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

Abstract

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 MoO_3−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, MoO_3−x displayed dramatically enhanced photo-thermal synergistic CO₂ reduction under simulated sunlight (UV-Vis-IR) irradiation than MoO₃. The amount of CO produced by MoO_3−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 MoO_3−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 MoO_3−x. This work highlights the significance of defect engineering for improving the photo-thermal catalytic conversion of CO₂.