Construction of hollow tubular Co9S8/ZnSe S-scheme heterojunctions for enhanced photocatalytic H2 evolution

Herein, ZnSe nanoparticles with good visible-light response were in-situ deposited on the surface of the hollow tubular Co9S8 to form compact Co9S8/ZnSe heterojunctions via hy-drothermal and solvothermal methods. This architecture is beneficial to expose more active sites due to the uniform dispersion of ZnSe particles. Under visible light irradiation, the composites at the optimum Co9S8 amount (5 wt%) take on notably higher hydrogen evolution activity, 967.8 mmol/g/h, which is 3.1 times that of independent ZnSe (314.2 mmol/ g/h). A series of tests manifested that the Co9S8-ZnSe heterojunction significantly pro-motes the separation of photo-induced electron-hole pairs, notably improves hydrogen evolution kinetics and reduces the electron transfer resistance, which is responsible for the enhanced photocatalytic activity of the composites. Furthermore, the photocatalytic mechanism of the S-scheme heterojunction was proposed based on the measured energy band potentials. This work provides a strategy in constructing inexpensive heterojunction photocatalysts for enhancing the hydrogen evolution performance.(c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

In this study, ZnSe nanoparticles with good visible-light response were in-situ deposited on the surface of hollow tubular Co9S8 through hydrothermal and solvothermal methods, forming compact Co9S8/ZnSe heterojunctions. The composites with an optimum Co9S8 amount of 5 wt% exhibited significantly higher hydrogen evolution activity under visible light irradiation, 3.1 times that of independent ZnSe. The Co9S8-ZnSe heterojunction promoted the separation of electron-hole pairs, improved hydrogen evolution kinetics, and reduced electron transfer resistance, leading to the enhanced photocatalytic activity of the composites. The proposed S-scheme heterojunction photocatalytic mechanism was based on the measured energy band potentials. This work presents a strategy for constructing low-cost heterojunction photocatalysts to enhance hydrogen evolution performance.