoparticles, and the introduction of Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e can better avoid the agglomeration of Ni and Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e species during the reaction process, thus enhancing the stability of the ammonia decomposition reaction. Bao et al. [30] obtained Ni/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalysts prepared by sol-gel method, and they found that by optimizing the ratio of Ni to Y species, the catalyst basicity can be improved, the electron transfer from the support to the Ni metal can be promoted, and the hydrogen poisoning effect of the catalyst can be improved. Xu et al. [31] prepared an atomically dispersed Ba species-modified Co/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst with a hydrogen production rate of up to 138 mmol\u003csub\u003eH2\u003c/sub\u003e g\u003csub\u003ecat\u003c/sub\u003e\u003csup\u003e-1\u003c/sup\u003e min\u003csup\u003e-1\u003c/sup\u003e under 500 \u0026deg;C with a GHSV of 840000 mL g\u003csub\u003ecat\u003c/sub\u003e\u003csup\u003e-1\u003c/sup\u003e h\u003csup\u003e-1\u003c/sup\u003e, and the activity did not show any significant decrease during the 350 h reaction. They found that the Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e support greatly facilitated the dispersion of Co and Ba species, the formation of the Co-O-Ba-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e interface increased the charge density of metallic Co. Theoretical calculations verified that the formation of interfacial species drastically lowered the N-H bond cleavage energy barriers, which in turn enhanced the performance of the ammonia decomposition reaction. In addition, the results of previous studies by our group [32] demonstrated that strong metal-support interactions between Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e support and Ru nanoparticles would promote the dispersion of Ru and thus enhance the ammonia decomposition performance of Ru/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalysts. Moreover, modulation of the precursor species of the Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e support could enhance the support basicity and further improve the metal-support interactions to increase the dispersion of Ru and the support oxygen vacancy concentration on the surface, thus promoting the dissociation of NH\u003csub\u003e3 \u003c/sub\u003eand the binding desorption of N\u003csub\u003e2\u003c/sub\u003e [33].\u003c/p\u003e\n\u003cp\u003eSupport basicity plays a very important role in the ammonia decomposition performance of Ru catalysts, here, we found that the introduction of suitable amount of potassium species can significantly enhance the Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e support basicity, further, to improve the interaction between Ru and Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, to promote the reduction of Ru nanoparticles and surface support, and to enhance the ammonia decomposition reaction activity and stability. The NH\u003csub\u003e3\u003c/sub\u003e-TPD results showed that the 5% Ru/K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst had strong NH\u003csub\u003e3\u003c/sub\u003e dissociation and nitrogen binding desorption abilities. The findings of this study not only provide a reference for the design of efficient ammonia decomposition catalysts but also broaden the way for the application of Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e materials in heterogeneous catalytic reactions.\u003c/p\u003e"},{"header":"Experimental","content":"\u003cp\u003e\u003cstrong\u003ePreparation of K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e supports\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eK-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e support was prepared by impregnation method, YCl\u003csub\u003e3\u003c/sub\u003e\u0026middot;6H\u003csub\u003e2\u003c/sub\u003eO powder was dissolved in deionized water, and the pH was controlled to be about 7 with 1 mol L\u003csup\u003e-1\u003c/sup\u003e (NH\u003csub\u003e4\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003eC\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e solution, and the powder of yttrium oxalate precursor was obtained by stirring, washing, filtration, and drying, and then the powder was impregnated with KOH solution for 1 h, and the K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e support can be obtained by drying and calcination at 800 \u0026deg;C for 4 h in a muffle furnace. Besides, 5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e and 10% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e supports were obtained by controlling the amount of KOH.\u003c/p\u003e\n\u003cp\u003eThe contrast sample was obtained by using ammonia as the precipitant, controlling the pH of YCl\u003csub\u003e3\u003c/sub\u003e solution at 7~8, washing with deionized water, filtering, drying, and calcination at 800 \u0026deg;C for 4 h.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePreparation of Ru catalysts\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe Ru catalysts were obtained by precipitation deposition method. 1 g the support powder was dispersed in 50 mL deionized water, 0.3 g K\u003csub\u003e2\u003c/sub\u003eCO\u003csub\u003e3\u003c/sub\u003e solid was added, and after ultrasonication pretreatment, 1 mL 81 mg mL\u003csup\u003e-1\u003c/sup\u003e RuCl\u003csub\u003e3\u003c/sub\u003e solution was added, and the reaction was stirred for 1 h. After washing, filtration, and drying, the catalysts with a loading of 3% were obtained by reduction at 500\u0026nbsp;℃ under NH\u003csub\u003e3\u003c/sub\u003e atmosphere.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCharacterizations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eX-ray powder diffraction (XRD) was carried out on an X\u0026apos;pert PRO type X-ray powder diffractometer (Panalytical).\u003c/p\u003e\n\u003cp\u003eThe N\u003csub\u003e2\u003c/sub\u003e physisorption was carried out on a QUADRASORB SI type physisorption instrument. The samples were degassed and evacuated at 300 \u0026deg;C prior to the test. The N\u003csub\u003e2\u003c/sub\u003e isothermal absorption and desorption curves of the samples were tested at the temperature of liquid nitrogen (-196 \u0026deg;C）. The specific surface area of the samples was calculated according to the Bmnauer-Emmet-Teller (BET) theory.\u003c/p\u003e\n\u003cp\u003eMetal loadings were determined using Perkin-Elmer-Optima Model 7300DV inductively coupled plasma emission spectroscopy.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eCatalyst morphology and dimensional observations were performed on a FEI Talos F200X G2 transmission electron microscope equipped with an EDX for elemental composition analysis.\u003c/p\u003e\n\u003cp\u003eH\u003csub\u003e2\u003c/sub\u003e temperature-programmed reduction (H\u003csub\u003e2\u003c/sub\u003e-TPR) was carried out in a fixed-bed reactor equipped with a gas chromatograph. In each run, 100 mg of catalyst was treated in a flowing stream of 10% H\u003csub\u003e2\u003c/sub\u003e/Ar stream with a flow rate of 30 mL min\u003csup\u003e\u0026minus;1\u003c/sup\u003e and the programming temperature was ramped from room temperature to 800 \u0026deg;C with a ramping rate of 10 \u0026deg;C min\u003csup\u003e\u0026minus;1\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eThe characterization of the oxygen vacancy concentration of the samples was performed using the electron paramagnetic resonance (EPR) technique, and the tests were analyzed on a Bruker EMXplus-6/1 device after a full reduction at 500 \u0026deg;C.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eX-ray photoelectron spectroscopy (XPS) was performed on a Thermo Scientific K-Alpha instrument. The light source was Al K\u0026alpha; (h\u0026nu; = 1486.6 eV), and the measured data were charge-corrected with C1s = 284.8 eV.\u003c/p\u003e\n\u003cp\u003eThe CO chemisorption test was performed on a Micromeritics Autochem III 2930 multifunctional chemisorption instrument. The samples were reduced at 350\u0026deg;C before the test, followed by Argon sweeping at the same temperature for 30 min, and then reduced to 50\u0026deg;C and adsorbed by introducing 10% CO/Ar. After the samples were saturated with adsorbed CO, the dispersion of Ru metal was calculated according to the ratio of Ru to CO of 1:1.\u003c/p\u003e\n\u003cp\u003eThe CO\u003csub\u003e2\u003c/sub\u003e-TPD test was performed on a Micromeritics Autochem III 2930 multifunctional chemisorbentimeter \u0026nbsp;Before the test, the support was degassed in Ar gas at 150 ℃ for 1 h, reduced to 50 ℃ and introduced into CO\u003csub\u003e2\u003c/sub\u003e gas for 2 h. Ar was used to purge the CO\u003csub\u003e2\u003c/sub\u003e in the gas phase for 30 min, and finally the temperature was increased to 800 ℃ in Ar at a heating rate of 10 ℃/min, and the exhausted gas was introduced into the TCD detector to obtain the desorption signal of CO\u003csub\u003e2\u003c/sub\u003e.\u003c/p\u003e\n\u003cp\u003eNH\u003csub\u003e3\u003c/sub\u003e-TPD was completed on a Hiden DECRA multifunctional chemisorbentimeter. Before the test, the oxidized catalyst was pre-reduced at 500 \u0026deg;C in 10% H\u003csub\u003e2\u003c/sub\u003e/Ar, cooled down to 50 \u0026deg;C and then introduced into 5% NH\u003csub\u003e3\u003c/sub\u003e/Ar adsorption for 30 min. Ar purge was used to remove NH\u003csub\u003e3\u003c/sub\u003e species physically adsorbed on the surface of the catalyst and the gas phase NH\u003csub\u003e3\u003c/sub\u003e, and finally the TPD curves were obtained by heating the catalysts to 800 \u0026deg;C in Ar at a temperature increase rate of 10 \u0026deg;C min\u003csup\u003e-1\u003c/sup\u003e, and the signals of 28 (N\u003csub\u003e2\u003c/sub\u003e), 17 (NH\u003csub\u003e3\u003c/sub\u003e), and 2 (H\u003csub\u003e2\u003c/sub\u003e) in MS were collected to obtain the TPD curves.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCatalytic performance measurement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCatalytic tests were carried out on a continuous fixed-bed flow quartz reactor under atmospheric pressure with a gas hourly space velocity (GHSV) of 30000 mL g\u003csub\u003ecat\u003c/sub\u003e\u003csup\u003e\u0026minus;1\u003c/sup\u003e h\u003csup\u003e\u0026minus;1\u003c/sup\u003e. The reaction temperature was in the range of 300~500 \u0026deg;C, and pure NH\u003csub\u003e3\u003c/sub\u003e was used as the only reactant. Product gas composition was analyzed by on-line gas chromatograph (GC\u0026ndash;7890, Agilent) equipped with a thermal conductivity detector and Porapak N column with H\u003csub\u003e2\u003c/sub\u003e as carrier gas.\u003c/p\u003e"},{"header":"Results and discussion","content":"\u003cp\u003e\u003cstrong\u003eBasic structural characterizations of Ru catalysts\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eXRD techniques are commonly used to investigate the structural differences of Ru catalysts. Figure 1 demonstrates that 2theta angles of 29.3, 34.0, 48.8 and 57.9\u0026deg; correspond to the Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e (222), (400), (440) and (622) crystalline surfaces. As the content of potassium species in the support increases, no diffraction peaks of the potassium species are detected, which may imply high potassium species dispersion or poor crystallinity of the potassium species. In addition, to further investigate the effect of the presence of potassium species on the catalyst properties, N\u003csub\u003e2\u003c/sub\u003e isothermal adsorption and desorption curves were used to compare the differences in the specific surface area of the three catalysts. Combined with Figure S1(a), it can be found that the Ru/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, and Ru/10% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalysts all exhibit a type IV isothermal adsorption line, which implies that all of them are nature as mesoporous materials. The specific surface areas of Ru/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e and Ru/10% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalysts were 52.3, 49.7 and 49.1 m\u003csup\u003e2\u003c/sup\u003e g\u003csup\u003e-1\u003c/sup\u003e, respectively. Compared with the Ru/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e material, the specific surface areas of Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e and Ru/10% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalysts were slightly decreased, suggesting that the introduction of the K species might occupy part of the pores of the Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e support. It has been shown that the basicity of the support has a strong influence on the ammonia decomposition performance of Ru catalysts [23, 28, 34]. Here, the CO\u003csub\u003e2\u003c/sub\u003e-TPD technique was used to investigate the basicity of the catalysts, and according to the Figure S1(b) there was a clear CO\u003csub\u003e2\u003c/sub\u003e desorption peak of Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e before 330 \u0026deg;C, corresponding to a CO\u003csub\u003e2\u003c/sub\u003e desorption of about 0.1 mmol g\u003csub\u003ecat\u003c/sub\u003e\u003csup\u003e-1\u003c/sup\u003e, and the CO\u003csub\u003e2\u003c/sub\u003e desorption of 5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e and 10% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e supports at the same position was about 0.02 and 0.03 mmol g\u003csub\u003ecat\u003c/sub\u003e\u003csup\u003e-1\u003c/sup\u003e (Table S1). In contrast, the 5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e and 10% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e supports exhibited stronger CO\u003csub\u003e2\u003c/sub\u003e desorption signals after 330 \u0026deg;C, suggesting the stronger basicity of both, and the amount of CO\u003csub\u003e2\u003c/sub\u003e desorbed by Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, 5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e and 10% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e supports was about 0.27, 0.46, and 0.42 mmol g\u003csub\u003ecat\u003c/sub\u003e\u003csup\u003e-1\u003c/sup\u003e after 330 \u0026deg;C (Table S1).The CO\u003csub\u003e2\u003c/sub\u003e -TPD results indicated that the introduction of potassium species could significantly enhance the number of basic sites of Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e support, which might have an effect on the properties of Ru species.\u003c/p\u003e\n\u003cp\u003eFurther, to investigate the effect of support basicity on the Ru status, TEM technique was used to probe the Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst morphology and size. From Figure 2(a), it can be found that the Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst exhibits a distinct nanoparticle shape, with the size distribution of the larger particles in the range of 100~120 nm and that of the smaller particles in the range of 10~30 nm. Combined with the EDX-Mapping results in Figure 2(b), most of the Ru particles are distributed on the surface of the small-sized supports, a few Ru particles are dispersed on the large-sized support surface, while potassium species are more uniformly distributed on all support surfaces, which is consistent with the results given by XRD. Meanwhile, the size of no less than 100 Ru nanoparticles was counted, and the inset of Figure (2) c demonstrates that the Ru size distribution of the reacted Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalysts was around 1.5~5 nm, and Table 1 demonstrates that the average Ru particle size of the Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalysts was about 2.9 nm. The insect of Figure (2) d demonstrates the Ru nanoparticle size statistics, the size distribution of Ru nanoparticles was around 1~4.5 nm, and Table 1 also demonstrated that the average size of Ru/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst was 2.8 nm. Considering the limitation of the electron microscopy results, the average Ru nanoparticle size and dispersion of catalysts were calculated by the method of CO-chemisorption here. According to the results in Table 1, the Ru nanoparticle size of the Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst was about 4.2 nm and the metal dispersion was about 26.7%. The Ru nanoparticle size of the Ru/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst was about 4.3 nm and the metal dispersion was about 23.2%. the CO-chemisorption results imply that the two catalysts are close to each other in terms of Ru size and dispersion. In addition, the XRD spectra (Figure 1) did not show obvious diffraction peaks attributed to Ru, indicating the high dispersion of metal Ru on the catalyst surface since the catalysts had been sufficiently reduced in an NH\u003csub\u003e3\u003c/sub\u003e atmosphere at 500 ゜C prior to test.\u003c/p\u003e\n\u003cp\u003eTable 1 Properties of Ru/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e and Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e(c) catalysts.\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"561\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 12.4555%;\"\u003e\n \u003cp\u003eSample\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 9.96441%;\"\u003e\n \u003cp\u003eSurface area (m\u003csup\u003e2\u003c/sup\u003e g\u003csup\u003e-\u003c/sup\u003e\u003csup\u003e1\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14.5907%;\"\u003e\n \u003cp\u003eLoading of Ru (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14.5907%;\"\u003e\n \u003cp\u003eContents of K (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14.5907%;\"\u003e\n \u003cp\u003eRu particle size by TEM (nm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16.9039%;\"\u003e\n \u003cp\u003eMetal dispersion by CO chemisorption (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16.9039%;\"\u003e\n \u003cp\u003eRu particle size by CO chemisorption (nm)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 12.4555%;\"\u003e\n \u003cp\u003eRu/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 9.96441%;\"\u003e\n \u003cp\u003e52.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14.5907%;\"\u003e\n \u003cp\u003e2.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14.5907%;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14.5907%;\"\u003e\n \u003cp\u003e~2.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16.9039%;\"\u003e\n \u003cp\u003e26.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16.9039%;\"\u003e\n \u003cp\u003e4.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 12.4555%;\"\u003e\n \u003cp\u003eRu/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 9.96441%;\"\u003e\n \u003cp\u003e49.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14.5907%;\"\u003e\n \u003cp\u003e2.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14.5907%;\"\u003e\n \u003cp\u003e3.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14.5907%;\"\u003e\n \u003cp\u003e~2.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16.9039%;\"\u003e\n \u003cp\u003e23.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16.9039%;\"\u003e\n \u003cp\u003e4.3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eCatalytic performances of Ru catalysts\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFigure 3(a) demonstrates the variation of ammonia decomposition reactivity of 5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, Ru/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e and Ru/10% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalysts as a function of temperature, and the 5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e support has no ammonia decomposition reactivity under 450 \u0026deg;C with a GHSV of 30,000 mL g\u003csub\u003ecat\u003c/sub\u003e\u003csup\u003e-1\u003c/sup\u003e h\u003csup\u003e-1\u003c/sup\u003e, while the ammonia conversion of the Ru/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e and Ru/10% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalysts are 61.56%, 93.96% and 90.5%, and the hydrogen production rates are 20.56%, 93.96% and 90.5%, respectively. The hydrogen production rate of the Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst was 1.5 times higher than that of the Ru/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst, which was equal to that of K-5% Ru/CNTs [8] in the literature, and 3.35, 3.58, and 1.23 times than that of 5% Ru/MgO [19], 5% Ru/AC [35], and 5% Ru/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e [32] reported in the literature (seen in Table S2), implying the excellent ammonia decomposition reaction activity of the Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst. In addition, the stability of the catalyst is also critical in influencing the reaction performance. According to the results of Figure 3(b) the catalyst activity did not show any obvious change during the 120 h stability test, and the hydrogen production rate was stably maintained at 31.49 mmol g\u003csub\u003ecat\u003c/sub\u003e\u003csup\u003e-1\u003c/sup\u003e min\u003csup\u003e-1\u003c/sup\u003e, which also confirmed the excellent stability of the Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst. Here, the effect of GHSV on the activity was also analyzed, and it can be seen from Figure S2 that when the GHSV was increased from 8000 to 60,000 mL g\u003csub\u003ecat\u003c/sub\u003e\u003csup\u003e-1\u003c/sup\u003e h\u003csup\u003e-1\u003c/sup\u003e, the hydrogen production rates at different temperatures increased. Under 500 ℃ with a GHSV of 60,000 mL g\u003csub\u003ecat\u003c/sub\u003e\u003csup\u003e-1\u003c/sup\u003e h\u003csup\u003e-1\u003c/sup\u003e, the ammonia conversion of the Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst was still up to 94.64%, and the hydrogen production rate was up to 63.38 mmol g\u003csub\u003ecat\u003c/sub\u003e\u003csup\u003e-1\u003c/sup\u003e min\u003csup\u003e-1\u003c/sup\u003e, which showed excellent performance of hydrogen production from ammonia decomposition.\u003c/p\u003e\n\u003cp\u003eApparent activation energy is a key parameter reflecting the kinetic information of catalysts, and the activation energy of ammonia decomposition reaction is strongly dependent on the structural composition of the supports, the interactions between metal and supports, and the status of the Ru metal, therefore, the data of ammonia conversion in the range of about 10% to 30% are selected here, and the apparent activation energies of the Ru/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, and Ru/10% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalysts were calculated, respectively. Combined with Figure 3(c), the apparent activation energies of Ru/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, and Ru/10% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalysts were 87.5, 73.9, and 71.1 kJ mol\u003csup\u003e-1\u003c/sup\u003e, respectively.Compared with the Ru/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalysts, the apparent activation energies of Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e were significantly lower, which may imply that the enhancement of the basicity of the support had a strong influence on the Ru nanoparticles\u0026apos; properties. In addition, no significant decrease in the activation energy was observed with the increase of potassium species content. Moreover, the apparent activation energies of Ru/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e [32], Ru/MgO [36], Ru/CNTs [36], Ru/AC [36], and Ru clusters/CeO\u003csub\u003e2\u003c/sub\u003e [37] catalysts in the literature were to be 90.4, 102.8, 86.5, 158.0, and 150.0 kJ mol\u003csup\u003e-1\u003c/sup\u003e, respectively, which were higher than those of Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, which may imply the efficient ammonia decomposition performance of the Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst.Turnover of frequency is also an important parameter that can influence the intrinsic activity of the catalysts, and combined with the results of the metal dispersion of CO chemisorption, the TOF value of the Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst can be obtained. From Figure 3(d), it can be found that the TOF value of the Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst is about 6.5 s\u003csup\u003e-1\u003c/sup\u003e, and the intrinsic activity is much higher than that of the catalysts reported in the literature, such as 4.6% K-Ru-MgO [12] and 2.5% Ru/CNTs [12], which further demonstrated that the ultra-high intrinsic activity of the Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStudies on the Reduction Properties of Ru Catalyst\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTo reveal the effect of support basicity on the reduction ability of the catalyst, the H\u003csub\u003e2\u003c/sub\u003e-TPR technique was used to probe the differences in the interactions between metal and supports. Figure 4(a) shows that Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, a weakly reducible oxide, starts to be reduced at a temperature of about 600 \u0026deg;C, and the hydrogen consumption of the support is about 0.05 mmol g\u003csub\u003ecat\u003c/sub\u003e\u003csup\u003e-1\u003c/sup\u003e (Table S3) based on the integral fitting of the peak area, whereas the Ru/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst starts to be reduced at about 200 \u0026deg;C, and is fully reduced at about 500 \u0026deg;C, which corresponds to a hydrogen consumption of about 1.78 mmol g\u003csub\u003ecat\u003c/sub\u003e\u003csup\u003e-1\u003c/sup\u003e (Table S3). The theoretical hydrogen consumption of the pure RuO\u003csub\u003e2\u003c/sub\u003e (RuO\u003csub\u003e3\u003c/sub\u003e) species is about 0.59 (0.89) mmol g\u003csub\u003ecat\u003c/sub\u003e\u003csup\u003e-1\u003c/sup\u003e, and the total hydrogen consumption of the ruthenium and yttrium oxides is still much lower than the actual hydrogen consumption of the catalysts. The change in reduction ability implies that the presence of Ru nanoparticles promotes the reduction of the surface supports and the presence of many overflow hydrogen species on the surface of the supports [38-41]. In contrast, for the Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst, the reduction of Ru nanoparticles occurred before 213 \u0026deg;C with a hydrogen consumption of about 0.3 mmol g\u003csub\u003ecat\u003c/sub\u003e\u003csup\u003e-1\u003c/sup\u003e (Table S3), which is a decrease in the reduction temperature of the RuO\u003csub\u003ex\u003c/sub\u003e species for the Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst as compared to the Ru/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst. The reduction peak between 213 \u0026deg;C and 472 \u0026deg;C implies the reduction of Ru nanoparticles and surface supports with a hydrogen consumption of about 1.24 mmol g\u003csub\u003ecat\u003c/sub\u003e\u003csup\u003e-1\u003c/sup\u003e (Table S3), and the reduction peak after 472 \u0026deg;C implies the reduction of the supports and the presence of spillover hydrogen species, which occupies a hydrogen consumption of about 0.64 mmol g\u003csub\u003ecat\u003c/sub\u003e\u003csup\u003e-1\u003c/sup\u003e (Table S3).The H\u003csub\u003e2\u003c/sub\u003e-TPR results demonstrate that the presence of potassium species promotes the reduction of Ru nanoparticles and supports.\u003c/p\u003e\n\u003cp\u003eThe XPS technique was used to probe the state of Ru species on the catalyst surface, combining with the previous report [42] that the peaks near 284.8 eV should be attributed to the overlapping signals of the Ru 3d\u003csub\u003e3/2\u003c/sub\u003e and C 1s shell layers, and the peaks near 280.4 eV should be attributed to the signals from the Ru 3d\u003csub\u003e5/2\u003c/sub\u003e shell layer. By comparing the signal peaks at the Ru 3d\u003csub\u003e5/2\u003c/sub\u003e position in Figure 4(b), it can be found that there is a difference in the Ru species valence states of the two catalyst, and the peaks centered around 281.7 eV may be attributed to the Ru\u003csup\u003en+\u003c/sup\u003e species [43, 44], and the peaks centered around 280.4 eV may correspond to the Ru\u003csup\u003e0\u003c/sup\u003e species [43, 45, 46]. The content of metallic Ru in both catalysts can be obtained by integrating the peak areas at different positions. For the Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, the value of Ru\u003csup\u003e0\u003c/sup\u003e/(Ru\u003csup\u003en+\u003c/sup\u003e+Ru\u003csup\u003e0\u003c/sup\u003e) is 84.1%, which is 2.8 times higher than that of the Ru/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst (30.1%), implying that the presence of potassium species in the catalyst significantly facilitates the reduction of the RuO\u003csub\u003ex\u003c/sub\u003e species, in agreement with the results of H\u003csub\u003e2\u003c/sub\u003e-TPR.\u003c/p\u003e\n\u003cp\u003eIn addition, in combination with the valence electron spectra of O 1s in Figure 4(c), the peaks near 529 eV should belong to the lattice oxygen species (O\u003csub\u003eL\u003c/sub\u003e) signals of the Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e support according to the results reported in the literature [24, 47, 48], whereas the peaks near 531 eV correspond to the signals of the molecular oxygen (O\u003csub\u003ev\u003c/sub\u003e) adsorbed on the oxygen vacancies on the surface of Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, and the peaks near 531~532 eV correspond to the signals of the Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e surface signal of hydroxyl oxygen (-OH). In general, the value of O\u003csub\u003ev\u003c/sub\u003e/(O\u003csub\u003ev\u003c/sub\u003e+O\u003csub\u003eL\u003c/sub\u003e) can semi-quantify the content of oxygen vacancies in catalysts [42, 49], and by fitting the split peaks in Figure 4(c), the oxygen vacancy concentration of Ru/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e and Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalysts were 36.7% and 57.3%, respectively, which confirmed the existence of a high concentration of oxygen vacancies on the surface of Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalysts. In addition to this, the electron paramagnetic resonance (EPR) technique has been used to study the properties of reduced catalysts in Figure 4(d). According to the literature results [50-52] the position of peaks with g values of 2.002~2.004 on the surface of metal oxides corresponds to the presence of oxygen vacancies. Under the same catalyst loading and testing conditions, combined with the analysis and comparison of the catalyst peak intensities and heights, the difference in the concentration of oxygen vacancies on the surface of the two catalysts can be obtained semi-quantitatively, and the height of the peaks of the Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst is 3.1 times higher than that of the Ru/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst, implying an obvious difference in the concentration of the oxygen vacancies inside the two catalysts, which is in line with the results given by the XPS and the H\u003csub\u003e2\u003c/sub\u003e-TPR.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStudy of the adsorption and desorption processes of ammonia decomposition\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePrevious studies [53-55] found that the dissociation of NH\u003csub\u003e3\u003c/sub\u003e and the binding desorption of N species on the surface of Ru nanoparticles may be the rate-determining step for the ammonia decomposition reaction. Therefore, to investigate the adsorption and desorption rules of the ammonia decomposition process on the surface of the Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalysts, the NH\u003csub\u003e3\u003c/sub\u003e-TPD technique was utilized to reveal the activation ability of the reactant molecules and the product molecules over Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalysts. \u003c/p\u003e\n\u003cp\u003eFigure 5(a) illustrates that the onset temperature of nitrogen desorption over the Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst was around 400 \u0026deg;C, while that of the Ru/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3 \u003c/sub\u003ecatalyst was around 750 \u0026deg;C, implying that the reactive nitrogen species were more easily bound and desorbed on the surface of the Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst, which may be related to the stronger basicity of the Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst [23, 28, 34, 56]. In addition, Figure 5(b) also demonstrates the H\u003csub\u003e2\u003c/sub\u003e desorption signals on the surface of Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e and Ru/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalysts, and both of catalysts have similar onset dehydrogenation temperatures around 700 \u0026deg;C, the Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalysts have stronger H\u003csub\u003e2\u003c/sub\u003e desorption signals, which implies that the surface of the Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalysts has more active hydrogen species. Further, according to Figure 5(c) the Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst showed a weak NH\u003csub\u003e3\u003c/sub\u003e desorption signal near 800 \u0026deg;C, whereas the Ru/Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst showed a stronger NH\u003csub\u003e3\u003c/sub\u003e desorption signal near 800 \u0026deg;C, implying a difference in the adsorption strength of NH\u003csub\u003e3\u003c/sub\u003e on the surface of the two catalysts. The NH\u003csub\u003e3\u003c/sub\u003e-TPD results demonstrated that the Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3 \u003c/sub\u003ecatalyst supported a strong ammonia dissociation and nitrogen binding desorption ability.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eIn conclusion, in this paper, Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalysts with abundant basic sites were successfully prepared by the precipitation deposition method, which demonstrated a hydrogen production rate of 31.49 mmol g\u003csub\u003ecat\u003c/sub\u003e\u003csup\u003e\u0026minus;1\u003c/sup\u003e min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e under 450 ℃ with a GHSV of 30,000 mL g\u003csub\u003ecat\u003c/sub\u003e\u003csup\u003e\u0026minus;1\u003c/sup\u003e h\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, and remained stable over a long period of 120 h test. The relationship between support basicity and the reduction ability of Ru catalysts is demonstrated by TEM, H\u003csub\u003e2\u003c/sub\u003e-TPR, XPS and CO\u003csub\u003e2\u003c/sub\u003e-TPD characterization methods, and the presence of K species in the support promotes the reduction of Ru nanoparticles and the Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, which promotes the formation of many oxygen vacancies. In addition, the NH\u003csub\u003e3\u003c/sub\u003e-TPD results confirmed the strong NH\u003csub\u003e3\u003c/sub\u003e dissociation and N\u003csub\u003e2\u003c/sub\u003e binding desorption ability of the Ru/5% K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst. The findings of this study may provide certain references for the design of efficient Ru-based ammonia decomposition catalysts and broaden the way for the application of the basic supports in heterogeneous catalytic reactions.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe acknowledge the financial support from the National Key Research and Development Program of China (2024YFB3815301), the Natural Science Foundation of China (22179128), and the Major Science and Technology Project of Liaoning Province (2024JH1/11700016).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eJi Feng wrote the main manuscript text, Ningbo Wan help to complete the XRD, TEM, XPS and so on characterization results, all of authors reviewed the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by the National Key Research and Development Program of China (2024YFB3815301), the Natural Science Foundation of China (22179128), and the Major Science and Technology Project of Liaoning Province (2024JH1/11700016).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo datasets were generated or analyzed during the current study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of Interest\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics and Consent to Participate\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for Publication\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eA. 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Dolan, Ammonia decomposition kinetics over LiOH-promoted, \u0026alpha;-Al2O3-supported Ru catalyst, International Journal of Hydrogen Energy, 44 (2019) 3726-3736.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"ammonia decomposition, Ru nanoparticles, basicity, oxygen vacancies, electronic density","lastPublishedDoi":"10.21203/rs.3.rs-7200571/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7200571/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eHydrogen production from ammonia decomposition is a key green hydrogen preparation technology, and the supported ruthenium (Ru) catalyst is one of the most optimally active ammonia decomposition catalysts nowadays, and the basicity of the support has a significant effect on the performance of ruthenium catalysts. In this paper, a potassium-modified yyttrium support (K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e)-supported Ru nanoparticle catalyst was successfully prepared by the precipitation deposition method, and the hydrogen production rate of the 3% Ru/K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalyst was up to 31.49 mmol g\u003csub\u003ecat\u003c/sub\u003e\u003csup\u003e\u0026minus;1\u003c/sup\u003e min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e under 450\u0026deg;C with a gas hour space velosity of 30,000 mL g\u003csub\u003ecat\u003c/sub\u003e\u003csup\u003e\u0026minus;1\u003c/sup\u003e h\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, which was an order of magnitude higher than that of K-4.6% Ru/MgO catalyst. Moreover, the catalyst activity did not decay significantly during a 120 h test. Combined with TEM, NH\u003csub\u003e3\u003c/sub\u003e-TPD, XPS, CO\u003csub\u003e2\u003c/sub\u003e-TPD and other characterization methods, it was found that the presence of K species enhanced the basicity of the support, promoted the reduction of Ru nanoparticles and surface Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e supports, and increased the electron density of Ru nanoparticles and the oxygen vacancy concentration of the support, thus the Ru/K-Y\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e catalysts had strong ammonia dissociation and nitrogen-binding desorption ability to enhance its performance in ammonia decomposition reaction.\u003c/p\u003e","manuscriptTitle":"Basicity Modification of the Yttrium oxide supported ruthenium nanoparticles catalysts to enhance catalytic performance for hydrogen production from ammonia decomposition","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-08-18 13:47:58","doi":"10.21203/rs.3.rs-7200571/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"d9cfbd6f-4378-4830-88d4-a3a300cb1bdc","owner":[],"postedDate":"August 18th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-01-05T10:39:06+00:00","versionOfRecord":[],"versionCreatedAt":"2025-08-18 13:47:58","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7200571","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7200571","identity":"rs-7200571","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}