Engineering on the edge of Pd nanosheet cocatalysts for enhanced photocatalytic reduction of CO2 to fuels

The utilization of a metal cocatalyst is a promising route to improve the solar-to-chemical conversion efficiency of semiconductor-based photocatalysts. The efficiency of the improvement is greatly dependent on the architectural structure of the metal cocatalysts, especially the catalytically active sites on the surface of the cocatalysts. In this article, Pd nanosheets with different sizes have been hybridized with TiO2 nanosheets to disclose how the edge of Pd cocatalysts influences the photocatalytic performance of TiO2-Pd hybrid structures in the reduction of CO2 to fuels. It was found that the highest photocatalytic activity was realized by small Pd nanosheets with the highest edge density on the TiO2 nanosheets. The reason is that the edges of the nanosheets act as the highly active sites for the CO2 reduction reaction. To further verify the edge-dependent photocatalytic performance, Pd nanorings were also deposited on the TiO2 nanosheets, which further improve the photocatalytic activity as compared with original nanosheets resulting from the additional edge sites exposed on the side of the hollow interior in the rings. This work underlines the importance in the edge engineering on the surface of cocatalysts in realizing high-performance photocatalytic applications.