Abstract

The photocatalytic carbon dioxide (CO2) reduction is a very promising approach for harvesting solar energy and recycling carbon resources. However, the native defects induced competition among different pathways for photocarriers is inevitable and negatively affects the selectivity. This work studies the competition between the vacancy induced pathway and the normal in a molybdenum sulfide selenide during photocatalytic CO2 reduction. It has been revealed that the high concentration of chalcogen vacancies can open up the carbene pathway by lowering the free energy and adjusting the adsorptions for the critical intermediates of *CH2 to attract the neighboring *CO for the C-C coupling in the ethanol production, and therefore improve the ethanol production obviously. We propose that in the design of photocatalysts for C2+ production, construction of variant active sites for the coupling of matching intermediates should be fully considered when choosing the basic materials, dopants and native defects.