Mg-doped SrTiO3 Photocatalyst with Ag-Co Cocatalyst for Enhanced Selective Conversion of CO2 to CO Using H2O as the Electron Donor

28 February 2023, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

Photocatalytic conversion of CO2 by H2O is a promising method for solving energy and environmental problems. In this context, efficient photocatalysts that facilitate the selective conversion of CO2 to the value-added chemical CO are essential. In this study, for the first time in the literature, we used an Mg-doped SrTiO3 photocatalyst (Mg-SrTiO3) for the photocatalytic conversion of CO2 to CO using H2O as the electron donor under monochromatic UV-light irradiation at 365 nm. Compared to pristine SrTiO3, Mg-SrTiO3, which is prepared via a flux method, exhibited dramatically enhanced conversion of CO2 to CO in the presence of Ag-Co cocatalyst. Moreover, the selectivity toward CO evolution was greater than 99%, indicating suppression of the unnecessary and competitive H2 evolution. Scanning electron microscopy of Mg-SrTiO3 revealed edge-shaved cubic particles, which were correlated to the anisotropic distribution of photogenerated electrons and holes and the consequent enhancement of photocatalytic activity. Furthermore, the Mg-doping temperature and amount used to prepare Mg-SrTiO3 influenced the substitution of Ti4+ sites in the bulk of SrTiO3 by Mg2+, thereby affecting the CO evolution. The apparent quantum efficiency of optimal Mg-SrTiO3 in the photocatalytic conversion of CO2 was determined to be 0.05%.

Keywords

CO2 photoreduction
Perovskite oxides
Mg2+-doping
Edges-shaved cubes

Supplementary materials

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Supporting Information
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XRD patterns and UV-Vis spectra of M−SrTiO3, Reaction results for photocatalytic conversion of CO2 over Ag−Co/Mg−ATiO3 (A = Ba, Ca, and Sr), Ag K-edge XANES spectra of Ag−Co/Mg−SrTiO3, TEM image of Mg−SrTiO3 whose cocatalysts were loaded by PD method, Reaction results for photocatalytic conversion of CO2 over Mg−SrTiO3 in the presence of Ag−Co cocatalysts loaded by PD, IMP, and CR method, Particle diameter distributions of Ag loaded by PD, IMP, and CR method, Reaction results for photocatalytic conversion of CO2 over Ag−Co/MgO/SrTiO3, Ag−Co/MgO/Al−SrTiO3, Ag−Co/Al−SrTiO3 and Ag−Co/Mg−SrTiO3, A SEM image of Mg−SrTiO3_1118 K, XRD patterns of Mg−SrTiO3_y h, Reaction results for photocatalytic conversion of CO2 over Ag−Co/Mg−SrTiO3_y h, XRD patterns of Mg(z)−SrTiO3, Blank tests for Ag−Co/Mg−SrTiO3, A time-course reaction result for photocatalytic conversion of CO2 over the Ag−Co/Mg−SrTiO3 for 15 h, The scheme of the reaction vessel and the light source, The calculation of AQE.
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