Nanoscale-mixed ZnNiCu hydroxide composite catalyst for improved photocatalytic hydrogen evolution

Abstract

The advantage of a complex catalyst in which several catalysts are mixed is that the overall reaction rate can be efficiently increased by increasing each sub-reaction rate. Each constituent catalyst in the complex catalyst must be as well-mixed as possible—while maintaining high catalytic activity—owing to the short reaction time of these sub-reactions. This study reports a facile synthetic method to mix two catalysts homogeneously at the nanoscale while keeping their crystal structure intact. ZnNiCu hydroxide nanoplates with a mixed crystal structure composed of ZnNi and ZnCu hydroxides, which could promote H2O dissociative adsorption and H2 desorption, respectively, were synthesized by a simple cation exchange of ZnO nanoparticles and a precursor mixture of Ni and Cu. ZnNi and ZnCu hydroxides in the nanoplates were mixed at the nanoscale while maintaining their respective crystal structures; density functional theory calculations show that these structures could effectively perform H2O dissociative adsorption and H2 desorption, respectively, resulting in high activity in the overall photocatalytic hydrogen evolution reaction.