Two-dimensional nickel hydroxide/sulfides nanosheet as an efficient cocatalyst for photocatalytic H2 evolution over CdS nanospheres

• Published in: Journal of colloid and interface science 2018-03, Vol.514, p.634-641
• Main Authors: Xie, Ying Peng, Zheng, Yunhui, Yang, Yongqiang, Jiang, Renzheng, Wang, Guosheng, Zhang, Yajing, Zhang, Enlei, Zhao, Liang, Duan, Chun-Ying
• Format: Article
• Language: English
• Subjects: CdS; Cocatalyst; Hydrogen; Ni(OH)2/Ni3S2/NixS6; Two-dimensional
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2017.12.080

A noble-metal-free 2D nanosheet composed of Ni(OH)2, Ni3S2 and NixS6 can effectively promote the charge transfer and separation, and thus substantially improve the photocatalytic H2 evolution activity and stability of CdS nanospheres. This cocatalytic function of 2D nanosheets on CdS is originating from a synergistic effect of Ni(OH)2 and nickel sulfides acting as the hole storage and surface reaction sites, respectively. [Display omitted] The intriguing features of two-dimensional (2D) materials such as better charge carrier separation and abundant surface reaction sites endow them with potential applications as cocatalysts in photocatalysis. In this paper, a ternary 2D nickel hydroxide/sulfides nanosheet composed of Ni(OH)2, Ni3S2 and NixS6 was loaded on CdS nanospheres by a simple chemical deposition route. The composition of nickel hydroxide/sulfides was determined clearly through an overall analysis using X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. Mott-Schottky, electrochemical impedance, steady-state and time-resolved photoluminescence spectroscopy were used to investigate the charge transfer process in CdS and Ni(OH)2/Ni3S2/NixS6-CdS. The results confirm that a synergistic effect of Ni(OH)2/Ni3S2/NixS6 on CdS has occurred under light irradiation, where the Ni(OH)2 and nickel sulfides act as hole storage and surface reaction sites, respectively, to promote the charge transfer on CdS. The improved charge transfer and separation efficiency as well as the increased surface reaction sites in Ni(OH)2/Ni3S2/NixS6-CdS finally result in a dramatically improved photocatalytic performance. The photocatalytic H2 evolution rate of Ni(OH)2/Ni3S2/NixS6-CdS is ca. 46 times higher than that of CdS, and the photocatalytic stability of CdS is also improved substantially under visible light irradiation.