Selective CO Evolution from Photoreduction of CO2 on a Metal-Carbide-Based Composite Catalyst

A selective CO evolution from photoreduction of CO2 in water was achieved on a noble-metal-free, carbide-based composite catalyst, as demonstrated by a CO selectivity of 98.3% among all carbon-containing products and a CO evolution rate of 29.2 μmol h–1, showing superiority to noble-metal-based catalyst. A rapid separation of the photogenerated electron–hole pairs and improved CO2 adsorption on the surface of the carbide component are responsible for the excellent performance of the catalyst. The high CO selectivity is accompanied by a predominant H2 evolution, which is believed to provide a proton-deficient environment around the catalyst to favor the formation of hydrogen-deficient carbon products. The present work provides general insights into the design of a catalyst with a high product selectivity and also the carbon evolution chemistry during a photocatalytic reaction.