Metal to non-metal sites of metallic sulfides switching products from CO to CH for photocatalytic CO reduction.

The active center for the adsorption and activation of carbon dioxide plays a vital role in the conversion and product selectivity of photocatalytic CO reduction. Here, we find multiple metal sulfides CuInSnS octahedral nanocrystal with exposed (1 1 1) plane for the selectively photocatalytic CO reduction to methane. Still, the product is switched to carbon monoxide on the corresponding individual metal sulfides InS, SnS, and CuS. Unlike the common metal or defects as active sites, the non-metal sulfur atom in CuInSnS is revealed to be the adsorption center for responding to the selectivity of CH products. The carbon atom of CO adsorbed on the electron-poor sulfur atom of CuInSnS is favorable for stabilizing the intermediates and thus promotes the conversion of CO to CH. Both the activity and selectivity of CH products over the pristine CuInSnS nanocrystal can be further improved by the modification of with various co-catalysts to enhance the separation of the photogenerated charge carrier. This work provides a non-metal active site to determine the conversion and selectivity of photocatalytic CO reduction.