Sunlight induced photo-thermal synergistic catalytic CO2 conversion via localized surface plasmon resonance of MoO3−x

Photocatalytic conversion of CO2 to solar fuels is considered an alternative approach for simultaneously mitigating the greenhouse effect and solving energy shortage. The efficient light harvesting and the thermochemical conversion have been demanding quests in photocatalysis due to the relatively low solar energy utilization efficiency. In this work, oxygen vacancies are induced in MoO3 for improving photo-thermal CO2 reduction efficiency by capturing near-infrared (NIR) photons. The localized surface plasmon resonance (LSPR) of MoO3−x triggered by oxygen vacancies enables the efficient capture of NIR photons. Additionally, oxygen vacancies can promote the carrier separation, improve CO2 adsorption on the defective surface and lower the barrier of CO2 hydrogenation during the conversion process. As a result, MoO3−x displayed dramatically enhanced photo-thermal synergistic CO2 reduction under simulated sunlight (UV-Vis-IR) irradiation than MoO3. The amount of CO produced by MoO3−x can reach 10.3 μmol g−1 h−1, which is 20 times higher than that of MoO3 (0.52 μmol g−1 h−1). And the CH4 production of MoO3−x can reach 2.08 μmol g−1 h−1, which is 52 times higher than that of MoO3 (0.04 μmol g−1 h−1). In situ FT-IR and theoretical calculations also proved the enhanced activity of MoO3−x. This work highlights the significance of defect engineering for improving the photo-thermal catalytic conversion of CO2.