Operando DRIFTS-MS investigation on plasmon-thermal coupling mechanism of CO2 hydrogenation on Au/TiO2: The enhanced generation of oxygen vacancies

Using solar energy to promote the thermocatalytic CO2 conversion is a promising way to reduce the energy consumption and increase the sustainability. Au/TiO2 is known for its good catalytic activity in both thermo- and photo- catalytic CO2 conversion, however both the reaction mechanisms in dark and in photo-thermo coupled reaction condition remain unclear. In this work, the operando isotope-labelled spectroscopic and computational analyses are combined to clarify these mechanisms. The redox mechanism that CO2 direct dissociation at the oxygen vacancy (VO) is found as the main reaction pathway of CO2 hydrogenation over Au/TiO2. The plasmonic enhancement mechanism is proven to be the hot electrons facilitated VO generation at interface. The clear understandings of reaction pathway and plasmonic enhancement mechanism are helpful for the future design of photo-thermal CO2 conversion catalysts.