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

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 con-stituent catalyst in the complex catalyst must be as well-mixed as possibledwhile main-taining high catalytic activitydowing 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. (c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.