Fabrication of Black In2O3 with Dense Oxygen Vacancy through Dual Functional Carbon Doping for Enhancing Photothermal CO2 Hydrogenation

Fabrication of Black In2O3 with Dense Oxygen Vacancy through Dual Functional Carbon Doping for Enhancing Photothermal CO2 Hydrogenation | 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 Article Fabrication of Black In2O3 with Dense Oxygen Vacancy through Dual Functional Carbon Doping for Enhancing Photothermal CO2 Hydrogenation Yuhang Qi, Jiawei Jiang, Xichen Liang, Shuxin Ouyang, Wenbo Mi, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-102590/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 Photothermocatalytic CO 2 reduction as the channel of the energy and environmental issues resolution has captured persistent attention in recent years. In 2 O 3 has been prompted to be a potential photothermal catalyst in this sector on account of unique physicochemical properties. However, different from the metal-based photothermal catalyst with the nature of efficient light-to-thermal conversion and H 2 dissociation, the wide-bandgap semiconductor needs to be modified to possess wide-wavelength-range absorption and the active surface. It remains a challenge to achieve the two aims simultaneously via single material modulation approach. In this study, one strategy of carbon doping can empower In 2 O 3 with two advantageous modifications. The carbon doping can reduce the formation energy of oxygen vacancy, which induces the generation of oxygen-vacancy-riched material. The introduction of oxygen defect levels and carbon doping levels in band gap of In 2 O 3 significantly reduces this band gap, which endows it full-spectral and intensive solar light absorption. Therefore, the carbon doped In 2 O 3 achieves effective light-to-thermal conversion and delivers a 123.6 mmol g − 1 h − 1 of CO generation rate with near-unity selectivity, as well as prominent stability in photothermocatalytic CO 2 reduction. Catalysis Energy Engineering indium oxide carbon doping oxygen vacancy photothermal catalysis CO2 reduction Figures Figure 1 Figure 1 Figure 2 Figure 2 Figure 3 Figure 3 Introduction Energy shortage could be alleviated by fuel regeneration rely on advanced technology rather than exploitation of existing sources 1-3 . Compared with the amount of emitted solar energy in one day, fossil fuel outputs seem negligible 4,5 . Mitigating the unbalanced supply and demand, photothermocatalytic technology has been proposed as a reasonable attempt 6-9 . On the other hand, CO 2 as a well-known excess substance trapped in the atmosphere, could be converted into the value-added product in both greenhouse gas reduction and synthetic chemical generation 10-12 . Typically, high purity CO from CO 2 hydrogenation via reverse water gas shift (RWGS) reaction could be used as raw material for the Fischer-Tropsch synthesis 13 , producing carbonyl-containing compounds 14 , acetamides 15 , triflate electrophiles 16 , and purifying nickel in Mond process 17 . In this way, photothermal catalytic CO 2 reduction technology can significantly reduce energy consumption and seems promising for carbon recycle, but the fabrication of high-quality catalyst is not yet mature. Single-phase In 2 O 3 is an impactful thermochemistry catalyst with high selectivity of CO, but its wide-bandgap feature (3.2 eV) leads to unfavorable traits to light absorption (it appears pale-yellow color) and photothermal transformation 18,19 , which limits its application for photothermal catalysis. To extend the limited optical adsorption, researchers make efforts on pretreated In 2 O 3 20 , such as precious metals loading 21 and nanostructure coating 22 . But the catalytic activity of photothermal CO 2 reduction remains low. On the other hand, oxygen vacancy as the active site in In 2 O 3 plays important role in CO 2 reduction reaction, it can powerfully adsorb the CO 2 molecules. The unsaturated indium atoms around the oxygen vacancy can gradually dissociate hydrogen inputs to accelerate intermediates formation, then to the products 23,24 . Therefore, to obtain a higher concentration of oxygen vacancy per unit In 2 O 3 , nanostructures with high specific surface area seem a promising approach 25-27 . Recently, we reported a novel strategy to fabricate ultrathin 2D black In 2 O 3-x nanosheet with full spectrum absorption by photo-induced defect engineering. It exhibits a maximum yield rate of 103.2 mmol g cat −1 h −1 and near-unity selectivity for CO generation 28 . While the oxygen vacancy-rich materials still face the key issue of deactivation due to the refilling of oxygen vacancy during the catalysis process 29,30 . Therefore, how to prepare catalysts of ordinary nano- and micro- particles with comprehensive advantages including superior photothermal conversion efficiency, high concentration of active sites, and long-term stability is still in exploration. In this work, we report that a dual functional doping of carbon in In 2 O 3 through cost-effective hydrothermal synthesis for highly effective photothermal CO 2 reduction (Scheme 1a). Experimental data and simulation calculations have consistently confirmed that doped carbon works as an interstitial atom inserted in the lattice, which results in both the bandgap reduction to extend light absorption to the full spectrum and the formation of high-centration and stable oxygen vacancies (Scheme 1b). The wide-wavelength and intensive light absorption facilitate the effective photothermal conversion (400 °C of temperature rising in 10 mins under irradiation of 300 W Xe lamp). Besides, the decrease of formation energy of oxygen vacancy (V o ) due to the carbon doping enhances the concentration of active sites. The optimized C-In 2 O 3-x catalyst delivers a CO yield rate of 123.6 mmol g cat -1 h -1 (Table S1) and the remarkable stability with no attenuation even after 20 cycles (one hour per cycle). Therefore, manipulation of doped carbon atoms becomes an internal adjustment strategy in inducing oxygen vacancies and then modulating electron structure and surface property in the In 2 O 3 system so as to be suitable for photothermal CO 2 reduction. Results Fabrication and characterization of carbon doped In 2 O 3 In this experiment, glucose as the carbon source was introduced to prepare carbon doping In(OH) 3 (C-In(OH) 3 ) nanoparticle precursors (Figure S1 and S2) by hydrothermal reactions. After calcinating in the Ar atmosphere, the C-In(OH) 3 was dehydrated to form C-In 2 O 3-x , and the morphology remained almost unchanged. Particle size ranged from 50 to 200 nm and the particle surface was covered many small protuberances (Figure 1a) with uniformly distributed carbon (Figure S3). The 0.177 nm spacing on the high-resolution transmission electron microscope (HR-TEM) image confirmed the (440) lattice plane in the cubic In 2 O 3 crystalline phase corresponding to Fast Fourier transform (FFT) patterns with diffraction along the [110] axis (Figure 1b). The crystal structure was characterized by powder X-ray diffraction (XRD); all the peaks can be indexed into the standard In 2 O 3 PDF card (JCPDS card No.71-2194) (Figure 1c). In order to investigate the existential form of doped carbon and the relevant structural adjustment in In 2 O 3 , we simulated the most likely four modalities, including carbon atom substitution for oxygen atom (C s -O), carbon atom substitution for indium atom at two different positions (C s -In a and C s -In b ), and the interstitial carbon into the lattice of In 2 O 3 (C i ). Specific properties, formation energies, bond lengths and ionic valence, were listed in Table S2. The results revealed the interstitial carbon model had the smallest formation energy of 7.59 eV (Figure 1d) and required minimal energy injection than the other three cases. In comparison, model III, the substitution of indium at position B, had the second lowest formation energy. However, the atomic radii of carbon and indium atoms were too far apart for substitution doping to occur 31 . Therefore, we speculated the carbon atom tended to be an interstitial state to anchor into the In 2 O 3 lattice. Interstitial carbon could further affect the coordination of neighboring atoms to manipulate electronic properties. As seen from the X-ray absorption fine structure (XAFS), the In K-edge k 2 χ(k) vibrational lines presented a great difference between C-In 2 O 3-x and standard cubic In 2 O 3 , which qualitatively revealed distinct local atomic arrangements (inset of Figure 1e). In Figure 1e, the four main peaks could be regarded as In-In shell and In-O shell in the R space for refined local atomic arrangements. We found that doped carbon atoms shortened the length of In-In bonds and enlarged the length of In-O bonds (Table S3). In addition, the maximum K-edge absorption of C-In 2 O 3 was reduced to 27938.7 eV (Figure S4), indicating the generation of oxygen vacancy, the coordination number reduction of In-O and In-In, which resulted in higher disorder degrees 32,33 . Compared with standard cubic In 2 O 3 , the C-In 2 O 3 with the presence of a noticeable structure distortion helped to maintain structural stability 34,35 . Raman spectra provided more proof on local structural change and distortion of C-In 2 O 3-x (Figure S5). Distinct photon modes at 309, 407, 491, and 628 cm -1 were consistent with Raman active modes of the cubic structure In 2 O 3 36,37 , but when the carbon was doped into the In 2 O 3 lattice with different carbon doping levels, these highlighted peaks become smoother, suggesting introduced carbon disrupts original lattice structure 38 . To investigate the effect of doped carbon on the chemical state and electronic structure of In 2 O 3 , we performed X-ray photoelectron spectroscopy (XPS) characterization. From the In 3d core-level spectra (Figure 1f), the two peaks located at 443.7 eV and 451.4 eV were assigned to the In 3d 5/2 and In 3d 3/2 signals 39,40 . However, with interference from carbon, both peaks moved toward higher binding energy with an about 0.5 eV shift, confirming indium atoms did accept electrons from doped carbon. To prove the XPS results, we computed the charge difference density (isosurface value is 3 e nm -3 ) of model IV in Figure 1d and found much net gain of charge was distributed around indium atom (inset of Figure 1f). Experimental data corroborated theoretical calculation, proving that carbon was successfully anchored in the lattice of In 2 O 3 and therefore altered its original electronic structure. Photothermal CO 2 reduction performance To reveal the advantages of C-In 2 O 3 in the photothermal-driven RWGS reaction, we conducted the catalytic performance tests (Figure 2a) of the V o -poor In 2 O 3 , V o -rich In 2 O 3-x , and C-In 2 O 3-x with different carbon doping levels (Table S4). Benefiting from the richer concentration of active sites, V o -rich In 2 O 3-x had 18.2 mmol g cat -1 h -1 of CO production rate, which was three times higher than that of V o -poor In 2 O 3 . This result was consistent with the literature analyses that oxygen vacancy facilitated CO 2 adsorption to yield high RWGS reactivity 18,23,41 . When the appropriate amount of carbon was doped, the catalytic activity of C-In 2 O 3-x -3 achieved six-fold enlargement compared with V o -rich In 2 O 3-x (123.6 mmol g cat -1 h -1 ). Low doping concentration limited light absorption capacity to enhance the photothermal conversion efficiency in endothermic RWGS reaction while high doping concentration led that extra carbon cannot anchor in the In 2 O 3 lattice and form inert “free carbon” around the In 2 O 3 nanoparticle to compete for the light energy. The more detail of the mechanism for the high activity will be discussed in next section. With the optimal sample, the CO 2 conversion rate of C-In 2 O 3-x eventually reached 45% with near-unity CO selectivity without the production of CH 4 (Figure 2b) and the remarkable catalytic performance kept holding beyond 20 cycles in stability test (Figure 2c). The blank control test under the photothermal conditions also confirmed the doped carbon in the C-In 2 O 3-x was stable and could not be decomposed to CO 2 or CO (Figure S6). Further, the turnover number of the cyclic stability test (the amount of yield product/the amount of catalyst) was 190.56 that was much larger than 1, indicating photothermal RWGS reaction exhibits typical feature of catalysis. Mechanism and pathway of photothermal CO 2 reduction Photothermal catalysis of CO 2 reduction involves two main steps. The first step is light absorption and photothermal transformation via the active sites on the catalyst surface (local temperature effect); the second is CO 2 adsorption and subsequent catalytic process 28 . In the first step, the catalysts are required to possess broader spectral coverage to maximize energy absorption and energy transfer efficiency. Because the photoexcited carriers (electron-hole pairs) could heat the non-plasmonic C-In 2 O 3-x through non-radiative recombination from either Auger or Shockley-Read-Hall (i.e., trap assisted) to drive the thermally catalytic process, which rendered the mechanism for lattice vibrations and heat generation 6,42 , and powerfully assisted in lowering the photochemical activation energy 43,44 . Unlike the pale yellow of In 2 O 3 crystals or the pale gray of In 2 O 3-x , the color of C-In 2 O 3-x appeared jet black (inset of Figure 3a), having broader photon absorption ranges from 250 to 2400 nm and stronger absorption intensity. Doped carbon atoms could extend the scope to the visible light region and defect state caused by oxygen vacancy further extended it to infrared region (Figure 3a). Combined with the bandgap structure (Figure S7) and ultraviolet photoelectron spectroscopy (UPS) (Figure S8), a schematic illustration of the bandgap structure of C-In 2 O 3-x was depicted and shown in Figure S9. The band structure and density of states (DOS) of C-In 2 O 3-x regulated by doped carbon could be explained using density functional theory (DFT). In Figure S10, compared with the cubic In 2 O 3 , when an oxygen vacancy was generated around an interstitial carbon, a new defect energy level with more massive DOS emerges. In this case, the electrons can be easily excited into the conduction band through the intermediate state, thereby achieving higher photoconversion efficiency 45-47 . On the other hand, the radiative recombination competed against non-radiative recombination. After carbon doping, the fluorescence significantly quenched, demonstrating that radiative recombination of the photon-generated carriers had been suppressed by extracting the electrons (Figure S11). Therefore, the C-In 2 O 3-x system could reach near 400 °C within 10 minutes, which is far higher temperature than those of V o -poor In 2 O 3 and V o -rich In 2 O 3 -x (Figure 3b). The surface of C-In 2 O 3-x worked as a "nanoscale heat source," which absorbed the photon energy and rapidly converted it into heat that was conducted to the active sites of C-In 2 O 3-x in a short time. The next step was adsorption of gas molecules onto the surface and subsequent catalytic process. For clarity, in temperature-programmed desorption (TPD) of CO 2 , the peak at 480℃ indicated the adsorption was in the form of chemisorption via the oxygen vacancies on C-In 2 O 3-x 48,49 . If the oxygen vacancy is filled under annealing in air, the adsorption capacity could be notably reduced (Figure S12). In order to prove the role of oxygen vacancy as the active site was in the catalytic process, we conducted comparative DFT calculations of In 2 O 3 and In 2 O 3 -O vac [110] slabs (Figure S13 -15). The Gibbs free energy for the intermediate *CO of RWGS reaction on In 2 O 3 slab without oxygen vacancy was 0.66 eV which was higher than the slab with oxygen vacancy (0.32 eV). Thus, a high concentration of oxygen vacancies was expected to increase the capacity of CO 2 adsorption and lower the energy barrier of photothermal CO 2 reduction RWGS reaction. Electron spin resonance spectroscopy (ESR) effectively evaluated the oxygen vacancy concentration (Figure 3c). Limited signals of V o -poor In 2 O 3 and V o -rich In 2 O 3-x were detected, while a stronger signal of C-In 2 O 3-x appeared at g=2.004, which could be explained as more concentrated electrons are trapped around the surface oxygen vacancies 50 . Next, to prove the carbon doping has a function in elevating oxygen vacancy concentration, the formation energy of oxygen vacancy was simulated (inset of Figure 3c). In non-defective In 2 O 3 crystal, the oxygen vacancy formation energy was 4.98 eV, while the energy decreased to 3.10 eV after interstitial carbon anchored into In 2 O 3 lattice (Table S3). Our result suggested that interstitial carbon assembled with oxygen vacancy to form a higher concentration active sites, thereby pushing forward the RWGS reaction. We then performed the in-situ Fourier Transform Infrared (FTIR) characterization in a flow cell to investigate the catalytic pathway of RWGS reaction on the active sites of C-In 2 O 3-x . As displayed in Figure 3d, the C-In 2 O 3-x exhibited OH stretching band within the range 3400-3730 cm -1 . Peaks located at 1500 and 1390 cm −1 were identified as chemisorbed CO 2 and H 2 molecules, as well as bicarbonate (HCO 3 − ) and carbonate (CO 3 − ) formation. The detectable peak at 2894 cm −1 was attributed to bending vibration δ(CH). Here, the peaks corresponding to crucial intermediate methoxy (H 3 CO*) in the spectra were at 2839 and 1090 cm −1 , and COOH* were at 1578 and 1232 cm −1 . Therefore, the incoming electrons coupled with resident protons reduced the amount of CO 2 molecules at the active sites, oxygen vacancy, then formed COOH* and H 3 CO* intermediates and transferred into CO* consistently. Simultaneously, the peak at 2107 cm −1 and 1643 cm −1 were the diagnostic vibrational modes of CO and H 2 O respectively, indicating the reaction pathway that features CO* as the intermediate from carboxyl through the RWGS reaction 51-54 . In general, oxygen vacancy with doped carbon as active sites effectively activated CO 2 molecules and stabilized the intermediates, so as to reduce the activation energy and promote photothermal CO 2 reduction (Figure 3e). Discussion In summary, photothermal catalytic CO 2 reduction is a promising technology to alter the traditional thermo-catalytic reaction, which thermodynamically improves activity under light conditions without additional energy input. The dual-function carbon doping is a feasible option to enhance and stabilize photothermal catalyst activity of In 2 O 3 . Doped carbon is more conducive to the light absorption and the photothermal conversion efficiency improvement; benefiting from formation energy reduction of oxygen vacancy, high concentration active sites are obtainable. As a result, the C-In 2 O 3-x has 123.6 mmol g -1 h -1 of CO production rates and nearly 100% selectivity. This work demonstrates that the microstructure modulation of crystal defect in catalyst can significantly enhanced the utilization of solar light and then to drive efficient and stable catalytic reaction, which achieves high-performance solar-to-chemical energy conversion. Experimental Section Materials : Synthesis of V o -poor In 2 O 3 and V o -rich In 2 O 3-x nano partials: First, 1 mmol indium nitrate was added into 60 mL deionized water, magnetically stirred for 20 min, then mixed with 3 mmol urea followed by another 10 min stirring. After, the mixture was transferred into a 100 mL Teflon-lined stainless-steel autoclave, sealed and maintained at 140°C for 12 hours. The whole system naturally cools down to room temperature. After centrifuging the mixture, the final product was collected, washed with distilled water and ethanol several times and then dried in air at 60℃. Calcination is at 600 °C for 2 h in air and H 2 -Ar with a heating rate of 5 °C min −1 to fabricate the V o -poor In 2 O 3 and V o -rich In 2 O 3-x . The synthesis procedure for C-In 2 O 3 is similar to that of V o -poor In 2 O 3 and V o -rich In 2 O 3-x , except that 1 mmol of indium nitrate, 3 mmol urea and different amounts of glucose (0.1, 0.2, 0.3, 0.4, and 0.5 g) were simultaneously added into the starting solution for hydrothermal synthesis, and calcination at 600 °C for 2 h in Ar. Reaction condition and activity evaluation: Photothermal CO 2 conversion by H 2 was carried out in a batch type reaction system with a total volume of 330 ml. After evacuation of reaction system, CO 2 and H 2 (the molar ratio of H 2 to CO 2 is 1:1) were injected. A 300W Xe lamp was used as irradiation source to drive the photothermal CO 2 conversion. The light intensity is 2.98 W cm -2 . The temperature of catalyst surface is measured by the infrared thermometer, and the reflectance coefficient is 0.78. For all experiments, 0.05 g of sample was used and spread onto a round shape air-permeable quartz fiber filter with the area of 7 cm 2 . The quartz fiber filter film is fixed on the stage inside the reactor. The tip of thermometer was maintained an intimate contact with the sample (thickness of catalyst powder is about 1~2 mm). The contents of CO 2 and CO in the reaction system were sampled and measured with a gas chromatograph (GC-2014, Shimadzu) equipped with a methanizer and flame ionization detector according to the standard curves. Sample characterization: XRD patterns were recorded on an X-Pert diffractometer equipped with graphite monochromatized Cu-K radiation. The morphologies were characterized by field-emission SEM (Hitachi, s4800) and TEM (JEOL, 2100F). The diffuse reflection spectra of catalysts were measured by UV–vis-NIR spectrophotometer (Shimadzu, UV-3600) from 220 to 2400 nm. Chemical valence of the surface was analyzed by XPS (Escalab 250Xi, Thermo Scientific, America). The PL properties of materials were investigated by PL spectra (Horiba Fluorolog-3) with the excitation light wavelength of 350 nm. The ESR spectra measurements were executed on JES-FA200 X-band spectrometer. The catalyst temperature was probed by a digital thermometer (Custom, CT-1200D). Raman spectra were recorded by Horiba (Xplora Plus) instrument. The pore size distribution was determined with a surface area analyzer (BEL Sorp-II mini, BEL Japan Co., Japan) by the BET method. The FTIR spectrum was executed on Nicolet 6700. In situ FTIR spectra have been recorded by a Nicolet 6700 Fourier transform instrument, using conventional IR cells connected to a gas manipulation apparatus. XAS measurement for the In K-edge was performed in fluorescence mode on beamline 20-BM-B with electron energy of 7 GeV and an average current of 100 mA which is located in the Advanced Photon Source at Argonne National Laboratory. Declarations Acknowledgements This work received financial support from the National Natural Science Foundation of China (Grants 21972052 and 21633004) and JSPS KAKENHI of Japan (Grant Number JP18H02065). 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Additional Declarations There is NO Competing Interest. Supplementary Files GUnpublishedWorksQiYHXXXXXXXXXNatureCommunicationsFinalVersionbeforeSubmissionSupplementaryInformation.docx Supplementary Information GUnpublishedWorksQiYHXXXXXXXXXNatureCommunicationsFinalVersionbeforeSubmissionSupplementaryInformation.docx Supplementary Information Scheme1.png Scheme 1. Schematic illustration of the formation mechanism, catalytic process and advantages for CO2 photothermal reduction into CO over C-In2O3-x. Scheme1.png Scheme 1. Schematic illustration of the formation mechanism, catalytic process and advantages for CO2 photothermal reduction into CO over C-In2O3-x. 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. 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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-102590","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":4399250,"identity":"ca8f9246-7003-43be-a6cb-ca9e4cdd6c60","order_by":0,"name":"Yuhang Qi","email":"","orcid":"","institution":"Tianjin University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Yuhang","middleName":"","lastName":"Qi","suffix":""},{"id":4399251,"identity":"70ba6d8d-cd9a-4be0-9c25-6db5d51f016b","order_by":1,"name":"Jiawei Jiang","email":"","orcid":"","institution":"Tianjin University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Jiawei","middleName":"","lastName":"Jiang","suffix":""},{"id":4399252,"identity":"827afda8-bc63-477b-9526-5d09a27e46a0","order_by":2,"name":"Xichen Liang","email":"","orcid":"","institution":"University of California","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Xichen","middleName":"","lastName":"Liang","suffix":""},{"id":4399253,"identity":"6134a938-2fa8-4188-9cbe-0571a5aad4db","order_by":3,"name":"Shuxin Ouyang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA3klEQVRIiWNgGAWjYLCCDwwMPHxw3gEidDDOAGphI0kLMw+QIF4Lv0T6M2nbHDsZNgbmh58L2xjk+G4kMH4uwKNFckaOsXHutmSgw9iMpWe2MRhL3khglp6BR4vBjRzGx7nbmIFaeNiYedsYEjfcSGADOxW3lvQHhy231cO11BOhJcHwMeO2w3AtCQaEtEj2vDE27N12HKge6BeecxKGM888bJbGp4WfPf2ZxM9t1fb87M0PP/OU2cjzHU8++BmfFgaBBCiDGUxKADFjAz4NQGsO4JcfBaNgFIyCUcAAAF8lPFZlc+G6AAAAAElFTkSuQmCC","orcid":"https://orcid.org/0000-0002-7650-1245","institution":"Central China Normal University","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Shuxin","middleName":"","lastName":"Ouyang","suffix":""},{"id":4399254,"identity":"3d57fb28-9f52-473f-9236-b9a9db508a94","order_by":4,"name":"Wenbo Mi","email":"","orcid":"https://orcid.org/0000-0002-9108-9930","institution":"Tianjin University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Wenbo","middleName":"","lastName":"Mi","suffix":""},{"id":4399255,"identity":"c1576354-d599-405f-9997-58d122cdc5c2","order_by":5,"name":"Shangbo Ning","email":"","orcid":"","institution":"Tianjin University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Shangbo","middleName":"","lastName":"Ning","suffix":""},{"id":4399256,"identity":"a5b4d434-edff-465c-9d85-8b46559ec8c7","order_by":6,"name":"Lei Zhao","email":"","orcid":"","institution":"University of California","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Lei","middleName":"","lastName":"Zhao","suffix":""},{"id":4399257,"identity":"5b57f13c-362e-4e93-a2eb-23c3f14aa5b8","order_by":7,"name":"Jinhua Ye","email":"","orcid":"https://orcid.org/0000-0002-8105-8903","institution":"National Institute for Materials Science","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Jinhua","middleName":"","lastName":"Ye","suffix":""}],"badges":[],"createdAt":"2020-11-03 20:40:43","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-102590/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-102590/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":3466885,"identity":"7492db22-9981-4590-9ea4-2da65c919a2d","added_by":"auto","created_at":"2020-11-09 16:55:21","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1053730,"visible":true,"origin":"","legend":"(a) SEM of C-In2O3-x, inset: the part of the region enclosed by the yellow square, (b) HR-TEM image of C-In2O3-x, inset: The Fast Fourier transform corresponding yellow square, (c) XRD patterns of Vo-poor In2O3, Vo-rich In2O3-x and C-In2O3-x, (d) Formation energy of Cs-O, Cs-Ina, Cs-Inb and Ci, (e) In K-edge extended XAFS oscillation function k2χ(k), Inset: the corresponding Fourier-transformed data for standard In2O3 and C-In2O3-x, (f) XPS spectra of the In 3d core level peak regions of C-In2O3-x, inset: charge difference density of In2O3 with one C atom interstitial with one O atom vacancy.","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-102590/v1/72ca20a5f82dc3001ae29d52.png"},{"id":3466878,"identity":"c1a58a22-48d2-4c52-b039-b0e8e63b6a99","added_by":"auto","created_at":"2020-11-09 16:55:15","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1053730,"visible":true,"origin":"","legend":"(a) SEM of C-In2O3-x, inset: the part of the region enclosed by the yellow square, (b) HR-TEM image of C-In2O3-x, inset: The Fast Fourier transform corresponding yellow square, (c) XRD patterns of Vo-poor In2O3, Vo-rich In2O3-x and C-In2O3-x, (d) Formation energy of Cs-O, Cs-Ina, Cs-Inb and Ci, (e) In K-edge extended XAFS oscillation function k2χ(k), Inset: the corresponding Fourier-transformed data for standard In2O3 and C-In2O3-x, (f) XPS spectra of the In 3d core level peak regions of C-In2O3-x, inset: charge difference density of In2O3 with one C atom interstitial with one O atom vacancy.","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-102590/v1/dd84e1aed42136be72083285.png"},{"id":3466888,"identity":"f3f7aeec-3b88-4eac-91c1-e2713212f467","added_by":"auto","created_at":"2020-11-09 16:55:21","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":226401,"visible":true,"origin":"","legend":"(a) CO production rates of Vo-poor In2O3, Vo-rich In2O3-x and C-In2O3-x with different carbon content, (b) photothermal CO2 conversion test and selectivity of C-In2O3-x-3. Reaction condition: 50 mg catalysts, H2: CO2=1:1, 300 W Xenon lamp, (c) Cyclic stability testing of C-In2O3-x-3.","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-102590/v1/57571c583adc3c6ea9cc4c1f.png"},{"id":3466881,"identity":"fd13d17a-262f-412a-9f05-f62da00bdcc1","added_by":"auto","created_at":"2020-11-09 16:55:15","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":226401,"visible":true,"origin":"","legend":"(a) CO production rates of Vo-poor In2O3, Vo-rich In2O3-x and C-In2O3-x with different carbon content, (b) photothermal CO2 conversion test and selectivity of C-In2O3-x-3. Reaction condition: 50 mg catalysts, H2: CO2=1:1, 300 W Xenon lamp, (c) Cyclic stability testing of C-In2O3-x-3.","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-102590/v1/c687d6bbc066bed99ab5d18a.png"},{"id":3466889,"identity":"f269a36f-5668-481f-86e0-500a22693e6e","added_by":"auto","created_at":"2020-11-09 16:55:22","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":358914,"visible":true,"origin":"","legend":"(a) UV- visible -NIR spectra, Inset: digital photo, (b) Temperature monitoring of photothermal conversion of CO2 system, (c) Electron spin resonance spectra, Inset: Oxygen vacancy formation energy of perfect In2O3 and Ci-In2O3, (d) in situ FT-IR spectra, (e) Advantages for CO2 photothermal reduction into CO over the C-In2O3-x.","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-102590/v1/1f784654e3b1d58a678c5742.png"},{"id":3466882,"identity":"a9040b31-a0ea-48bd-95bc-7d365b8e53af","added_by":"auto","created_at":"2020-11-09 16:55:16","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":358914,"visible":true,"origin":"","legend":"(a) UV- visible -NIR spectra, Inset: digital photo, (b) Temperature monitoring of photothermal conversion of CO2 system, (c) Electron spin resonance spectra, Inset: Oxygen vacancy formation energy of perfect In2O3 and Ci-In2O3, (d) in situ FT-IR spectra, (e) Advantages for CO2 photothermal reduction into CO over the C-In2O3-x.","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-102590/v1/b437c7c26751101b76b23c16.png"},{"id":13613053,"identity":"efc50a5b-0cc5-4c36-a309-af16ab1f00c5","added_by":"auto","created_at":"2021-09-17 06:35:36","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2437676,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-102590/v1/6c1e2c17-01d3-4e1a-b279-9ed07b835a24.pdf"},{"id":3466886,"identity":"5ade87c4-02fd-466b-9d4b-042e6d005405","added_by":"auto","created_at":"2020-11-09 16:55:21","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":3103666,"visible":true,"origin":"","legend":"Supplementary Information","description":"","filename":"GUnpublishedWorksQiYHXXXXXXXXXNatureCommunicationsFinalVersionbeforeSubmissionSupplementaryInformation.docx","url":"https://assets-eu.researchsquare.com/files/rs-102590/v1/b62d7fa6623dcd4aa0942d35.docx"},{"id":3466879,"identity":"72a3428c-1baa-4fd1-9012-8ef4ecf29f82","added_by":"auto","created_at":"2020-11-09 16:55:15","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":3103666,"visible":true,"origin":"","legend":"Supplementary Information","description":"","filename":"GUnpublishedWorksQiYHXXXXXXXXXNatureCommunicationsFinalVersionbeforeSubmissionSupplementaryInformation.docx","url":"https://assets-eu.researchsquare.com/files/rs-102590/v1/9d184535d73c9857873fa6e9.docx"},{"id":3466887,"identity":"9f1f5bc7-69fc-4599-be78-d2b4848f9e76","added_by":"auto","created_at":"2020-11-09 16:55:21","extension":"png","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":345002,"visible":true,"origin":"","legend":"Scheme 1. Schematic illustration of the formation mechanism, catalytic process and advantages for CO2 photothermal reduction into CO over C-In2O3-x.","description":"","filename":"Scheme1.png","url":"https://assets-eu.researchsquare.com/files/rs-102590/v1/7c99646d8cc28a70bd45cf70.png"},{"id":3466880,"identity":"31fb13c7-caf9-445d-a373-78c04b1f227b","added_by":"auto","created_at":"2020-11-09 16:55:15","extension":"png","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":345002,"visible":true,"origin":"","legend":"Scheme 1. Schematic illustration of the formation mechanism, catalytic process and advantages for CO2 photothermal reduction into CO over C-In2O3-x.","description":"","filename":"Scheme1.png","url":"https://assets-eu.researchsquare.com/files/rs-102590/v1/0c60327c419a9912edb5d387.png"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Fabrication of Black In2O3 with Dense Oxygen Vacancy through Dual Functional Carbon Doping for Enhancing Photothermal CO2 Hydrogenation","fulltext":[{"header":"Introduction","content":"\u003cp\u003eEnergy shortage could be alleviated by fuel regeneration rely on advanced technology rather than exploitation of existing sources \u003csup\u003e1-3\u003c/sup\u003e. Compared with the amount of emitted solar energy in one day, fossil fuel outputs seem negligible\u003csup\u003e4,5\u003c/sup\u003e. Mitigating the unbalanced supply and demand, photothermocatalytic technology has been proposed as a reasonable attempt\u003csup\u003e6-9\u003c/sup\u003e. On the other hand, CO\u003csub\u003e2 \u003c/sub\u003eas a well-known excess substance trapped in the atmosphere, could be converted into the value-added product in both greenhouse gas reduction and synthetic chemical generation\u003csup\u003e10-12\u003c/sup\u003e. Typically, high purity CO from CO\u003csub\u003e2\u003c/sub\u003e hydrogenation via reverse water gas shift (RWGS) reaction could be used as raw material for the Fischer-Tropsch synthesis\u003csup\u003e13\u003c/sup\u003e, producing carbonyl-containing compounds\u003csup\u003e14\u003c/sup\u003e, acetamides\u003csup\u003e15\u003c/sup\u003e, triflate electrophiles\u003csup\u003e16\u003c/sup\u003e, and purifying nickel in Mond process\u003csup\u003e17\u003c/sup\u003e. In this way, photothermal catalytic CO\u003csub\u003e2\u003c/sub\u003e reduction technology can significantly reduce energy consumption and seems promising for carbon recycle, but the fabrication of high-quality catalyst is not yet mature.\u003c/p\u003e\n\u003cp\u003eSingle-phase In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e is an impactful thermochemistry catalyst with high selectivity of CO, but its wide-bandgap feature (3.2 eV) leads to unfavorable traits to light absorption (it appears pale-yellow color) and photothermal transformation\u003csup\u003e18,19\u003c/sup\u003e, which limits its application for photothermal catalysis. To extend the limited optical adsorption, researchers make efforts on pretreated In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e20\u003c/sup\u003e, such as precious metals loading\u003csup\u003e21\u003c/sup\u003e and nanostructure coating\u003csup\u003e22\u003c/sup\u003e. But the catalytic activity of photothermal CO\u003csub\u003e2\u003c/sub\u003e reduction remains low. On the other hand, oxygen vacancy as the active site in In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3 \u003c/sub\u003eplays important role in CO\u003csub\u003e2\u003c/sub\u003e reduction reaction, it can powerfully adsorb the CO\u003csub\u003e2\u003c/sub\u003e molecules. The unsaturated indium atoms around the oxygen vacancy can gradually dissociate hydrogen inputs to accelerate intermediates formation, then to the products\u003csup\u003e23,24\u003c/sup\u003e. Therefore, to obtain a higher concentration of oxygen vacancy per unit In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, nanostructures with high specific surface area seem a promising approach\u003csup\u003e25-27\u003c/sup\u003e. Recently, we reported a novel strategy to fabricate ultrathin 2D black In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3-x\u003c/sub\u003e nanosheet with full spectrum absorption by photo-induced defect engineering. It exhibits a maximum yield rate of 103.2 mmol g\u003csub\u003ecat\u003c/sub\u003e\u003csup\u003e\u0026minus;1\u003c/sup\u003e h\u003csup\u003e\u0026minus;1\u003c/sup\u003e and near-unity selectivity for CO generation\u003csup\u003e28\u003c/sup\u003e. While the oxygen vacancy-rich materials still face the key issue of deactivation due to the refilling of oxygen vacancy during the catalysis process\u003csup\u003e29,30\u003c/sup\u003e. Therefore, how to prepare catalysts of ordinary nano- and micro- particles with comprehensive advantages including superior photothermal conversion efficiency, high concentration of active sites, and long-term stability is still in exploration.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn this work, we report that a dual functional doping of carbon in In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e through cost-effective hydrothermal synthesis for highly effective photothermal CO\u003csub\u003e2\u003c/sub\u003e reduction (Scheme 1a). Experimental data and simulation calculations have consistently confirmed that doped carbon works as an interstitial atom inserted in the lattice, which results in both the bandgap reduction to extend light absorption to the full spectrum and the formation of high-centration and stable oxygen vacancies (Scheme 1b). The wide-wavelength and intensive light absorption facilitate the effective photothermal conversion (400 \u0026deg;C of temperature rising in 10 mins under irradiation of 300 W Xe lamp). Besides, the decrease of formation energy of oxygen vacancy (V\u003csub\u003eo\u003c/sub\u003e) due to the carbon doping enhances the concentration of active sites. The optimized C-In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3-x\u003c/sub\u003e catalyst delivers a CO yield rate of 123.6 mmol g\u003csub\u003ecat\u003c/sub\u003e\u003csup\u003e-1 \u003c/sup\u003eh\u003csup\u003e-1 \u003c/sup\u003e(Table S1) and the remarkable stability with no attenuation even after 20 cycles (one hour per cycle). Therefore, manipulation of doped carbon atoms becomes an internal adjustment strategy in inducing oxygen vacancies and then modulating electron structure and surface property in the In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e system so as to be suitable for photothermal CO\u003csub\u003e2\u003c/sub\u003e reduction.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cstrong\u003eFabrication and characterization of carbon doped In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn this experiment, glucose as the carbon source was introduced to prepare carbon doping In(OH)\u003csub\u003e3\u003c/sub\u003e (C-In(OH)\u003csub\u003e3\u003c/sub\u003e) nanoparticle precursors (Figure S1 and S2) by hydrothermal reactions. After calcinating in the Ar atmosphere, the C-In(OH)\u003csub\u003e3 \u003c/sub\u003ewas dehydrated to form C-In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3-x\u003c/sub\u003e, and the morphology remained almost unchanged. Particle size ranged from 50 to 200 nm and the particle surface was covered many small protuberances (Figure 1a) with uniformly distributed carbon (Figure S3). The 0.177 nm spacing on the high-resolution transmission electron microscope (HR-TEM) image confirmed the (440) lattice plane in the cubic In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e crystalline phase corresponding to Fast Fourier transform (FFT) patterns with diffraction along the [110] axis (Figure 1b). The crystal structure was characterized by powder X-ray diffraction (XRD); all the peaks can be indexed into the standard In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e PDF card (JCPDS card No.71-2194) (Figure 1c).\u003c/p\u003e\n\u003cp\u003eIn order to investigate the existential form of doped carbon and the relevant structural adjustment in In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, we simulated the most likely four modalities, including carbon atom substitution for oxygen atom (C\u003csub\u003es\u003c/sub\u003e-O), carbon atom substitution for indium atom at two different positions (C\u003csub\u003es\u003c/sub\u003e-In\u003csub\u003ea\u003c/sub\u003e and C\u003csub\u003es\u003c/sub\u003e-In\u003csub\u003eb\u003c/sub\u003e), and the interstitial\u0026nbsp;carbon into the lattice of In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e (C\u003csub\u003ei\u003c/sub\u003e). Specific properties, formation energies, bond lengths and ionic valence, were listed in Table S2. The results revealed the interstitial carbon model had the smallest formation energy of 7.59 eV (Figure 1d) and required minimal energy injection than the other three cases. In comparison, model III, the substitution of indium at position B, had the second lowest formation energy. However, the atomic radii of carbon and indium atoms were too far apart for substitution doping to occur\u003csup\u003e31\u003c/sup\u003e. Therefore, we speculated the carbon atom tended to be an interstitial state to anchor into the In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e lattice. Interstitial carbon could further affect the coordination of neighboring atoms to manipulate electronic properties. As seen from the X-ray absorption fine structure (XAFS), the In K-edge k\u003csup\u003e2\u003c/sup\u003e\u0026chi;(k) vibrational lines presented a great difference between C-In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3-x \u003c/sub\u003eand standard cubic In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, which qualitatively revealed distinct local atomic arrangements (inset of Figure 1e). In Figure 1e, the four main peaks could be regarded as In-In shell and In-O shell in the R space for refined local atomic arrangements. We found that doped carbon atoms shortened the length of In-In bonds and enlarged the length of In-O bonds (Table S3). In addition, the maximum K-edge absorption of C-In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e was reduced to 27938.7 eV (Figure S4), indicating the generation of oxygen vacancy, the coordination number reduction of In-O and In-In, which resulted in higher disorder degrees\u003csup\u003e32,33\u003c/sup\u003e. Compared with standard cubic In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, the C-In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e with the presence of a noticeable structure distortion helped to maintain structural stability\u003csup\u003e34,35\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eRaman spectra provided more proof on local structural change and distortion of C-In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3-x\u003c/sub\u003e (Figure S5). Distinct photon modes at 309, 407, 491, and 628 cm\u003csup\u003e-1\u003c/sup\u003e were consistent with Raman active modes of the cubic structure In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e36,37\u003c/sup\u003e, but when the carbon was doped into the In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e lattice with different carbon doping levels, these highlighted peaks become smoother, suggesting introduced carbon disrupts original lattice structure \u003csup\u003e38\u003c/sup\u003e. To investigate the effect of doped carbon on the chemical state and electronic structure of In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, we performed X-ray photoelectron spectroscopy (XPS) characterization. From the In 3d core-level spectra (Figure 1f), the two peaks located at 443.7 eV and 451.4 eV were assigned to the In 3d\u003csub\u003e5/2 \u003c/sub\u003eand In 3d\u003csub\u003e3/2\u003c/sub\u003e signals\u003csup\u003e39,40\u003c/sup\u003e. However, with interference from carbon, both peaks moved toward higher binding energy with an about 0.5 eV shift, confirming indium atoms did accept electrons from doped\u0026nbsp;carbon. To prove the XPS results, we computed the charge difference density (isosurface value is 3 e nm\u003csup\u003e-3\u003c/sup\u003e) of model IV in Figure 1d and found much net gain of charge was distributed around indium atom (inset of Figure 1f). Experimental data corroborated theoretical calculation, proving that carbon was successfully anchored in the lattice of In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e and therefore altered its original electronic structure.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePhotothermal CO\u003csub\u003e2\u003c/sub\u003e reduction\u003c/strong\u003e\u003cstrong\u003e performance \u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTo reveal the advantages of C-In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e in the photothermal-driven RWGS reaction, we conducted the catalytic performance tests (Figure 2a) of the V\u003csub\u003eo\u003c/sub\u003e-poor In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, V\u003csub\u003eo\u003c/sub\u003e-rich In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3-x\u003c/sub\u003e, and C-In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3-x\u003c/sub\u003e with different carbon doping levels (Table S4). Benefiting from the richer concentration of active sites, V\u003csub\u003eo\u003c/sub\u003e-rich In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3-x\u003c/sub\u003e had 18.2 mmol g\u003csub\u003ecat\u003c/sub\u003e\u003csup\u003e-1\u003c/sup\u003e h\u003csup\u003e-1\u003c/sup\u003e of CO production rate, which was three times higher than that of V\u003csub\u003eo\u003c/sub\u003e-poor In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e. This result was consistent with the literature analyses that oxygen vacancy facilitated CO\u003csub\u003e2\u003c/sub\u003e adsorption to yield high RWGS reactivity\u003csup\u003e18,23,41\u003c/sup\u003e. When the appropriate amount of carbon was doped, the catalytic activity of C-In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3-x\u003c/sub\u003e-3 achieved six-fold enlargement compared with V\u003csub\u003eo\u003c/sub\u003e-rich In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3-x\u003c/sub\u003e (123.6 mmol g\u003csub\u003ecat\u003c/sub\u003e\u003csup\u003e-1 \u003c/sup\u003eh\u003csup\u003e-1\u003c/sup\u003e). Low doping concentration limited light absorption capacity to enhance the photothermal conversion efficiency in endothermic RWGS reaction while high doping concentration led that extra carbon cannot anchor in the In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e lattice and form inert \u0026ldquo;free carbon\u0026rdquo; around the In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3 \u003c/sub\u003enanoparticle to compete for the light energy. The more detail of the mechanism for the high activity will be discussed in next section. With the optimal sample, the CO\u003csub\u003e2\u003c/sub\u003e conversion rate of C-In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3-x\u003c/sub\u003e eventually reached 45% with near-unity CO selectivity without the production of CH\u003csub\u003e4\u003c/sub\u003e (Figure 2b) and the remarkable catalytic performance kept holding beyond 20 cycles in stability test (Figure 2c). The blank control test under the photothermal conditions also confirmed the doped carbon in the C-In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3-x\u003c/sub\u003e was stable and could not be decomposed to CO\u003csub\u003e2\u003c/sub\u003e or CO (Figure S6). Further, the turnover number of the cyclic stability test (the amount of yield product/the amount of catalyst) was 190.56 that was much larger than 1, indicating photothermal RWGS reaction exhibits typical feature of catalysis.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMechanism and pathway of photothermal CO\u003csub\u003e2\u003c/sub\u003e reduction\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePhotothermal catalysis of CO\u003csub\u003e2\u003c/sub\u003e reduction involves two main steps. The first step is light absorption and photothermal transformation via the active sites on the catalyst surface (local temperature effect); the second is CO\u003csub\u003e2 \u003c/sub\u003eadsorption and subsequent catalytic process\u003csup\u003e28\u003c/sup\u003e. In the first step, the catalysts are required to possess broader spectral coverage to maximize energy absorption and energy transfer efficiency. Because the photoexcited carriers (electron-hole pairs) could heat the non-plasmonic C-In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3-x\u003c/sub\u003e through non-radiative recombination from either Auger or Shockley-Read-Hall (i.e., trap assisted) to drive the thermally catalytic process, which rendered the mechanism for lattice vibrations and heat generation\u003csup\u003e6,42\u003c/sup\u003e, and powerfully assisted in lowering the photochemical activation energy\u003csup\u003e43,44\u003c/sup\u003e. Unlike the pale yellow of In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e crystals or the pale gray of In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3-x\u003c/sub\u003e, the color of C-In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3-x\u003c/sub\u003e appeared jet black (inset of Figure 3a), having broader photon absorption ranges from 250 to 2400 nm and stronger absorption intensity. Doped carbon atoms could extend the scope to the visible light region and defect state caused by oxygen vacancy further extended it to infrared region (Figure 3a). Combined with the bandgap structure (Figure S7) and ultraviolet photoelectron spectroscopy (UPS) (Figure S8), a schematic illustration of the bandgap structure of C-In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3-x\u003c/sub\u003e was depicted and shown in Figure S9. The band structure and density of states (DOS) of C-In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3-x\u003c/sub\u003e regulated by doped carbon could be explained using density functional theory (DFT). In Figure S10, compared with the cubic In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, when an oxygen vacancy was generated around an interstitial carbon, a new defect energy level with more massive DOS emerges. In this case, the electrons can be easily excited into the conduction band through the intermediate state, thereby achieving higher photoconversion efficiency\u003csup\u003e45-47\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eOn the other hand, the radiative recombination competed against non-radiative recombination. After carbon doping, the fluorescence significantly quenched, demonstrating that radiative recombination of the photon-generated carriers had been suppressed by extracting the electrons (Figure S11). Therefore, the C-In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3-x\u003c/sub\u003e system could reach near 400 \u0026deg;C within 10 minutes, which is far higher temperature than those of V\u003csub\u003eo\u003c/sub\u003e-poor In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e and V\u003csub\u003eo\u003c/sub\u003e-rich In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u003csub\u003e-x\u003c/sub\u003e (Figure 3b). The surface of C-In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3-x\u003c/sub\u003e worked as a \"nanoscale heat source,\" which absorbed the photon energy and rapidly converted it into heat that was conducted to the active sites of C-In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3-x\u003c/sub\u003e in a short time.\u003c/p\u003e\n\u003cp\u003eThe next step was adsorption of gas molecules onto the surface and subsequent catalytic process. For clarity, in temperature-programmed desorption (TPD) of CO\u003csub\u003e2\u003c/sub\u003e, the peak at 480℃ indicated the adsorption was in the form of chemisorption via the oxygen vacancies on C-In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3-x\u003c/sub\u003e\u003csup\u003e48,49\u003c/sup\u003e.\u0026nbsp; If the oxygen vacancy is filled under annealing in air, the adsorption capacity could be notably reduced (Figure S12). In order to prove the role of oxygen vacancy as the active site was in the catalytic process, we conducted comparative DFT calculations of In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e and In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e-O\u003csub\u003evac\u003c/sub\u003e [110] slabs (Figure S13 -15). The Gibbs free energy for the intermediate *CO of RWGS reaction on In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e slab without oxygen vacancy was 0.66 eV which was higher than the slab with oxygen vacancy (0.32 eV). Thus, a high concentration of oxygen vacancies was expected to increase the capacity of CO\u003csub\u003e2\u003c/sub\u003e adsorption and lower the energy barrier of photothermal CO\u003csub\u003e2\u003c/sub\u003e reduction RWGS reaction. Electron spin resonance spectroscopy (ESR) effectively evaluated the oxygen vacancy concentration (Figure 3c). Limited signals of V\u003csub\u003eo\u003c/sub\u003e-poor In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e and V\u003csub\u003eo\u003c/sub\u003e-rich In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3-x\u003c/sub\u003e were detected, while a stronger signal of C-In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3-x \u003c/sub\u003eappeared at g=2.004, which could be explained as more concentrated electrons are trapped around the surface oxygen vacancies\u003csup\u003e50\u003c/sup\u003e. Next, to prove the carbon doping has a function in elevating oxygen vacancy concentration, the formation energy of oxygen vacancy was simulated (inset of Figure 3c). In non-defective In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e crystal, the oxygen vacancy formation energy was 4.98 eV, while the energy decreased to 3.10 eV after interstitial carbon anchored into In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e lattice (Table S3). Our result suggested that interstitial carbon assembled with oxygen vacancy to form a higher concentration active sites, thereby pushing forward the RWGS reaction.\u003c/p\u003e\n\u003cp\u003eWe then performed the in-situ Fourier Transform Infrared (FTIR) characterization in a flow cell to investigate the catalytic pathway of RWGS reaction on the active sites of C-In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3-x\u003c/sub\u003e. As displayed in Figure 3d, the C-In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3-x\u003c/sub\u003e exhibited OH stretching band within the range 3400-3730 cm\u003csup\u003e-1\u003c/sup\u003e. Peaks located at 1500 and 1390 cm\u003csup\u003e\u0026minus;1\u003c/sup\u003e were identified as chemisorbed CO\u003csub\u003e2\u003c/sub\u003e and H\u003csub\u003e2 \u003c/sub\u003emolecules, as well as bicarbonate (HCO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e) and carbonate (CO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u0026minus;\u003c/sup\u003e) formation. The detectable peak at 2894 cm\u003csup\u003e\u0026minus;1\u003c/sup\u003e was attributed to bending vibration \u0026delta;(CH). Here, the peaks corresponding to crucial intermediate methoxy (H\u003csub\u003e3\u003c/sub\u003eCO*) in the spectra were at 2839 and 1090 cm\u003csup\u003e\u0026minus;1\u003c/sup\u003e, and COOH* were at 1578 and 1232 cm\u003csup\u003e\u0026minus;1\u003c/sup\u003e. Therefore, the incoming electrons coupled with resident protons reduced the amount of CO\u003csub\u003e2\u003c/sub\u003e molecules at the active sites, oxygen vacancy, then formed COOH* and H\u003csub\u003e3\u003c/sub\u003eCO* intermediates and transferred into CO* consistently. Simultaneously, the peak at 2107 cm\u003csup\u003e\u0026minus;1\u003c/sup\u003e and 1643 cm\u003csup\u003e\u0026minus;1 \u003c/sup\u003ewere the diagnostic vibrational modes of CO and H\u003csub\u003e2\u003c/sub\u003eO respectively, indicating the reaction pathway that features CO* as the intermediate from carboxyl through the RWGS reaction\u003csup\u003e51-54\u003c/sup\u003e. In general, oxygen vacancy with doped carbon as active sites effectively activated CO\u003csub\u003e2\u003c/sub\u003e molecules and stabilized the intermediates, so as to reduce the activation energy and promote photothermal CO\u003csub\u003e2\u003c/sub\u003e reduction (Figure 3e).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eIn summary, photothermal catalytic CO\u003csub\u003e2\u003c/sub\u003e reduction is a promising technology to alter the traditional thermo-catalytic reaction, which thermodynamically improves activity under light conditions without additional energy input. The dual-function carbon doping is a feasible option to enhance and stabilize photothermal catalyst activity of In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e. Doped carbon is more conducive to the light absorption and the photothermal conversion efficiency improvement; benefiting from formation energy reduction of oxygen vacancy, high concentration active sites are obtainable. As a result, the C-In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3-x\u003c/sub\u003e has 123.6 mmol g\u003csup\u003e-1\u003c/sup\u003e h\u003csup\u003e-1\u003c/sup\u003e of CO production rates and nearly 100% selectivity. This work demonstrates that the microstructure modulation of crystal defect in catalyst can significantly enhanced the utilization of solar light and then to drive efficient and stable catalytic reaction, which achieves high-performance solar-to-chemical energy conversion.\u003c/p\u003e"},{"header":"Experimental Section","content":"\u003cp\u003e\u003cem\u003eMaterials\u003c/em\u003e: Synthesis of V\u003csub\u003eo\u003c/sub\u003e-poor In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3 \u003c/sub\u003eand V\u003csub\u003eo\u003c/sub\u003e-rich In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3-x\u003c/sub\u003e nano partials: First, 1 mmol indium nitrate was added into 60 mL deionized water, magnetically stirred for 20 min, then mixed with 3 mmol urea followed by another 10 min stirring. After, the mixture was transferred into a 100 mL Teflon-lined stainless-steel autoclave, sealed and maintained at 140\u0026deg;C for 12 hours. The whole system naturally cools down to room temperature. After centrifuging the mixture, the final product was collected, washed with distilled water and ethanol several times and then dried in air at 60℃. Calcination is at 600 \u0026deg;C for 2 h in air and H\u003csub\u003e2\u003c/sub\u003e-Ar with a heating rate of 5 \u0026deg;C min\u003csup\u003e\u0026minus;1\u003c/sup\u003e to fabricate the V\u003csub\u003eo\u003c/sub\u003e-poor In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e and V\u003csub\u003eo\u003c/sub\u003e-rich In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3-x\u003c/sub\u003e. The synthesis procedure for C-In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e is similar to that of V\u003csub\u003eo\u003c/sub\u003e-poor In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3 \u003c/sub\u003eand V\u003csub\u003eo\u003c/sub\u003e-rich In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3-x\u003c/sub\u003e, except that 1 mmol of indium nitrate, 3 mmol urea and different amounts of glucose (0.1, 0.2, 0.3, 0.4, and 0.5 g) were simultaneously added into the starting solution for hydrothermal synthesis, and calcination at 600 \u0026deg;C for 2 h in Ar.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eReaction condition and activity evaluation: \u003c/em\u003ePhotothermal CO\u003csub\u003e2\u003c/sub\u003e conversion by H\u003csub\u003e2\u003c/sub\u003e was carried out in a batch type reaction system with a total volume of 330 ml. After evacuation of reaction system, CO\u003csub\u003e2\u003c/sub\u003e and H\u003csub\u003e2\u003c/sub\u003e (the molar ratio of H\u003csub\u003e2\u003c/sub\u003e to CO\u003csub\u003e2\u003c/sub\u003e is 1:1) were injected. A 300W Xe lamp was used as irradiation source to drive the photothermal CO\u003csub\u003e2\u003c/sub\u003e conversion. The light intensity is 2.98 W cm\u003csup\u003e-2\u003c/sup\u003e. The temperature of catalyst surface is measured by the infrared thermometer, and the reflectance coefficient is 0.78. For all experiments, 0.05 g of sample was used and spread onto a round shape air-permeable quartz fiber filter with the area of 7 cm\u003csup\u003e2\u003c/sup\u003e. The quartz fiber filter film is fixed on the stage inside the reactor. The tip of thermometer was maintained an intimate contact with the sample (thickness of catalyst powder is about 1~2 mm). The contents of CO\u003csub\u003e2\u003c/sub\u003e and CO in the reaction system were sampled and measured with a gas chromatograph (GC-2014, Shimadzu) equipped with a methanizer and flame ionization detector according to the standard curves.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eSample characterization: \u003c/em\u003eXRD patterns were recorded on an X-Pert diffractometer equipped with graphite monochromatized Cu-K radiation. The morphologies were characterized by field-emission SEM (Hitachi, s4800) and TEM (JEOL, 2100F). The diffuse reflection spectra of catalysts were measured by UV\u0026ndash;vis-NIR spectrophotometer (Shimadzu, UV-3600) from 220 to 2400 nm. Chemical valence of the surface was analyzed by XPS (Escalab 250Xi, Thermo Scientific, America). The PL properties of materials were investigated by PL spectra (Horiba Fluorolog-3) with the excitation light wavelength of 350 nm. The ESR spectra measurements were executed on JES-FA200 X-band spectrometer. The catalyst temperature was probed by a digital thermometer (Custom, CT-1200D). Raman spectra were recorded by Horiba (Xplora Plus) instrument. The pore size distribution was determined with a surface area analyzer (BEL Sorp-II mini, BEL Japan Co., Japan) by the BET method. The FTIR spectrum was executed on Nicolet 6700. In situ FTIR spectra have been recorded by a Nicolet 6700 Fourier transform instrument, using conventional IR cells connected to a gas manipulation apparatus. XAS measurement for the In K-edge was performed in fluorescence mode on beamline 20-BM-B with electron energy of 7 GeV and an average current of 100 mA which is located in the Advanced Photon Source at Argonne National Laboratory.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eAcknowledgements\u0026nbsp;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThis work received financial support from the National Natural Science Foundation of China (Grants 21972052 and 21633004) and JSPS KAKENHI of Japan (Grant Number JP18H02065).\u003c/p\u003e"},{"header":"References","content":"\n\u003col\u003e\n\u003cli\u003eWalter, M.G. et al. Solar Water Splitting Cells. \u003cem\u003eChem Rev\u003c/em\u003e \u003cstrong\u003e110\u003c/strong\u003e, 6446-6473 (2010).\u003c/li\u003e\n\u003cli\u003eChu, S. \u0026amp; Majumdar, A. 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Catalytic behavior of metal catalysts in high-temperature RWGS reaction: In-situ FT-IR experiments and first-principles calculations. \u003cem\u003eSci Rep\u003c/em\u003e \u003cstrong\u003e7\u003c/strong\u003e, 41207 (2017).\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Scheme","content":"\u003cp\u003eScheme 1 is available in the Supplementary Files.\u003c/p\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":"indium oxide, carbon doping, oxygen vacancy, photothermal catalysis, CO2 reduction","lastPublishedDoi":"10.21203/rs.3.rs-102590/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-102590/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003ePhotothermocatalytic CO\u003csub\u003e2\u003c/sub\u003e reduction as the channel of the energy and environmental issues resolution has captured persistent attention in recent years. In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e has been prompted to be a potential photothermal catalyst in this sector on account of unique physicochemical properties. However, different from the metal-based photothermal catalyst with the nature of efficient light-to-thermal conversion and H\u003csub\u003e2\u003c/sub\u003e dissociation, the wide-bandgap semiconductor needs to be modified to possess wide-wavelength-range absorption and the active surface. It remains a challenge to achieve the two aims simultaneously via single material modulation approach. In this study, one strategy of carbon doping can empower In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e with two advantageous modifications. The carbon doping can reduce the formation energy of oxygen vacancy, which induces the generation of oxygen-vacancy-riched material. The introduction of oxygen defect levels and carbon doping levels in band gap of In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e significantly reduces this band gap, which endows it full-spectral and intensive solar light absorption. Therefore, the carbon doped In\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e achieves effective light-to-thermal conversion and delivers a 123.6\u0026nbsp;mmol g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e h\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e of CO generation rate with near-unity selectivity, as well as prominent stability in photothermocatalytic CO\u003csub\u003e2\u003c/sub\u003e reduction.\u003c/p\u003e","manuscriptTitle":"Fabrication of Black In2O3 with Dense Oxygen Vacancy through Dual Functional Carbon Doping for Enhancing Photothermal CO2 Hydrogenation","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2020-11-09 16:55:13","doi":"10.21203/rs.3.rs-102590/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":"2ce987e9-c951-47d6-a5b1-4c49e4aa71d0","owner":[],"postedDate":"November 9th, 2020","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":1008531,"name":"Catalysis"},{"id":1008532,"name":"Energy Engineering"}],"tags":[],"updatedAt":"2020-12-08T16:25:50+00:00","versionOfRecord":[],"versionCreatedAt":"2020-11-09 16:55:13","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-102590","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-102590","identity":"rs-102590","version":["v1"]},"buildId":"WrCJVZZCHTDjtuVLN7oU0","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}