Controlled growth of ZnS/ZnO heterojunctions on porous biomass carbons via one-step carbothermal reduction enables visible-light-driven photocatalytic H2 production

• Published in: Inorganic chemistry frontiers Vol. 6; no. 8; pp. 2035 - 2042
• Main Authors: Hai-Bo Huang, Yu, Kai, Jun-Tao, Wang, Jun-Ru Zhou, Hong-Fang, Li, Lü, Jian, Cao, Rong
• Format: Journal Article
• Language: English
• Published: London Royal Society of Chemistry 01.08.2019
• Subjects: Adsorption; Biomass; Conductors; Defects; Electrochemistry; Electron transfer; Heterojunctions; High temperature; Hydrogen production; Inorganic chemistry; Irradiation; Photocatalysis; Photocatalysts; Photoluminescence; Reduction; Separation; Spectra; Zinc oxide; Zinc sulfide
• ISSN: 2052-1545; 2052-1553
• DOI: 10.1039/c9qi00454h

For visible-light-driven H2 production, rational design of heterojunction photocatalysts might be a feasible strategy to achieve enhanced H2 evolution efficiency. Herein, we prepared ZnS/ZnO heterojunctions highly dispersed on porous biomass carbons (ZnS/ZnO@C) through a one-step carbothermal reduction process at elevated temperatures. By means of the proposed synthetic pathway, the ZnS/ZnO@C composites were enabled with visible-light-driven photocatalytic capacity, despite either ZnS or ZnO being catalytically inactive for H2 production under visible irradiation. The as-prepared photocatalyst with a 1 : 1 mole ratio of zinc and carbon sources at 800 °C displayed an optimal H2 production rate of ca. 37.1 μmol h−1 g−1. TEM images and UV–DRS spectra suggested that the formation of ZnS/ZnO heterojunctions would induce the generation of oxygen defects in ZnO to greatly promote visible light adsorption. Electrochemistry analyses and time-resolved photoluminescence spectra demonstrated that more efficient separation of photo-induced carriers took place via the interfaces of ZnO/ZnS heterojunctions, prolonging the charge separation lifetime. Moreover, porous biomass carbons would serve as electron conductors to efficiently improve the photo-induced electron transfer from the bulk of ZnS/ZnO to surfaces for boosting the reduction of H2O to H2. The ZnS/ZnO heterojunctions with oxygen defects coupled with porous biomass carbons jointly achieved highly efficient H2 production under visible irradiation. This work thus provided a facile means by using low-cost porous biomass carbons to design robust and flexible photocatalysts for visible-light-driven H2 production with high efficiency.