Thermal coupled photoconductivity as a tool to understand the photothermal catalytic reduction of CO2

Abstract

Photocatalysis shows great promise in the field of solar energy conversion. One of the reasons for this is because it promotes the development of multi-field-coupled catalysis. In order to explore the principles of multi-field-coupled catalytic reactions, an in situ multi-field-coupled characterization technique is required. In this study, we obtained hydrogenated ST-01 TiO2 and observed enhanced catalytic activity by thermal coupled photocatalysis. In situ photoconductivity was employed to understand the activity enhancement. The effects of the reaction temperature, reaction atmosphere, and oxygen vacancy (Ov) on the photoconductivity of TiO2 were studied. After coupling thermal into photoconductivity measurement, highly active Ov-TiO2 displayed rapid decay of photoconductivity in a CO2 atmosphere and slow decay of photoconductivity in a N2 atmosphere. These phenomena revealed that photothermal coupling assisted the detrapping of electrons at the Ov surface and promoted electron transfer to CO2, which clearly explained the high photothermal catalytic activity of Ov-TiO2. This study demonstrated that photoconductivity is a useful tool to help understand photothermal catalytic phenomena.