Oxygen vacancies induced special CO2 adsorption modes on Bi2MoO6 for highly selective conversion to CH4

Abstract Search for suitable photocatalysts with ultrahigh selective generation of CH4 from CO2 is a great challenge in artificial photocatalysis. Herein, effective CO2 photoconversion to CH4 with high selectivity up to 96.7% is achieved over oxygen-deficient Bi2MoO6 under visible-light. Various characterizations and DFT calculations indicated that well-designed oxygen vacancies (OVs) on the {001} surface of Bi2MoO6 can not only enhance light harvesting and e−-/h+ separation, but favor CO2 adsorption in a special bidentate carbonate mode, which thermodynamically supports the further hydrogenation of intermediate *CO to generate CH4. Based on the in-situ infrared spectroscopy analysis, the CO2 adsorption modes and reaction intermediates of two pathways over Bi2MoO6 with or without OVs were figured out. The reasonable photocatalytic mechanism for highly selective conversion to CH4 was also proposed. This work provides new insights to the role of OVs in selective CO2 photoconversion, and paves ways to design efficient CH4 evolution systems.

[1]  Y. Xiong,et al.  Defect engineering in photocatalytic materials , 2018, Nano Energy.

[2]  T. Peng,et al.  Pt-loading reverses the photocatalytic activity order of anatase TiO2 {0 0 1} and {0 1 0} facets for photoreduction of CO2 to CH4 , 2014 .

[3]  Jinhua Ye,et al.  In Situ Carbon Homogeneous Doping on Ultrathin Bismuth Molybdate: A Dual‐Purpose Strategy for Efficient Molecular Oxygen Activation , 2017 .

[4]  Qinghong Zhang,et al.  MgO- and Pt-Promoted TiO2 as an Efficient Photocatalyst for the Preferential Reduction of Carbon Dioxide in the Presence of Water , 2014 .

[5]  Qinghong Zhang,et al.  Photocatalytic and photoelectrocatalytic reduction of CO2 using heterogeneous catalysts with controlled nanostructures. , 2016, Chemical communications.

[6]  Zhen Wei,et al.  Controlled synthesis of a highly dispersed BiPO4 photocatalyst with surface oxygen vacancies. , 2015, Nanoscale.

[7]  John-Paul Jones,et al.  Recycling of carbon dioxide to methanol and derived products - closing the loop. , 2014, Chemical Society reviews.

[8]  Qiang Ma,et al.  Ultrathin W18O49 nanowires with diameters below 1 nm: synthesis, near-infrared absorption, photoluminescence, and photochemical reduction of carbon dioxide. , 2012, Angewandte Chemie.

[9]  Maor F. Baruch,et al.  Light-Driven Heterogeneous Reduction of Carbon Dioxide: Photocatalysts and Photoelectrodes. , 2015, Chemical reviews.

[10]  Yuxin Zhang,et al.  Defective Bi4MoO9/Bi metal core/shell heterostructure: Enhanced visible light photocatalysis and reaction mechanism , 2018, Applied Catalysis B: Environmental.

[11]  J. Shang,et al.  Oxygen Vacancy Associated Surface Fenton Chemistry: Surface Structure Dependent Hydroxyl Radicals Generation and Substrate Dependent Reactivity. , 2017, Environmental science & technology.

[12]  Hao Chen,et al.  Novel in situ fabrication of conjugated microporous poly(benzothiadiazole)–Bi2MoO6 Z-scheme heterojunction with enhanced visible light photocatalytic activity , 2017 .

[13]  T. Chen,et al.  Surface Phases of TiO2 Nanoparticles Studied by UV Raman Spectroscopy and FT-IR Spectroscopy , 2008 .

[14]  Yi Xie,et al.  Infrared Light-Driven CO2 Overall Splitting at Room Temperature , 2018 .

[15]  Bo Li,et al.  Enhanced photocatalytic performance of ordered mesoporous Fe-doped CeO2 catalysts for the reduction of CO2 with H2O under simulated solar irradiation , 2014 .

[16]  Licheng Sun,et al.  Simultaneously efficient light absorption and charge transport of phosphate and oxygen-vacancy confined in bismuth tungstate atomic layers triggering robust solar CO2 reduction , 2017 .

[17]  A. Asthagiri,et al.  Selectivity of CO(2) reduction on copper electrodes: the role of the kinetics of elementary steps. , 2013, Angewandte Chemie.

[18]  Lianjun Liu,et al.  Photocatalytic CO2 Reduction with H2O on TiO2 Nanocrystals: Comparison of Anatase, Rutile, and Brookite Polymorphs and Exploration of Surface Chemistry , 2012 .

[19]  Haiquan Xie,et al.  Oxygen vacancies induced exciton dissociation of flexible BiOCl nanosheets for effective photocatalytic CO2 conversion , 2017 .

[20]  Jacek K. Stolarczyk,et al.  Photocatalytic reduction of CO2 on TiO2 and other semiconductors. , 2013, Angewandte Chemie.

[21]  J. Shang,et al.  Efficient Visible Light Nitrogen Fixation with BiOBr Nanosheets of Oxygen Vacancies on the Exposed {001} Facets. , 2015, Journal of the American Chemical Society.

[22]  N. Zhang,et al.  Nanochemistry-derived Bi2WO6 nanostructures: towards production of sustainable chemicals and fuels induced by visible light. , 2014, Chemical Society reviews.

[23]  M. Guzman,et al.  Cu 2 O/TiO 2 heterostructures for CO 2 reduction through a direct Z-scheme: Protecting Cu 2 O from photocorrosion , 2017 .

[24]  B. Pan,et al.  Oxygen-Vacancy-Mediated Exciton Dissociation in BiOBr for Boosting Charge-Carrier-Involved Molecular Oxygen Activation. , 2018, Journal of the American Chemical Society.

[25]  A. Mohamed,et al.  Oxygen vacancy induced Bi2WO6 for the realization of photocatalytic CO2 reduction over the full solar spectrum: from the UV to the NIR region. , 2016, Chemical communications.

[26]  K. Zhao,et al.  Surface structure-dependent molecular oxygen activation of BiOCl single-crystalline nanosheets. , 2013, Journal of the American Chemical Society.

[27]  Sen Xin,et al.  Photocatalytic CO2 reduction highly enhanced by oxygen vacancies on Pt-nanoparticle-dispersed gallium oxide , 2016, Nano Research.

[28]  Jinlong Gong,et al.  CO2 photo-reduction: insights into CO2 activation and reaction on surfaces of photocatalysts , 2016 .

[29]  Shanshan Liu,et al.  A rapidly room-temperature-synthesized Cd/ZnS:Cu nanocrystal photocatalyst for highly efficient solar-light-powered CO2 reduction , 2018, Applied Catalysis B: Environmental.

[30]  Jinhua Ye,et al.  Light‐Switchable Oxygen Vacancies in Ultrafine Bi5O7Br Nanotubes for Boosting Solar‐Driven Nitrogen Fixation in Pure Water , 2017, Advanced materials.

[31]  Dan Chen,et al.  Facet-Dependent Photocatalytic N2 Fixation of Bismuth-Rich Bi5O7I Nanosheets. , 2016, ACS applied materials & interfaces.

[32]  Weiqiang Wu,et al.  Photoinduced reactions of surface-bound species on titania nanotubes and platinized titania nanotubes: An in situ FTIR study , 2013 .

[33]  Yi Luo,et al.  New Mechanism for Photocatalytic Reduction of CO2 on the Anatase TiO2(101) Surface: The Essential Role of Oxygen Vacancy. , 2016, Journal of the American Chemical Society.

[34]  Caijin Huang,et al.  Boron Carbon Nitride Semiconductors Decorated with CdS Nanoparticles for Photocatalytic Reduction of CO2 , 2018 .

[35]  Yi Xie,et al.  Efficient Visible-Light-Driven CO2 Reduction Mediated by Defect-Engineered BiOBr Atomic Layers. , 2018, Angewandte Chemie.

[36]  Jinlong Zhang,et al.  Modulation of the Reduction Potential of TiO2- x by Fluorination for Efficient and Selective CH4 Generation from CO2 Photoreduction. , 2018, Nano letters.

[37]  N. Lewis,et al.  Powering the planet: Chemical challenges in solar energy utilization , 2006, Proceedings of the National Academy of Sciences.

[38]  Yong Zhou,et al.  Photocatalytic Conversion of CO2 into Renewable Hydrocarbon Fuels: State‐of‐the‐Art Accomplishment, Challenges, and Prospects , 2014, Advanced materials.

[39]  T. Peng,et al.  Increasing visible-light absorption for photocatalysis with black BiOCl. , 2012, Physical chemistry chemical physics : PCCP.

[40]  Falong Jia,et al.  Oxygen Vacancy-Mediated Photocatalysis of BiOCl: Reactivity, Selectivity, and Perspectives. , 2018, Angewandte Chemie.

[41]  T. Peng,et al.  Recent Advances in Heterogeneous Photocatalytic CO2 Conversion to Solar Fuels , 2016 .

[42]  Ying Li,et al.  Engineering Coexposed {001} and {101} Facets in Oxygen-Deficient TiO2 Nanocrystals for Enhanced CO2 Photoreduction under Visible Light , 2016 .

[43]  Cheng Lian,et al.  Atomically-thin Bi2MoO6 nanosheets with vacancy pairs for improved photocatalytic CO2 reduction , 2019, Nano Energy.

[44]  Annick Rubbens,et al.  A Comprehensive Scenario of the Crystal Growth of γ-Bi2MoO6 Catalyst during Hydrothermal Synthesis , 2012 .

[45]  Junseok Lee,et al.  Electron-induced dissociation of CO2 on TiO2(110). , 2011, Journal of the American Chemical Society.

[46]  C. Dong,et al.  Size-dependent activity and selectivity of carbon dioxide photocatalytic reduction over platinum nanoparticles , 2018, Nature Communications.

[47]  Yunlin Liu,et al.  Crystal Defect Engineering of Aurivillius Bi2MoO6 by Ce Doping for Increased Reactive Species Production in Photocatalysis , 2016 .

[48]  M. Head‐Gordon,et al.  Quantum Mechanical Screening of Single-Atom Bimetallic Alloys for the Selective Reduction of CO2 to C1 Hydrocarbons , 2016 .

[49]  Wei Chen,et al.  Concave Bi2WO6 nanoplates with oxygen vacancies achieving enhanced electrocatalytic oxygen evolution in near-neutral water , 2016 .

[50]  X. Tao,et al.  Synthesis and characterization of g-C3N4/Bi2MoO6 heterojunctions with enhanced visible light photocatalytic activity , 2014 .

[51]  Changpeng Liu,et al.  An effective Pd-Ni(2)P/C anode catalyst for direct formic acid fuel cells. , 2014, Angewandte Chemie.

[52]  Hao Chen,et al.  Oxygen vacancy boosted photocatalytic decomposition of ciprofloxacin over Bi2MoO6: Oxygen vacancy engineering, biotoxicity evaluation and mechanism study. , 2019, Journal of hazardous materials.

[53]  G. Spoto,et al.  CO2 Capture by TiO2 Anatase Surfaces: A Combined DFT and FTIR Study , 2014 .