1. Department of Chemical Engineering and Catalysis for Renewable Fuels (CReF) Center, University of South Carolina, Columbia, SC 29208, USA 2. Department of Metallurgical and Chemical Engineering, Jiyuan Vocational and Technical Collage, Jiyuan 459000, China 3. State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
Ti3+-doped TiO2 nanosheets with tunable phase composition (doped TiO2 (A/R)) were synthesized via a hydrothermal method with high surface area anatase TiO2 nanosheets TiO2 (A) as a substrate, structure directing agent, and inhibitor; the activity was evaluated using a probe reaction-photocatalytic CO2 conversion to methane under visible light irradiation with H2 as an electron donor and hydrogen source. High-resolution transmission electron microscope (HRTEM), field emission scanning electron microscope, UV-Vis diffuse reflectance spectra, and X-ray diffraction (XRD) etc., were used to characterize the photocatalysts. XRD and HRTEM measurements confirmed the existence of anatase-rutile phase junction, while Ti3+ and single-electron-trapped oxygen vacancy in the doped TiO2 (A/R) photocatalyst were revealed byelectron paramagnetic resonance (EPR) measurements. Effects of hydrothermal synthesis temperature and the amount of added anatase TiO2 on the photocatalytic activity were elucidated. Significantly enhanced photocatalytic activity of doped TiO2 (A/R) was observed; under the optimized synthesis conditions, CH4 generation rate of doped TiO2 (A/R) was 2.3 times that of Ti3+-doped rutile TiO2.
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