Integration of ohmic junction and step-scheme heterojunction for enhanced photocatalysis

• Published in: Journal of colloid and interface science Vol. 654; pp. 134 - 149
• Main Authors: Zhao, Wei, Liu, Siying, Liu, Yun, Yang, Shuo, Liu, Benzhi, Hong, Xuekun, Shen, Junyu, Sun, Cheng
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 15.01.2024
• Subjects: Heterojunction; Ohmic junction; Photocatalysis; S-scheme; Ohmic junction; S-scheme; Photocatalysis; Heterojunction
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2023.09.158

A novel Cu2WS4/MoS2-Au plasmonic S-scheme heterojunction photocatalyst is successfully synthesized for the first time. [Display omitted] •Cu2WS4/MoS2-Au plasmonic S-scheme heterojunction was constructed for the first time.•Cu2WS4/MoS2-Au demonstrated desirable activity for removal of Cr6+ and Benzophenone-1.•Effective charges separation and constructed S-scheme heterojunction accounts for the outstanding photocatalytic activity.•Comprehensive experimental and DFT studies of Cu2WS4/MoS2-Au was conducted to reveal the photocatalytic mechanism. A novel and efficient photocatalyst, Cu2WS4/MoS2-Au plasmonic Step-scheme (S-scheme) heterojunction, was constructed for the first time and applied to remove environmental pollutants. Among all the prepared photocatalysts, the. Cu2WS4/MoS2-Au-5 exhibited the highest catalytic activity with an 89.1% reduction efficiency for Cr6+ and a 98.7% oxidation efficiency for Benzophenone-1 (BP-1) under visible light irradiation. The Cu2WS4/MoS2-Au photocatalyst exhibits stable performance and efficient photocatalytic activity due to effective charge separation, enhanced light absorption from localized surface plasmon resonance (LSPR) of gold nanoparticles, and the formation of an S-scheme heterojunction with strong oxidation–reduction capabilities. In addition, through analysis of experiments and theoretical calculations, it is speculated that the Cu2WS4/MoS2-Au follows a typical S-scheme photogenerated carrier transferring mechanism, which is verified by the finite difference time domain simulation, the free radical quenching experiments, the electron paramagnetic resonance analysis and the simulated charge density distribution. More importantly, the simulations of the work function and charge density distribution confirm the built-in electric field and the ohmic junction have been established at the interfaces between the Cu2WS4 and MoS2 (Cu2WS4/MoS2) as well as the interface between MoS2 and Au (MoS2-Au), respectively. The built-in electric field and ohmic junction enable efficient separation of photogenerated electrons and holes, ensuring the superior catalytic oxidation and reduction activities of the Cu2WS4/MoS2-Au photocatalyst. Finally, we propose a photocatalytic mechanism for the Cu2WS4/MoS2-Au plasmonic S-scheme heterojunction based on experimental results and simulated calculations. The research results of this study are significance for the development of the plasmonic S-scheme photocatalytic system.