Site-Selective Deposition of Reductive and Oxidative Dual Cocatalysts To Improve the Photocatalytic Hydrogen Production Activity of CaIn2S4 with a Surface Nanostep Structure.

Abstract

Photocatalytic hydrogen production from water exhibits great potential for solar energy conversion. In this work, using monoclinic CaIn2S4 with a surface nanostep structure as a model photocatalyst, we demonstrate a facile and efficient strategy for the construction of AO x/AuCu/CaIn2S4 (A = Mn, Ni, and Pb) composites by site-selective photodeposition of the reductive cocatalyst AuCu alloy and oxidative cocatalyst AO x on the edge and groove sites of CaIn2S4 nanosteps, respectively. Compared to single-cocatalyst composites (AuCu/CaIn2S4 and AO x/CaIn2S4) and CaIn2S4, the simultaneous deposition of AuCu and AO x spatially separate the photogenerated charges and the photocatalytic reaction sites, therefore effectively improving the separation efficiency of charge carriers. Meanwhile, the synergistic effect of AuCu and AO x dual cocatalysts notably reduces the apparent activation energy for the photocatalytic hydrogen production reaction. These novel dual-cocatalyst composites show enhanced performance for hydrogen production under visible light irradiation. A high rate of hydrogen production of 95.75 mmol h-1 g-1 is achieved over the MnO x/AuCu/CaIn2S4 composite with the deposition of 0.5 wt % AuCu and 0.2 wt % MnO x. Our work sheds new lights on designing efficient photocatalytic materials with site-selective surface deposition of reductive and oxidative dual cocatalysts for solar energy conversion.