Grain boundary engineered metal nanowire cocatalysts for enhanced photocatalytic reduction of carbon dioxide

Abstract The combination of metal cocatalysts with light-harvesting semiconductors is a promising route to improving the photocatalytic performance in CO 2 reduction reaction. However, owing to the high H 2 O activation ability of metal surface, the H 2 evolution from water as a side reaction greatly decreases the activity and selectivity for CO 2 reduction. Herein, we demonstrate that the photocatalytic performance in CO 2 reduction can be promoted by grain boundaries (GBs) on metal cocatalysts. In this work, metal (Rh and Pd) nanowires with high density of GB were loaded on TiO 2 nanosheets, which acting as cocatalysts effectively reduce the H 2 evolution and greatly enhance the photocatalytic performance in CO 2 reduction as compared with the corresponding metal nanoparticle cocatalysts without GBs. Two effects are believed to contribute to this enhancement: (1) nanowire structure facilitates the interfacial electron transfer from TiO 2 to metal cocatalysts; (2) the GB terminations on the surface of metal cocatalysts are catalytically active sites for CO 2 reduction reaction. This work highlights the rational architectural design of cocatalyst for enhanced photocatalytic performance.