Improved charge carrier separation of Schottky junction containing a bimetallic Cu-Pd alloy and N-Bi2WO6 square-shaped discs for photocatalytic H2 performance

Abstract

Bimetallic alloy nanospheres hybridized with semiconductor square-shaped discs are promising catalysts for photocatalytic water splitting, because they exhibit multicomponent interactions, high catalytic activity, and stability. Herein, Cu-Pd/N-Bi2WO6 heterostructures consisting of bimetallic Cu-Pd alloy nanospheres uniformly dispersed on N-Bi2WO6 square-shaped discs are reported. The as-prepared 1 wt% Cu-Pd/N-Bi2WO6 catalyst exhibits a higher H2 production rate (4213 µmol/g) under simulated solar light illumination than N-Bi2WO6 (291 µmol/g). The considerably high H2 production rate is ascribed to the exposed catalytically active sites of the Cu-Pd alloy nanospheres, which facilitate the formation of rapid charge transfer channels between Cu-Pd and N-Bi2WO6. Moreover, the photocatalyst stability is improved by aggregation of the highly dispersed Cu-Pd alloy nanospheres on the N-Bi2WO6 surface. Accordingly, a reaction mechanism based on the work functions of the bimetallic Cu-Pd alloy nanospheres and N-Bi2WO6 square-shaped discs is proposed to elucidate the photocatalytic reaction pathway. The holes (which accumulate in the N-Bi2WO6 square-shaped discs) and Pd (which acts as an electron channel) can effectively inhibit the recombination of charge carriers, and Cu (which acts as the cocatalyst) can synergistically increase the H+ reduction rate. This study provides a new effective route for the design of high-performance heterostructures for efficient photocatalytic H2 production.