Sulfur vacancies-induced Electron Bridge in Ni4Mo/Sv-ZnxCd1-xS regulates electron transfer for efficient H2-releasing photocatalysis

Despite the existence of plentiful photocatalyst heterojunctions, their separation efficiency and charge flow precision remain low on account of lacking interfacial modulation. Herein, through a defect-induced heterojunction constructing strategy, Ni4Mo alloys were in-situ grown on the unsaturated coordinated sulfur atoms of sulfur vacancies-rich ZCS (Sv-ZCS) via interfacial Ni-S covalent bonds. The experimental and theoretical results reveal that these unsaturated sulfur atoms induced by sulfur vacancies vastly facilitate to anchor more Ni-Mo nanoparticles and form abundant Ni-S covalent bonds, meanwhile, these sulfur vacancies could form dual internal electric field (IEF) and work with Ni-S covalent bonds as Electron Bridge to further accelerate photoelectrons transfer, as well as promote the activation of water molecules and the desorption of hydrogen proton. Accordingly, the optimized Ni4Mo/Sv-ZCS composite achieves an improved photocatalytic hydrogen evolution (PHE) rate of 94.69 mmol h(-1) g(-1) without an evident decrease after 6 cycles of photocatalytic tests, which is 21.2 and 1.94 times higher than those of Pt/ZCS and Ni4Mo/ZCS, respectively. This tactic opens a new way for optimizing ZnxCd1-xS-based heterojunctions by constructing sulfur vacancies and covalent bonds as Electron Bridge to enhance the activity of PHE. (c) 2023 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences Published by Elsevier B.V. All rights reserved.

Automated summary

Through a defect-induced heterojunction constructing strategy, Ni4Mo alloys were grown on sulfur vacancies-rich ZCS via interfacial Ni-S covalent bonds, resulting in enhanced photocatalytic hydrogen evolution rate and stability. The unsaturated sulfur atoms induced by sulfur vacancies facilitate the anchoring of Ni-Mo nanoparticles and the formation of abundant Ni-S covalent bonds, enabling efficient photoelectron transfer and activation of water molecules. The optimized Ni4Mo/Sv-ZCS composite exhibits significantly higher PHE rate compared to Pt/ZCS and Ni4Mo/ZCS, indicating the potential of constructing sulfur vacancies and covalent bonds as an electron bridge to enhance PHE activity.