Dependence of Exposed Facet of Pd on Photocatalytic H2-Production Activity

Structure-sensitive activity of metal cocatalysts in photocatalysis has been one of the most important topics in recent years. Herein, we construct a model photocatalytic system of shape-controlled Pd/TiO 2 hybrids to investigate the effect of surface atomic structure of Pd cocatalysts in the photocatalytic H 2 evolution reaction. Cubic- and tetrahedral-Pd nanocrystals are respectively in situ deposited on the surface of cubic-anatase-TiO 2, establishing strong interface contact between the two indispensable components in the photocatalytic H 2 evolution reaction: photocatalyst (TiO 2 ) and cocatalyst (Pd). Experimental results and theoretical calculations based on this Pd/TiO 2 model system demonstrate that the cocatalytic performance of Pd(111) facets is more effective than that of Pd(100) facets in various reaction solutions. This is due to the more efficient capture of photogenerated electrons from the conduction band of TiO 2, as well as the more preferable adsorption of H, transformation of H into the H 2 molecule, and desorption of the H 2 molecule in the HER process of the Pd(111) surface.