One-step Synthesis of highly ordered mesoporous Fe/carbon composites using soft templating routes

One-step Synthesis of highly ordered mesoporous Fe/carbon composites using soft templating routes | 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 One-step Synthesis of highly ordered mesoporous Fe/carbon composites using soft templating routes Jiang-Tao Li, Jing Li, Xue-Kun Li, Li-Mei Song, Liu-Chang Wang, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7392990/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 Ordered mesoporous PFR-Fe/C composites have been synthesized via a ‘‘one-pot’’ assembly strategy associated with a direct carbonization process by using phenolic resol (PR) as a carbon source, inorganic salt hydrated iron nitrite as an iron source and amphiphilic triblock copolymer Pluronic F127 as a template. The main strategy of this approach is to use the iron precursors as the coordinationcenter with phenol. The obtained mesoporous Fe/Fe 2 O 3 /carbon composites (PFR/C-Fe) exhibit uniform pore sizes about 6.78 nm, high specific surface areas about 572 m 2 g -1 , and high pore volumes 0.70 cm 3 g -1 . With this facile ‘‘one-pot’’ assembly approach, one can incorporate as high as about 30 wt % of iron in the composites. The resultant materials were characterized using nitrogen sorption, X-ray diffraction, and transmission electron microscopy. It was found that the final products with a highly ordered mesostructure were obtained when the Fe/R ratio was around 1:6. Especially, the increased iron content induces the enlarged particle sizes of the iron nanocrystals, together with a high dispersion in the amorphous carbon framework, but the ordering decreased. Iron species in the mesoporous carbon matrix existed in two states, metallic Fe and α-Fe 2 O 3 . Metallic Fe nanoparticles are dominantly buried in the walls of the mesoporous carbon while α-Fe 2 O 3 nanoparticles are mostly located on the surface. When the iron particles have sizes larger than the mesopore wall thickness, they can extend from the carbon walls into mesopore channels, and hence bring a rougher pore surface and a lower degree of mesostructure regularity. These mesoporous Fe/Fe 2 O 3 /carbon composites materials composites with high surface area, large pore size and super paramagnetic property show excellent adsorption properties for bulky dye fuchsin base. The excellent magnetic materials makes it useful in magnetic separation. Iron Mesoporous carbon Synthesis Soft templating Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 1. Introduction Ordered mesoporous carbon (OMC) materials are of great interests for various applications, such as separation, catalyst supports, adsorption, energy storage/conversion, and biomedical engineering. [ 1 – 5 ] Till now, there has been increasing research attention to the fabrication of OMC with uniform pore architecture, high surface area, electrical conductivity, thermal stability, chemical inertness, biocompatibility, and specific surface properties. [ 6 – 12 ] These features contribute to the high performances of these materials in various applications. Particularly, a recent development in this field is directed to the porous nanocrystalline/carbon composites in which ‘‘foreign’’ nanocrystalline materials are assembled into the matrix of mesoporous carbons. Compared with single phase mesoporous carbon materials, the mesoporous nanocrystalline/carbon composites own greatly extended applications. [ 13 , 14 ] Two research groups have reported that mesoporous carbons with suitable modifications can generate large amount of acidic sites on their mesopore surfaces. [ 15 , 16 ] For further applications of OMC, it would be interesting to employ metal nanoparticles into mesoporous carbon matrix to modify its properties. Conventional incorporation techniques can be summarized in two routes. One route is incorporating metal nanoparticles into the pre-synthesized OMC materials using impregnation, adsorption or ion exchange methods. Another route is called co-casting, which involves two main steps: (1) preparation of a mesostructured silica template and (2) filling the silica mesopore with an appropriate carbon precursor and metal source, followed by carbonization and removal of silica framework with NaOH or HF. Nevertheless, these two routes seem to be fussy, time-consuming and low effective to disperse metals throughout the carbon matrix. It is therefore desirable to incorporate active metal species into mesoporous carbon during synthesis of OMC through soft templating routes, while retaining the ordered mesostructure. Recently, incorporation of Fe, [ 17 ] TiO 2 , [ 18 ] Ir, [ 19 ] and Ru [ 20 ] nanoparticles into mesoporous carbons, has been accomplished by soft templating routes. Owning to excellent magnetic property and extreme reactivity, iron nanoparticles are more preferred candidates for many advanced nanotechnological applications, such as magnetic storage media, [ 21 ] directed drug delivery, [ 22 ] Fischer–Tropsch synthesis, [ 23 ] and groundwater remediation or other environmental applications. [ 24 ] There had been some reports on the Fe/OMC prepared by hard templating method. [ 25 , 26 ] However, to our best knowledge, there is no report on the synthesis of PFR-Fe/C via “chelate” routes can be found in current literatures. Herein, we have developed a simple method for facile synthesis of PFR-Fe/C composites under a moderate acidic condition. In this method, phenolic resol was used as a carbon precursor, triblock copolymer Pluronic F127 was used as a template agent and hydrated iron nitrite as an iron source. Our strategy is that the phenolic as a complexant and the hydrated iron nitrite as a coordinationcenter synthetized “chelate”. Furthermore, after the hydrated iron nitrite chelated with phenolic, and further polymer with formaldehyde. Simultaneously, Fe species are introduced to the ordered mesostructure and subsequently reduced to Fe 0 during the carbonization process at high temperature under inert atmosphere. To obtain a well-ordered structure, an important factor: the effects of iron loading contents was considered. 2. Experimental 2.1. Chemicals Triblock poly(ethylene oxide)-b-poly(propylene oxide)-bpoly(ethylene oxide) copolymer Pluronic F127 (MW = 12600, PEO 106 PPO 70 PEO 106 ) was purchased from Aldrich Corp., and phenolic, formaldehyde and hydrated iron nitrite [Fe(NO 3 ) 3 · 9H 2 O] were purchased from Shanghai Chemical Corp. All chemicals were analytical pure grade and were used as received without any further purification. 2.2. Synthesis Mesoporous PFR-Fe/C composites materials were synthesized by using triblock copolymer as a template, phenol/formaldehyde as a carbon precursor and inorganic salt hydrated iron nitrite as an iron source. Firstly, 2.0 g (21 mmol) of phenol and 7.0 ml of formaldehyde solution (40 wt%, 100 mmol) were dissolved in 50 ml (5 mmol) of 0.1 M NaOH solution. Then the mixture was stirred at 70°C for 30 min. A clear precursor solution (about 60 ml) was obtained, denoted as Solution-P. For a typical synthesis of mesoporous carbon, 5.6 g of F127 (~ 0.44mmol) was dissolved in 50 ml of water. Then 60 ml of Solution-P was added into the above solution, and a clear solution was obtained. The solution turned dark red as stirred at 66°C for about 3 h with a rate of ~ 300rpm. Subsequently, 2g the hydrated iron nitrite [Fe (NO 3 ) 3 ·9H 2 O] was added into the above solution. The solution turned from dark red to dark blue. Dark blue precipitation was observed after about 48 h. The mixture was continuously stirred at 66°C for additional 72 h and then stirred at 70°C for another 24 h. The final product was collected by sedimentation separation and filtration, washed with water and dried in air. The obtained sample was calcined at 700°C for 3 h in nitrogen flow to obtain mesoporous Fe/Fe 2 O 3 /carbon composites materials. The heating rate was fixed at 1°C/min. 2.3. Characterization Powder X-ray diffraction (XRD) patterns were recorded on a Rigaku D/max-r system operating with Cu Ka (k = 1.5406) radiation. High-resolution transmission electron microscopy (HRTEM) images were obtained using a JEOL JEM-2100 microscope, operating at 200 kV. For TEM measurements, the samples were prepared by dispersing the powdered products as slurry in ethanol with a ultrasonic bath for about 10 min, and then one drop of the resulting suspension was dispersed and dried on a holey carbon film on a copper grid. N 2 adsorption–desorption isotherms were measured using Micromeritics ASAP-2010 at liquid nitrogen temperature (77 K). Prior to measurements, all samples were degassed at 473 K for 12 h. The specific surface areas were evaluated using the Brunauer-Emmett-Teller (BET) method. The pore size distribution was derived from the desorption branches of the isotherms using the Barrett-Joyner-Halenda (BJH) method. 2.4. Adsorption experiments for dyes Adsorption behaviors of synthesized ordered mesoporous Fe/carbon composites to dyestuff was evaluated by the qualitative filtration of fuchsin base and the adsorption isotherms for the dye-adsorbent systems. The adsorption isotherms were measured as follows. An adsorbent (Blank, active carbon (AC), PFR-Fe/C-0.10) of 5 mg was dispersed in an aqueous solution (10 mL) of the fuchsin base in guest concentration(1 g L − 1 ). The dispersion mixtures were shaken vigorously (160 rpm) for 24 h under precise temperature control (35℃). The adsorbents were filtered, and guest concentrations in solution at equilibrium were ascertained using UV–vis spectroscopy at 553 nm for fuchsin base. The adsorption experiments were conducted at various initial concentrations of the guests, and the equilibrium guest concentrations obtained and adsorbed amounts of the guests were plotted as adsorption isotherms. 3. Results and discussion The synthesis strategy for mesostructured magnetic PFR-Fe/C composites is presented in Fig. 1. In step 1, appropriate amounts of F127 were introduced into the aquation to form micelles; networks were formed in F127 system via the addition of highly cross-linked polymeric PR/[Fe(NO 3 ) 3 ·9H 2 O], stirring aquation at room temperature for 24 h, form PR/F127/ [Fe(NO 3 ) 3 ·9H 2 O]; In step 2, the composite was carbonized under N 2 at 700°C, and Fe 3+ of [Fe(NO 3 ) 3 ·9H 2 O] was reduced to metallic iron. Moreover, the carbon served as a block to confine the growth of iron nanoparticles during carbonization. It reveals that metallic nanoparticle in the mesoporous carbon matrix existed in two types: surface and in wall (fig.1). In fig.1, (a) Schematic representation of Fe(NO 3 ) 3 · 9H 2 O)/PR structure. (b) Schematic model for the PFR-Fe/C structure. The low-angle XRD patterns of PFR-Fe/C composites with Fe/R molar ratios are presented in Fig. 2. The PFR/C-Fe-0.05 (Fig. 2a) and PFR-Fe/C-0.10 (Fig. 2b) samples show an intense diffraction peak at 2θ range of 0.5-1°, which can be indexed to [100] reflection of a hexagonal mesostructure. [19] In particular, a sharp and narrow diffraction peak at 2θ= 0.70° can be observed for PFR-Fe/C-0.10, which indicates that this sample possesses well-ordered mesostructure. However, just a discernible weak peak at 2θ = 0.68° was observed in the PFR-Fe/C-0.20 samples (Fig. 2c), implying that the optimal ordering of the hexagonal mesostructure can be obtained when Fe contents around Fe/R=0.1 and the ordering decreased as the Fe content was either greater or smaller than this ratio. Clearly, a suitable amount of Fe present in the synthesis system would lead to a highly ordered mesostructure. This phenomenon can be explained from the preparing process of the PFR-Fe/C samples. In this synthesis, when iron precursor was added into the reaction mixture containing resol and F127. And it can be used as the catalyst for cross-linking between P and F, simultaneously, P and Fe 3+ happen “chelate”. However, the presence of excess iron species might destroy the final ordering of the mesostructure，as the carbonization process occur redox reaction. The wide-angle XRD patterns (Fig. 3) exhibit a resolved diffraction peaks at 2θ= 43.5° and a intense diffraction peak at 35.4° for PFR-Fe/C-0.10, which are in accordance with the (110) diffraction of body-centered cubic (bcc) α-Fe (JCPDS card No. 06-0696) and the (311) diffraction of γ-Fe 2 O 3 (JCPDS card No. 00-039-1346), respectively. It reveals that the iron species in the mesoporous carbon matrix exists in two states: metallic Fe and γ-Fe 2 O 3 . According to Hoch et al., [27] iron nanoparticles (20-100 nm diameter) supported on carbon (C–Fe 0 ) can be synthesized by carbothermal reduction of iron salts and carbon black under inert atmosphere, and the threshold temperature is 600°C. Here, PFR-Fe/C was synthesized through carbonization process at the temperature as high as 700°C. Therefore, it can be believed that all Fe species can be reduced to Fe nanoparticles. In this study, the existence of γ-Fe 2 O 3 may be due to the fact that metallic Fe possesses extremely high reactivity and thus can be easily oxidized to iron oxides when exposed in the air. [21] Furthermore, when the ratio of Fe/R is beyond 0.10, an intensive diffraction peak at 2θ= 26°, along with 3 resolved diffraction peaks at 2θ= 43°, 54°, and 78° can be observed in the resulting PFR-Fe/C composites, which can be indexed to the (002), (101), (004), and (110) diffraction peak for typical graphite-like carbon, respectively. [28] The results indicate that the prepared materials are graphitized during carbonization at 700 °C which is much lower than graphitized temperature of pure OMC. [29] The lower graphitized temperature of PFR-Fe/C is due to the existence of the iron nanoparticles. It is well known that the nanosized metals such as Fe, Co, Ni, Mo can accelerate the development of graphitic structure of carbon when they are heat-treated together in inert gas atmosphere. [30] The mesostructures of the PFR-Fe/C-0.10 sample and the distribution of iron species in the final materials are investigated with TEM. As shown in Fig. 4, iron species distributed uniformly in resol before calcine (Fig. 4A), parallel channels with a d spacing of about 10 nm are clearly observed on PFR-Fe/C-0.10, which is consistent with the XRD results, and an orderly arranged strip-like channels structure can also be observed (Fig. 4B). The finger-like column-shaped structure can also be observed from edges of strip-like channels structure, although the regularity is not very good, indicating that iron species were introduced in PR polymerization. (Fig. 4C), In order to further understand the existing state of iron species in OMC, detailed HRTEM analysis was performed (Fig. 4D). We have randomly observed many particles which were embedded in OMC or exposed on its surface. It can also be found that the nanoparticles, the dark spots, were dominantly dispersed on the walls of the OMC, They are iron as a d spacing of about 2-3 Å are clearly observed. For the samples with lower Fe contents, the particle size is smaller. When the Fe/R molar ratio increased to 0.10 or more, bigger particles with the diameter of 20-30 nm were obtained owning to aggregation of small nanoparticles. Nevertheless, the size of these incorporated nanoparticles is much smaller than that of support-free nanoparticles. [31] Therefore, we conclude that OMC materials not only stabilize the Fe nanoparticles by avoiding their aggregation to some extent, but also confine the growth of nanoparticles. Furthermore, as shown in these images, the ordered structures of PFR-Fe/C composites with highly dispersed nanoparticles can be maintained Fe/R molar ratio up to 0.10. These HRTEM images illustrate the perfect arrangements of the atomic layers and lack of defects. The lattice plane distance in Fig. 4D is 2.03Å, which is consistent with the [110] plane of the α-Fe (JCPDS card No. 06-0696). From the above analysis, it reveals that iron species in the mesoporous carbon matrix existed in two states: metallic Fe and γ-Fe 2 O 3 . In principle, when carbonaceous materials containing metallic salts were heat-treated under inert atmosphere, PF polymers were carbonized and meanwhile the metallic salts first decomposed to metallic oxides. With the increasing temperature, metallic oxides were gradually reduced to metallic elements by carbonaceous materials. As reported by Chen et al., iron oxides existed in the bores of carbon nanotubes or on its outer surface can be reduced to metallic Fe when heat-treated temperature reached 800°C. [33] Owing to the fact that metallic Fe particles are extremely active and prone to be oxidized by air at room temperature, Fe species located on the surface of OMC mostly exist as γ-Fe 2 O 3 particles while Fe species buried in the walls of OMC dominantly present as metallic Fe particles. The γ-Fe 2 O 3 particles supported on the surface of OMC together with the carbon matrix, probably can protect the bcc-Fe particles embedded in the walls of OMC from oxidation. Fig. 5 shows N 2 sorption isotherms and pore size distribution of the PFR-Fe/C-0.10 composite. It exhibits typical type IV isotherms with an obvious H3-type hysteresis loop, indicating the mesoporous structures of the materials. The sharp inflections between the relative pressures p/p 0 =0.4-0.8 in these isotherms correspond to capillary condensation within uniform mesopores. The pore size distributions are very narrow, centering at around 6.78 nm for PFR-Fe/C-0.10 composite. PFR-Fe/C-0.10 has a surface area of 572 m 2 /g and pore volume of 0.70cm 3 /g. These N 2 adsorption-desorption data are in well agreement with the Low-angle XRD (Fig. 2) and TEM (Fig. 4) results. Obviously, the moderate amount iron precursor is favorable to the formation of a well-ordered mesoporous structure. We want to know whether it possesses high adsorbility for fuchsin base. Many industries use dyes to color their products and discharge their waste in water which directly pollute the soil, water, plants and all living systems in the environment. Fuchsin base is an organic dyes used in high frequency. Thereby, we investigated the adsorbility of PFR-Fe/C-0.10 to fuchsin base in water as seen in Fig. 5. An adsorbent (Blank, AC, PFR-Fe/C-0.10) of 5 mg was dispersed in an aqueous solution (10 mL) of the fuchsin base in guest concentration(1 g L -1 ). The dispersion mixtures were shaken vigorously (160 rpm) for 24 h under precise temperature control (35℃). The result indicated PFR-Fe/C-0.10 completely removed fuchsin base from water, while the AC tested materials were not very effective for removal of the dyes. It is clearly observed that the volume of solution decolored by PFR-Fe/C-0.10) is bigger than AC tested materials. Adsorption processes have attained great importance as an environmental point of view that they can remove toxic compounds and easy separation procedure from industrial waste water. The results have shown that PFR-Fe/C-0.10 material has a high adsorption capacity for fuchsin base and this material may be found useful as a sorbent in waste water treatments. 4. Conclusions Highly ordered Fe-containing mesostructure carbon materials can be directly prepared using soft templating routes without the addition of mineral acids. The acidity self-generated by the iron precursor should be enough to catalyze the polymerization of PF. The optimal ordering mesostructure can be obtained when the Fe/R molar ration is around 0.1. The iron species are spontaneously reduced to metallic iron by carbonaceous materials during carbonization. Fe species located on the surface of OMC mostly present as γ-Fe 2 O 3 particles while Fe species buried in the walls of OMC dominantly as metallic Fe particles due to extreme reactivity of metallic iron. The resulting materials possess specific activity for catalytic wet peroxide oxidation of phenol in solution. It is believed that the easy soft templating synthesis approach reported here can be readily expanded its scope to synthesize other metals containing OMC materials. Moreover, such highly ordered mesoporous PFR-Fe/C composites may be applied in the fields of separation, catalysis, and environment remediation. Declarations Author Contribution J.T.L. and J.L. wrote the main manuscript text and X.K.L., L.M.S prepared figures 1, G.Z., L.C.W and P.N.L prepared figures 2-7. All authors reviewed the manuscript. Acknowledgments The work is supported by Xi'an Science and Technology Program (No. 23GXFW0081-04), the National Science Foundation of China (21541009), (21706209), the Industrial research project of Science and Technology Department of Shaanxi Province (No. 2013K09-25) and Education Department of Shaanxi provincial Government Project Foundation (2013JK0665), and the Science & Technology Project Foundation Xi’an (No. 2017GY-126). References T. Yu, Y. H. Deng, L. Wang, R. L. Liu, L. J. Zhang, B. Tu and D. Y. Zhao, Adv. Mater., 2007, 19, 2301. A. H. Lu, W. Schmidt, N. Matoussevitch, H. Bonnemann, B. Spliethoff, B. Tesche, E. Bill, W. Kiefer and F. Sch€uth, Angew. Chem., Int. Ed., 2004, 43, 4303. J. Lee, S. M. Jin, Y. Hwang, J. G. Park, H. M. Park and T. Hyeon, Carbon, 2005, 43, 2536. P. Gao, A. Q. Wang, X. D. Wang and T. Zhang, Chem. Mater., 2008, 20, 1881. C. D. Liang, Z. J. Li and S. Dai, Angew. Chem., Int. Ed., 2008, 47, 3696. Y. Wan, Y. F. Shi and D. Y. Zhao, Chem. Mater., 2008, 20, 932. R. Ryoo, S. H. Joo and S. Jun, J. Phys. Chem. B, 1999, 103, 7743. C. D. Liang, K. L. Hong, G. A. Guiochon, J. W. Mays and S. Dai, Angew. Chem., Int. Ed., 2004, 43, 5785. S. Tanaka, N. Nishiyama, Y. Egashira and K. Ueyama, Chem. Commun., 2005, (16), 2125. Y. Meng, D. Gu, F. Q. Zhang, Y. F. Shi, H. F. Yang, Z. Li, C. Z. Yu, B. Tu and D. Y. Zhao, Angew. Chem., Int. Ed., 2005, 44, 7053. F. Q. Zhang, Y. Meng, D. Gu, Y. Yan, C. Z. Yu, B. Tu and D. Y. Zhao, J. Am. Chem. Soc., 2005, 127, 13508. Y. Wan, H. F. Yang and D. Y. Zhao, Acc. Chem. Res., 2006, 39, 423. A. H. Lu and F. Sch€uth, Adv. Mater., 2006, 18, 1793. J. Lee, J. Kim and T. Hyeon, Adv. Mater., 2006, 18, 2073. P. A. Bazula, A. H. Lu, J. J. Nitz and F. Sch€uth, Microporous Mesoporous Mater., 2008, 108, 266. D. W. Wang, F. Li, M. Liu and H. M. Cheng, New Carbon Mater., 2007, 22, 307. Jiansheng Li, Juan Gu, Huijun Li, Yi Liang, Yanxia Hao, Xiuyun Sun, Lianjun Wang, Synthesis of highly ordered Fe- containing mesoporous carbon materials using soft templating routes. Microporous and Mesoporous Materials 128 (2010) 144. R. Liu, Y. Ren, Y. Shi, F. Zhang, L. Zhang, B. Tu, D.Y. Zhao, Chem. Mater. 20 (2008) 1140. P. Gao, A. Wang, X. Wang, T. Zhang, Chem. Mater. 20 (2008) 1881. P. Gao, A.W. Wang, X.D. Wang, T. Zhang, Catal. Lett. 125 (2008) 289. D.L. Huber, Small 1 (2005) 482. R. Fernandez-Pacheco, M. Arruebo, C. Marquina, R. Ibarra, J. Arbiol, J. Santamaria, Nanotechnology 17 (2006) 1188. W. Chen, Z.L. Fan, X.L. Pan, X.H. Bao, J. Am. Chem. Soc. 130 (2008) 9414. J.T. Nurmi, P.G. Tratnyek, V. Sarathy, D.R. Baer, J.E. Amonette, K. Pecher, C.M. Wang, J.C. Linehan, D.W. Matson, R.L. Penn, M.D. Driessen, Environ. Sci. Technol. 39 (2005) 1221. X. Yuan, W. Xing, S. Zhuo, Z. Han, G. Wang, X. Gao, Z. Yan, Micropor. Mesopor. Mater. 117 (2009) 678. Z. Gu, B. Deng, J. Yang, Micropor. Mesopor. Mater. 102 (2007) 265. L.B. Hoch, E.J. Mach, B.W. Hydutsky, J.M. Hershman, J.M. Skluzacek, T.E. Mallouk, Environ. Sci. Technol. 42 (2008) 2600. M. Sevilla, A.B. Fuertes, Carbon 44 (2006) 468. X. Wang, C. Liang, S. Dai, Langmuir 24 (2008) 7500. W. Weisweiler, N. Subramanian, B. Terwiesch, Carbon 9 (1971) 755. C.B. Wang, W.X. Zhang, Environ. Sci. Technol. 31 (1997) 2154. R.P. Hodgkins, A. Ahniyaz, K. Parekh, L.M. Belova, L. Bergstrom, Langmuir 23 8838. W. Chen, X.L. Pan, M.G. Willinger, D.S. Su, X.H. Bao, J. Am. Chem. Soc. 128 3136. A. Santos, P. Yustos, A. Quintanilla, S. Rodriguez, F. Garcia-Ochoa, Appl. Catal. B 39 (2002) 97. J. Barrault, M. Abdellaoui, C. Bouchoule, A. Majeste, J.M. Tatibouet, A. Louloudi, N. Papayannakos, N.H. Gangas, Appl. Catal. B 27 (2000) 225. Additional Declarations No competing interests reported. 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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-7392990","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":508162088,"identity":"3e540281-3e6f-493e-a477-68e5623c16ef","order_by":0,"name":"Jiang-Tao Li","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABEklEQVRIie2RsWrDMBBAzzU4FOxqVTF1fsEhY0q/xSLQju0UMqRGk7q0dBUU8g/ZOsoImkW4q8CFJh9QSLZ2CEQCL4UIZ8ygt5y4u8edJACP5wS5CKEQ7TlYbabXJoYUIHIrUatg2zrg6taqHUobrRKl50weofRgLf7eH0v0RKMU1Cd55YTCZiIBvVHnYtWLWmKsRDh6mDZDrAkNeC0BfwmnIhL2gUHfbxuumgwaQsPEbJjjwj1lZ5S+LiBNWB33rbLrUGTCZjjXxZlRRJZbJehSrpi4XJi7mEceDwffa1o913cx1ocVhNR4+8NKlC2p/cobMleyWv1ORhnihxWA2Bbk/5yweUe/oWfrpbvu8Xg8nj0UumPfzfLCsAAAAABJRU5ErkJggg==","orcid":"","institution":"","correspondingAuthor":true,"prefix":"","firstName":"Jiang-Tao","middleName":"","lastName":"Li","suffix":""},{"id":508162090,"identity":"cad67bde-e3fd-4314-a5e9-b05ae302fd85","order_by":1,"name":"Jing Li","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Jing","middleName":"","lastName":"Li","suffix":""},{"id":508162092,"identity":"f89cd30e-28e7-4e1d-aa39-e4a41bff3cf2","order_by":2,"name":"Xue-Kun Li","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Xue-Kun","middleName":"","lastName":"Li","suffix":""},{"id":508162095,"identity":"3586666d-34e6-44e3-b221-d6c67848da18","order_by":3,"name":"Li-Mei Song","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Li-Mei","middleName":"","lastName":"Song","suffix":""},{"id":508162096,"identity":"11c0a455-dd3a-4e7e-a005-0830a5f6ee27","order_by":4,"name":"Liu-Chang Wang","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Liu-Chang","middleName":"","lastName":"Wang","suffix":""},{"id":508162099,"identity":"5b7ffed6-807c-4612-a955-6b8fd5cbad29","order_by":5,"name":"Pen-Na Li，Gang","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Pen-Na","middleName":"","lastName":"Li，Gang","suffix":""},{"id":508162101,"identity":"137056ea-a655-4716-a9f6-f814459f9fd1","order_by":6,"name":"Gang Zhu","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Gang","middleName":"","lastName":"Zhu","suffix":""}],"badges":[],"createdAt":"2025-08-17 14:38:20","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7392990/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7392990/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":90492801,"identity":"d08f5058-d21e-4ed3-9946-01b44162200c","added_by":"auto","created_at":"2025-09-03 09:58:20","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":121016,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic of the PFR-Fe/C preparation. (a) Schematic representation of [Fe(NO3)3· 9H2O]/PR structure. (b) Schematic model for the Fe/OMC structure.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7392990/v1/b05ee72509fcb15988c7cb33.png"},{"id":90493055,"identity":"0acf27b7-e2a2-4c9c-b600-08b896bc4f24","added_by":"auto","created_at":"2025-09-03 10:06:20","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":25352,"visible":true,"origin":"","legend":"\u003cp\u003eLow-angle XRD patterns of PFR-Fe/C composites with different iron loading after carbonization (a) PFR/C-Fe-0.05, (b) PFR/C-Fe-0.10, (c) PFR/C-Fe -0.20.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7392990/v1/3d5df8fb274461dd7d08ad34.png"},{"id":90493058,"identity":"a9811099-c05c-40d7-a992-7152f903ae36","added_by":"auto","created_at":"2025-09-03 10:06:21","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":174789,"visible":true,"origin":"","legend":"\u003cp\u003ePowder XRD patterns with PFR-Fe/C-0.10\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-7392990/v1/964c6840dbda9f3c23f65ed2.png"},{"id":90492804,"identity":"74a42931-c63c-4dc9-9705-71063fbe6feb","added_by":"auto","created_at":"2025-09-03 09:58:20","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":10944,"visible":true,"origin":"","legend":"\u003cp\u003eTEM images of PFR-C/Fe-0.10 (A) Before calcine (B) and (C) After calcined (D)\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7392990/v1/9442674c58d00fb034bf9047.png"},{"id":90493057,"identity":"2d459655-2ce5-47ae-8933-da51321488d4","added_by":"auto","created_at":"2025-09-03 10:06:21","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":33523,"visible":true,"origin":"","legend":"\u003cp\u003eN\u003csub\u003e2\u003c/sub\u003e adsorption/desorption isotherms and pore size\u003c/p\u003e\n\u003cp\u003edistributions (inset) of PFR-C/Fe-0.10\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-7392990/v1/156388348e577765cb25bfae.png"},{"id":90492810,"identity":"a96c3fb2-3d01-4f60-8593-6c8879a0901e","added_by":"auto","created_at":"2025-09-03 09:58:21","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":294987,"visible":true,"origin":"","legend":"\u003cp\u003ePhoto of two phase mixtures after aging for 24 h. The adsorbilities of two adsorbents (a) Blank, (b) AC, (c) PFR-Fe/C-0.10 to bulky dye fuchsin base in water.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-7392990/v1/699b589e2cb818323c38f932.png"},{"id":90492808,"identity":"2fdd53c7-9c21-4ce7-b66d-9dfab94940cd","added_by":"auto","created_at":"2025-09-03 09:58:21","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":142211,"visible":true,"origin":"","legend":"\u003cp\u003eThe PFR-Fe/C-0.10 adsorption properties for fuchsin base and easy separation procedure.\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-7392990/v1/9c02b04548cf834316ccc8ff.png"},{"id":91790656,"identity":"ab020e27-0497-4115-b8ac-293fcb83f5eb","added_by":"auto","created_at":"2025-09-21 11:46:30","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1269482,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7392990/v1/b4d2ed8c-d6c2-4353-9631-4ba56330c561.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"One-step Synthesis of highly ordered mesoporous Fe/carbon composites using soft templating routes","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eOrdered mesoporous carbon (OMC) materials are of great interests for various applications, such as separation, catalyst supports, adsorption, energy storage/conversion, and biomedical engineering.\u003csup\u003e[\u003cspan additionalcitationids=\"CR2 CR3 CR4\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e Till now, there has been increasing research attention to the fabrication of OMC with uniform pore architecture, high surface area, electrical conductivity, thermal stability, chemical inertness, biocompatibility, and specific surface properties.\u003csup\u003e[\u003cspan additionalcitationids=\"CR7 CR8 CR9 CR10 CR11\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]\u003c/sup\u003e These features contribute to the high performances of these materials in various applications. Particularly, a recent development in this field is directed to the porous nanocrystalline/carbon composites in which \u0026lsquo;\u0026lsquo;foreign\u0026rsquo;\u0026rsquo; nanocrystalline materials are assembled into the matrix of mesoporous carbons. Compared with single phase mesoporous carbon materials, the mesoporous nanocrystalline/carbon composites own greatly extended applications.\u003csup\u003e[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]\u003c/sup\u003e Two research groups have reported that mesoporous carbons with suitable modifications can generate large amount of acidic sites on their mesopore surfaces.\u003csup\u003e[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/sup\u003e\u003c/p\u003e\u003cp\u003eFor further applications of OMC, it would be interesting to employ metal nanoparticles into mesoporous carbon matrix to modify its properties. Conventional incorporation techniques can be summarized in two routes. One route is incorporating metal nanoparticles into the pre-synthesized OMC materials using impregnation, adsorption or ion exchange methods. Another route is called co-casting, which involves two main steps: (1) preparation of a mesostructured silica template and (2) filling the silica mesopore with an appropriate carbon precursor and metal source, followed by carbonization and removal of silica framework with NaOH or HF. Nevertheless, these two routes seem to be fussy, time-consuming and low effective to disperse metals throughout the carbon matrix. It is therefore desirable to incorporate active metal species into mesoporous carbon during synthesis of OMC through soft templating routes, while retaining the ordered mesostructure. Recently, incorporation of Fe,\u003csup\u003e[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]\u003c/sup\u003e TiO\u003csub\u003e2\u003c/sub\u003e,\u003csup\u003e[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/sup\u003e Ir,\u003csup\u003e[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]\u003c/sup\u003e and Ru\u003csup\u003e[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]\u003c/sup\u003e nanoparticles into mesoporous carbons, has been accomplished by soft templating routes. Owning to excellent magnetic property and extreme reactivity, iron nanoparticles are more preferred candidates for many advanced nanotechnological applications, such as magnetic storage media, \u003csup\u003e[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]\u003c/sup\u003e directed drug delivery,\u003csup\u003e[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]\u003c/sup\u003e Fischer\u0026ndash;Tropsch synthesis,\u003csup\u003e[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]\u003c/sup\u003e and groundwater remediation or other environmental applications.\u003csup\u003e[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]\u003c/sup\u003e There had been some reports on the Fe/OMC prepared by hard templating method.\u003csup\u003e[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]\u003c/sup\u003e However, to our best knowledge, there is no report on the synthesis of PFR-Fe/C via \u0026ldquo;chelate\u0026rdquo; routes can be found in current literatures.\u003c/p\u003e\u003cp\u003eHerein, we have developed a simple method for facile synthesis of PFR-Fe/C composites under a moderate acidic condition. In this method, phenolic resol was used as a carbon precursor, triblock copolymer Pluronic F127 was used as a template agent and hydrated iron nitrite as an iron source. Our strategy is that the phenolic as a complexant and the hydrated iron nitrite as a coordinationcenter synthetized \u0026ldquo;chelate\u0026rdquo;. Furthermore, after the hydrated iron nitrite chelated with phenolic, and further polymer with formaldehyde. Simultaneously, Fe species are introduced to the ordered mesostructure and subsequently reduced to Fe\u003csup\u003e0\u003c/sup\u003e during the carbonization process at high temperature under inert atmosphere. To obtain a well-ordered structure, an important factor: the effects of iron loading contents was considered.\u003c/p\u003e"},{"header":"2. Experimental","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003e2.1. Chemicals\u003c/h2\u003e\u003cp\u003eTriblock poly(ethylene oxide)-b-poly(propylene oxide)-bpoly(ethylene oxide) copolymer Pluronic F127 (MW\u0026thinsp;=\u0026thinsp;12600, PEO\u003csub\u003e106\u003c/sub\u003ePPO\u003csub\u003e70\u003c/sub\u003ePEO\u003csub\u003e106\u003c/sub\u003e) was purchased from Aldrich Corp., and phenolic, formaldehyde and hydrated iron nitrite [Fe(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e\u0026middot; 9H\u003csub\u003e2\u003c/sub\u003eO] were purchased from Shanghai Chemical Corp. All chemicals were analytical pure grade and were used as received without any further purification.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\u003ch2\u003e2.2. Synthesis\u003c/h2\u003e\u003cp\u003eMesoporous PFR-Fe/C composites materials were synthesized by using triblock copolymer as a template, phenol/formaldehyde as a carbon precursor and inorganic salt hydrated iron nitrite as an iron source. Firstly, 2.0 g (21 mmol) of phenol and 7.0 ml of formaldehyde solution (40 wt%, 100 mmol) were dissolved in 50 ml (5 mmol) of 0.1 M NaOH solution. Then the mixture was stirred at 70\u0026deg;C for 30 min. A clear precursor solution (about 60 ml) was obtained, denoted as Solution-P.\u003c/p\u003e\u003cp\u003eFor a typical synthesis of mesoporous carbon, 5.6 g of F127 (~\u0026thinsp;0.44mmol) was dissolved in 50 ml of water. Then 60 ml of Solution-P was added into the above solution, and a clear solution was obtained. The solution turned dark red as stirred at 66\u0026deg;C for about 3 h with a rate of ~\u0026thinsp;300rpm. Subsequently, 2g the hydrated iron nitrite [Fe (NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e\u0026middot;9H\u003csub\u003e2\u003c/sub\u003eO] was added into the above solution. The solution turned from dark red to dark blue. Dark blue precipitation was observed after about 48 h. The mixture was continuously stirred at 66\u0026deg;C for additional 72 h and then stirred at 70\u0026deg;C for another 24 h. The final product was collected by sedimentation separation and filtration, washed with water and dried in air. The obtained sample was calcined at 700\u0026deg;C for 3 h in nitrogen flow to obtain mesoporous Fe/Fe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e/carbon composites materials. The heating rate was fixed at 1\u0026deg;C/min.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\u003ch2\u003e2.3. Characterization\u003c/h2\u003e\u003cp\u003ePowder X-ray diffraction (XRD) patterns were recorded on a Rigaku D/max-r system operating with Cu Ka (k\u0026thinsp;=\u0026thinsp;1.5406) radiation. High-resolution transmission electron microscopy (HRTEM) images were obtained using a JEOL JEM-2100 microscope, operating at 200 kV. For TEM measurements, the samples were prepared by dispersing the powdered products as slurry in ethanol with a ultrasonic bath for about 10 min, and then one drop of the resulting suspension was dispersed and dried on a holey carbon film on a copper grid. N\u003csub\u003e2\u003c/sub\u003e adsorption\u0026ndash;desorption isotherms were measured using Micromeritics ASAP-2010 at liquid nitrogen temperature (77 K). Prior to measurements, all samples were degassed at 473 K for 12 h. The specific surface areas were evaluated using the Brunauer-Emmett-Teller (BET) method. The pore size distribution was derived from the desorption branches of the isotherms using the Barrett-Joyner-Halenda (BJH) method.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\u003ch2\u003e2.4. Adsorption experiments for dyes\u003c/h2\u003e\u003cp\u003eAdsorption behaviors of synthesized ordered mesoporous Fe/carbon composites to dyestuff was evaluated by the qualitative filtration of fuchsin base and the adsorption isotherms for the dye-adsorbent systems.\u003c/p\u003e\u003cp\u003eThe adsorption isotherms were measured as follows. An adsorbent (Blank, active carbon (AC), PFR-Fe/C-0.10) of 5 mg was dispersed in an aqueous solution (10 mL) of the fuchsin base in guest concentration(1 g L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e ). The dispersion mixtures were shaken vigorously (160 rpm) for 24 h under precise temperature control (35℃). The adsorbents were filtered, and guest concentrations in solution at equilibrium were ascertained using UV\u0026ndash;vis spectroscopy at 553 nm for fuchsin base. The adsorption experiments were conducted at various initial concentrations of the guests, and the equilibrium guest concentrations obtained and adsorbed amounts of the guests were plotted as adsorption isotherms.\u003c/p\u003e\u003c/div\u003e"},{"header":"3. Results and discussion","content":"\u003cp\u003eThe synthesis strategy for mesostructured magnetic\u0026nbsp;PFR-Fe/C\u0026nbsp;composites is presented in Fig. 1. In step 1, appropriate amounts of F127 were introduced into the aquation to form micelles; networks were formed in F127 system via the addition of highly cross-linked polymeric PR/[Fe(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e\u0026middot;9H\u003csub\u003e2\u003c/sub\u003eO], stirring aquation at room temperature for 24 h, form PR/F127/ [Fe(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e\u0026middot;9H\u003csub\u003e2\u003c/sub\u003eO]; In step 2, the composite was carbonized under N\u003csub\u003e2\u003c/sub\u003e at 700\u0026deg;C, and Fe\u003csup\u003e3+\u003c/sup\u003e of [Fe(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e\u0026middot;9H\u003csub\u003e2\u003c/sub\u003eO]\u0026nbsp;was reduced to metallic iron. Moreover, the carbon served as a block to confine the growth of iron nanoparticles during carbonization.\u0026nbsp;It reveals that metallic nanoparticle in the mesoporous carbon matrix existed in two types: surface and in wall (fig.1).\u0026nbsp;In fig.1, (a) Schematic representation of Fe(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e3\u003c/sub\u003e\u0026middot; 9H\u003csub\u003e2\u003c/sub\u003eO)/PR structure. (b) Schematic model for the\u0026nbsp;PFR-Fe/C\u0026nbsp;structure.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;The low-angle XRD patterns of PFR-Fe/C composites with Fe/R molar ratios are presented in Fig. 2. The PFR/C-Fe-0.05 (Fig. 2a) and PFR-Fe/C-0.10 (Fig. 2b) samples show an intense diffraction peak at 2\u0026theta; range of 0.5-1\u0026deg;, which can be indexed to [100] reflection of a hexagonal mesostructure.\u003csup\u003e\u0026nbsp;\u003c/sup\u003e\u003csup\u003e[19]\u003c/sup\u003e In particular, a sharp and narrow diffraction peak at 2\u0026theta;= 0.70\u0026deg; can be observed for PFR-Fe/C-0.10, which indicates that this sample possesses well-ordered mesostructure. However, just a discernible weak peak at 2\u0026theta; = 0.68\u0026deg; was observed in the PFR-Fe/C-0.20 samples (Fig. 2c), implying that the optimal ordering of the hexagonal mesostructure can be obtained when Fe contents around Fe/R=0.1 and the ordering decreased as the Fe content was either greater or smaller than this ratio.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;Clearly, a suitable amount of Fe present in the synthesis system would lead to a highly ordered mesostructure. This phenomenon can be explained from the preparing process of the PFR-Fe/C samples. In this synthesis, when iron precursor was added into the reaction mixture containing resol and F127. And it can be used as the catalyst for cross-linking between P and F, simultaneously, P and Fe\u003csup\u003e3+\u0026nbsp;\u003c/sup\u003ehappen \u0026ldquo;chelate\u0026rdquo;.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eHowever, the presence of excess iron species might destroy the final ordering of the mesostructure，as the carbonization process occur redox reaction.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe wide-angle XRD patterns (Fig. 3) exhibit a resolved diffraction peaks at 2\u0026theta;= 43.5\u0026deg; and a intense diffraction peak at 35.4\u0026deg; for\u0026nbsp;PFR-Fe/C-0.10, which are in accordance with the (110) diffraction of body-centered cubic (bcc) \u0026alpha;-Fe (JCPDS card No. 06-0696) and the (311) diffraction of \u0026gamma;-Fe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e (JCPDS card No. 00-039-1346), respectively. It reveals that the iron species in the mesoporous carbon matrix exists in two states: metallic Fe and \u0026gamma;-Fe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e. According to Hoch et al.,\u003csup\u003e\u0026nbsp;[27]\u003c/sup\u003e iron nanoparticles (20-100 nm diameter) supported on carbon (C\u0026ndash;Fe\u003csup\u003e0\u003c/sup\u003e) can be synthesized by carbothermal reduction of iron salts and carbon black under inert atmosphere, and the threshold temperature is 600\u0026deg;C. Here, PFR-Fe/C was synthesized through \u0026nbsp;\u003c/p\u003e\n\u003cp\u003ecarbonization process at the temperature as high as 700\u0026deg;C. Therefore, it can be believed that all Fe species can be reduced to Fe nanoparticles. In this study, the existence of \u0026gamma;-Fe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u0026nbsp;\u003c/sub\u003emay be due to the fact that metallic Fe possesses extremely high reactivity and thus can be easily oxidized to iron oxides when exposed in the air.\u003csup\u003e\u0026nbsp;[21]\u003c/sup\u003e Furthermore, when the ratio of Fe/R is beyond 0.10, an intensive diffraction peak at\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e2\u0026theta;= 26\u0026deg;, along with 3 resolved diffraction peaks at 2\u0026theta;= 43\u0026deg;, 54\u0026deg;, and 78\u0026deg; can be observed in the resulting PFR-Fe/C composites, which can be indexed to the (002), (101), (004), and (110) diffraction peak for typical graphite-like carbon, respectively. \u003csup\u003e[28]\u003c/sup\u003e The results indicate that the prepared materials are graphitized during carbonization at 700 \u0026deg;C which is much lower than graphitized temperature of pure OMC.\u003csup\u003e\u0026nbsp;\u003c/sup\u003e\u003csup\u003e[29]\u003c/sup\u003e The lower graphitized temperature of PFR-Fe/C is due to the existence of the iron nanoparticles. It is well known that the nanosized metals such as Fe, Co, Ni, Mo can accelerate the development of graphitic structure of carbon when they are heat-treated together in inert gas atmosphere.\u003csup\u003e[30]\u003c/sup\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe mesostructures of the PFR-Fe/C-0.10 sample and the distribution of iron species in the final materials are investigated with TEM. As shown in\u0026nbsp;Fig.\u0026nbsp;4, iron species distributed uniformly in resol before calcine (Fig. 4A), parallel channels with a d spacing of about 10 nm are clearly observed on PFR-Fe/C-0.10, which is consistent with the XRD results, and an orderly arranged strip-like channels structure can also be observed (Fig. 4B). The finger-like column-shaped structure can also be observed from edges of strip-like channels structure, although the regularity is not very good, indicating that iron species were introduced in PR polymerization. (Fig. 4C), In order to further understand the existing state of iron species in OMC, detailed HRTEM analysis was performed (Fig. 4D). We have randomly observed many particles which were embedded in OMC or exposed on its surface. It can also be found that the nanoparticles, the dark spots, were dominantly dispersed on the walls of the OMC, They are iron as a d spacing of about 2-3 \u0026Aring; are clearly observed. For the samples with lower Fe contents, the particle size is smaller. When the Fe/R molar ratio increased to 0.10 or more, bigger particles with the diameter of 20-30 nm were obtained owning to aggregation of small nanoparticles. Nevertheless, the size of these incorporated nanoparticles is much smaller than that of support-free nanoparticles.\u003csup\u003e\u0026nbsp;[31]\u003c/sup\u003e Therefore, we conclude that OMC materials not only stabilize the Fe nanoparticles by avoiding their aggregation to some extent, but also confine the growth of nanoparticles. Furthermore, as shown in these images, the ordered structures of PFR-Fe/C composites with highly dispersed nanoparticles can be maintained Fe/R molar ratio up to 0.10.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThese HRTEM images illustrate the perfect arrangements of the atomic layers and lack of defects. The lattice plane distance in\u0026nbsp;Fig. 4D\u0026nbsp;is 2.03\u0026Aring;, which is consistent with the [110] plane of the \u0026alpha;-Fe (JCPDS card No. 06-0696).\u0026nbsp;From the above analysis, it reveals that iron species in the mesoporous carbon matrix existed in two states: metallic Fe and \u0026gamma;-Fe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e. In principle, when carbonaceous materials containing metallic salts were heat-treated under inert atmosphere, PF polymers were carbonized and meanwhile the metallic salts first decomposed to metallic oxides. With the increasing temperature, metallic oxides were gradually reduced to metallic elements by carbonaceous materials. As reported by Chen et al., iron oxides existed in the bores of carbon nanotubes or on its outer surface can be reduced to metallic Fe when heat-treated temperature reached 800\u0026deg;C. \u003csup\u003e[33]\u003c/sup\u003e Owing to the fact that metallic Fe particles are extremely active and prone to be oxidized by air at room temperature, Fe species located on the surface of OMC mostly exist as \u0026gamma;-Fe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u0026nbsp;\u003c/sub\u003eparticles while Fe species buried in the walls of OMC dominantly present as metallic Fe particles. The \u0026gamma;-Fe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e particles supported on the surface of OMC together with the carbon matrix, probably can protect the bcc-Fe particles embedded in the walls of OMC from oxidation. Fig. 5 shows N\u003csub\u003e2\u003c/sub\u003e sorption isotherms and pore size distribution of the PFR-Fe/C-0.10 composite. It exhibits typical type IV isotherms with an obvious H3-type hysteresis loop, indicating the mesoporous structures of the materials. The sharp inflections \u0026nbsp;between the relative pressures p/p\u003csub\u003e0\u003c/sub\u003e=0.4-0.8 in these isotherms correspond to capillary condensation within uniform mesopores. The pore size distributions are very narrow, centering at around 6.78 nm for PFR-Fe/C-0.10 composite. PFR-Fe/C-0.10 has a surface area of 572 m\u003csup\u003e2\u003c/sup\u003e/g and pore volume of 0.70cm\u003csup\u003e3\u003c/sup\u003e/g. These N\u003csub\u003e2\u003c/sub\u003e adsorption-desorption data are in well agreement with the Low-angle XRD (Fig. 2) and TEM (Fig. 4) results. Obviously, the moderate amount iron precursor is favorable to the formation of a well-ordered mesoporous structure.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eWe want to know whether it possesses high adsorbility for fuchsin base. Many industries use dyes to color their products and discharge their waste in water which directly pollute the soil, water, plants and all living systems in the environment. Fuchsin base is an organic dyes used in high frequency. Thereby, we investigated the adsorbility of PFR-Fe/C-0.10 to fuchsin base in water as seen in Fig. 5.\u0026nbsp;An adsorbent (Blank, AC,\u0026nbsp;PFR-Fe/C-0.10) of 5 mg was dispersed in an aqueous solution (10 mL) of the fuchsin base in guest concentration(1 g L\u003csup\u003e-1\u003c/sup\u003e ). The dispersion mixtures were shaken vigorously (160 rpm) for 24 h under precise temperature control (35℃). The result indicated PFR-Fe/C-0.10 completely removed fuchsin base from water, while the AC tested materials were not very effective for removal of the dyes. It is clearly observed that the volume of solution decolored by PFR-Fe/C-0.10) is bigger than AC tested materials. Adsorption processes have attained great importance as an environmental point of view that they can remove toxic compounds and easy separation procedure from industrial waste water. The results have shown that PFR-Fe/C-0.10 material has a high adsorption capacity for fuchsin base and this material may be found useful as a sorbent in waste water treatments.\u003c/p\u003e"},{"header":"4. Conclusions","content":"\u003cp\u003eHighly ordered Fe-containing mesostructure carbon materials can be directly prepared using soft templating routes without the addition of mineral acids. The acidity self-generated by the iron precursor should be enough to catalyze the polymerization of PF. The optimal ordering mesostructure can be obtained when the Fe/R molar ration is around 0.1. The iron species are spontaneously reduced to metallic iron by carbonaceous materials during carbonization. Fe species located on the surface of OMC mostly present as γ-Fe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e particles while Fe species buried in the walls of OMC dominantly as metallic Fe particles due to extreme reactivity of metallic iron. The resulting materials possess specific activity for catalytic wet peroxide oxidation of phenol in solution. It is believed that the easy soft templating synthesis approach reported here can be readily expanded its scope to synthesize other metals containing OMC materials. Moreover, such highly ordered mesoporous PFR-Fe/C composites may be applied in the fields of separation, catalysis, and environment remediation.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eJ.T.L. and J.L. wrote the main manuscript text and X.K.L., L.M.S prepared figures 1, G.Z., L.C.W and P.N.L prepared figures 2-7. All authors reviewed the manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgments\u003c/h2\u003e\u003cp\u003eThe work is supported by Xi'an Science and Technology Program (No. 23GXFW0081-04), the National Science Foundation of China (21541009), (21706209), the Industrial research project of Science and Technology Department of Shaanxi Province (No. 2013K09-25) and Education Department of Shaanxi provincial Government Project Foundation (2013JK0665), and the Science \u0026amp; Technology Project Foundation Xi\u0026rsquo;an (No. 2017GY-126).\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eT. Yu, Y. H. Deng, L. Wang, R. L. Liu, L. J. Zhang, B. Tu and D. Y. Zhao, Adv. Mater., 2007, 19, 2301.\u003c/li\u003e\n \u003cli\u003eA. H. Lu, W. Schmidt, N. Matoussevitch, H. Bonnemann, B. Spliethoff, B. Tesche, E. Bill, W. Kiefer and F. Sch\u0026euro;uth, Angew. Chem., Int. Ed., 2004, 43, 4303.\u003c/li\u003e\n \u003cli\u003eJ. Lee, S. M. Jin, Y. Hwang, J. G. Park, H. M. Park and T. Hyeon, Carbon, 2005, 43, 2536.\u003c/li\u003e\n \u003cli\u003eP. Gao, A. Q. Wang, X. D. Wang and T. Zhang, Chem. Mater., 2008, 20, 1881.\u003c/li\u003e\n \u003cli\u003eC. D. Liang, Z. J. Li and S. Dai, Angew. Chem., Int. Ed., 2008, 47, 3696.\u003c/li\u003e\n \u003cli\u003eY. Wan, Y. F. Shi and D. Y. Zhao, Chem. Mater., 2008, 20, 932.\u003c/li\u003e\n \u003cli\u003eR. Ryoo, S. H. Joo and S. Jun, J. Phys. Chem. B, 1999, 103, 7743.\u003c/li\u003e\n \u003cli\u003eC. D. Liang, K. L. Hong, G. A. Guiochon, J. W. Mays and S. Dai, Angew. Chem., Int. Ed., 2004, 43, 5785.\u003c/li\u003e\n \u003cli\u003eS. Tanaka, N. Nishiyama, Y. Egashira and K. Ueyama, Chem. Commun., 2005, (16), 2125.\u003c/li\u003e\n \u003cli\u003eY. Meng, D. Gu, F. Q. Zhang, Y. F. Shi, H. F. Yang, Z. Li, C. Z. Yu, B. Tu and D. Y. Zhao, Angew. Chem., Int. Ed., 2005, 44, 7053.\u003c/li\u003e\n \u003cli\u003eF. Q. Zhang, Y. Meng, D. Gu, Y. Yan, C. Z. Yu, B. Tu and D. Y. Zhao, J. Am. Chem. Soc., 2005, 127, 13508.\u003c/li\u003e\n \u003cli\u003eY. Wan, H. F. Yang and D. Y. Zhao, Acc. Chem. Res., 2006, 39, 423.\u003c/li\u003e\n \u003cli\u003eA. H. Lu and F. Sch\u0026euro;uth, Adv. Mater., 2006, 18, 1793.\u003c/li\u003e\n \u003cli\u003eJ. Lee, J. Kim and T. Hyeon, Adv. Mater., 2006, 18, 2073.\u003c/li\u003e\n \u003cli\u003eP. A. Bazula, A. H. Lu, J. J. Nitz and F. Sch\u0026euro;uth, Microporous Mesoporous Mater., 2008, 108, 266.\u003c/li\u003e\n \u003cli\u003eD. W. Wang, F. Li, M. Liu and H. M. Cheng, New Carbon Mater., 2007, 22, 307.\u003c/li\u003e\n \u003cli\u003eJiansheng Li, Juan Gu, Huijun Li, Yi Liang, Yanxia Hao, Xiuyun Sun, Lianjun Wang, Synthesis of highly ordered Fe- containing mesoporous carbon materials using soft templating routes. Microporous and Mesoporous Materials 128 (2010) 144.\u003c/li\u003e\n \u003cli\u003eR. Liu, Y. Ren, Y. Shi, F. Zhang, L. Zhang, B. Tu, D.Y. Zhao, Chem. Mater. 20 (2008) 1140.\u003c/li\u003e\n \u003cli\u003eP. Gao, A. Wang, X. Wang, T. Zhang, Chem. Mater. 20 (2008) 1881.\u003c/li\u003e\n \u003cli\u003eP. Gao, A.W. Wang, X.D. Wang, T. Zhang, Catal. Lett. 125 (2008) 289.\u003c/li\u003e\n \u003cli\u003eD.L. Huber, Small 1 (2005) 482.\u003c/li\u003e\n \u003cli\u003eR. Fernandez-Pacheco, M. Arruebo, C. Marquina, R. Ibarra, J. Arbiol, J. Santamaria, Nanotechnology 17 (2006) 1188.\u003c/li\u003e\n \u003cli\u003eW. Chen, Z.L. Fan, X.L. Pan, X.H. Bao, J. Am. Chem. Soc. 130 (2008) 9414.\u003c/li\u003e\n \u003cli\u003eJ.T. Nurmi, P.G. Tratnyek, V. Sarathy, D.R. Baer, J.E. Amonette, K. Pecher, C.M. Wang, J.C. Linehan, D.W. Matson, R.L. Penn, M.D. Driessen, Environ. Sci. Technol. 39 (2005) 1221.\u003c/li\u003e\n \u003cli\u003eX. Yuan, W. Xing, S. Zhuo, Z. Han, G. Wang, X. Gao, Z. Yan, Micropor. Mesopor. Mater. 117 (2009) 678.\u003c/li\u003e\n \u003cli\u003eZ. Gu, B. Deng, J. Yang, Micropor. Mesopor. Mater. 102 (2007) 265.\u003c/li\u003e\n \u003cli\u003eL.B. Hoch, E.J. Mach, B.W. Hydutsky, J.M. Hershman, J.M. Skluzacek, T.E. Mallouk, Environ. Sci. Technol. 42 (2008) 2600.\u003c/li\u003e\n \u003cli\u003eM. Sevilla, A.B. Fuertes, Carbon 44 (2006) 468.\u003c/li\u003e\n \u003cli\u003eX. Wang, C. Liang, S. Dai, Langmuir 24 (2008) 7500.\u003c/li\u003e\n \u003cli\u003eW. Weisweiler, N. Subramanian, B. Terwiesch, Carbon 9 (1971) 755.\u003c/li\u003e\n \u003cli\u003eC.B. Wang, W.X. Zhang, Environ. Sci. Technol. 31 (1997) 2154.\u003c/li\u003e\n \u003cli\u003eR.P. Hodgkins, A. Ahniyaz, K. Parekh, L.M. Belova, L. Bergstrom, Langmuir 23 8838.\u003c/li\u003e\n \u003cli\u003eW. Chen, X.L. Pan, M.G. Willinger, D.S. Su, X.H. Bao, J. Am. Chem. Soc. 128 3136.\u003c/li\u003e\n \u003cli\u003eA. Santos, P. Yustos, A. Quintanilla, S. Rodriguez, F. Garcia-Ochoa, Appl. Catal. B 39 (2002) 97.\u003c/li\u003e\n \u003cli\u003eJ. Barrault, M. Abdellaoui, C. Bouchoule, A. Majeste, J.M. Tatibouet, A. Louloudi, N. Papayannakos, N.H. Gangas, Appl. Catal. B 27 (2000) 225.\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":"Iron, Mesoporous carbon, Synthesis, Soft templating","lastPublishedDoi":"10.21203/rs.3.rs-7392990/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7392990/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eOrdered mesoporous PFR-Fe/C composites have been synthesized via a ‘‘one-pot’’ assembly strategy associated with a direct carbonization process by using phenolic resol (PR) as a carbon source, inorganic salt hydrated iron nitrite as an iron source and amphiphilic triblock copolymer Pluronic F127 as a template. The main strategy of this approach is to use the iron precursors as the coordinationcenter with phenol. The obtained mesoporous Fe/Fe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e/carbon composites (PFR/C-Fe) exhibit uniform pore sizes about 6.78 nm, high specific surface areas about 572 m\u003csup\u003e2\u003c/sup\u003e g\u003csup\u003e-1\u003c/sup\u003e, and high pore volumes 0.70 cm\u003csup\u003e3\u003c/sup\u003e g\u003csup\u003e-1\u003c/sup\u003e. With this facile ‘‘one-pot’’ assembly approach, one can incorporate as high as about 30 wt % of iron in the composites. The resultant materials were characterized using nitrogen sorption, X-ray diffraction, and transmission electron microscopy. It was found that the final products with a highly ordered mesostructure were obtained when the Fe/R ratio was around 1:6. Especially, the increased iron content induces the enlarged particle sizes of the iron nanocrystals, together with a high dispersion in the amorphous carbon framework, but the ordering decreased. Iron species in the mesoporous carbon matrix existed in two states, metallic Fe and α-Fe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e. Metallic Fe nanoparticles are dominantly buried in the walls of the mesoporous carbon while α-Fe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e nanoparticles are mostly located on the surface. When the iron particles have sizes larger than the mesopore wall thickness, they can extend from the carbon walls into mesopore channels, and hence bring a rougher pore surface and a lower degree of mesostructure regularity. These mesoporous Fe/Fe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e/carbon composites materials composites with high surface area, large pore size and super paramagnetic property show excellent adsorption properties for bulky dye fuchsin base. The excellent magnetic materials makes it useful in magnetic separation.\u003c/p\u003e","manuscriptTitle":"One-step Synthesis of highly ordered mesoporous Fe/carbon composites using soft templating routes","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-03 09:58:16","doi":"10.21203/rs.3.rs-7392990/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":"23c11df6-b274-4be6-8521-bf09d45945a8","owner":[],"postedDate":"September 3rd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-09-21T11:38:23+00:00","versionOfRecord":[],"versionCreatedAt":"2025-09-03 09:58:16","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7392990","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7392990","identity":"rs-7392990","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}