Ternary core-shell ZnO nanorods: A strategy for high-performance photocatalytic hydrogen evolution

Abstract

Solar-driven water splitting devoid of noble-metal co-catalysts is a promising and cost-efficient strategy for the production of clean and sustainable energy, namely hydrogen. The primary impediment to the practical application of photocatalysts lies in the efficiency of separation of photo-induced charge carriers. Herein, two core–shell ternary nanorod photocatalysts based on ZnO, ZnO@CuS@ZnS and ZnO@ZnS@CuS, were obtained via a facile surface sulfidation strategy. Intriguingly, it was discovered that the performance of hydrogen evolution of these photocatalysts was contingent upon the sequence of sulfidation. Meanwhile, the as-prepared photocatalysts displayed distinct advantages in different aspects. ZnO@CuS@ZnS exhibited a lower activation energy barrier, while ZnO@ZnS@CuS presented a more suppressed electron-hole pairs recombination. The composites exhibited high-efficiency of hydrogen evolution rates, 2.79 µmol·mg⁻¹·h⁻¹ (ZnO@CuS@ZnS) and 9.48 µmol·mg⁻¹·h⁻¹ (ZnO@ZnS@CuS), along with stable (20 h) performance. This phenomenon has been ascribed to the development of an n-p heterojunction structure, Z-scheme charge transfer mechanism, and the high-performing light-triggered charge separation to relatively extended lifetimes of 5.06 µs and 6.06 µs, respectively. This research may deliver significant understanding of the designation of economical and scalable ZnO-based heterojunction photocatalysts for hydrogen evolution reactions in photocatalysis.