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

A selective CO evolution from photoreduction of CO 2 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 CO 2 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 H 2 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.