Insight into enhanced photocatalytic H2 production by Ni(OH)2-decorated ZnxCd1-xS nanocomposite photocatalysts

In this study, we investigate the synergetic effect of Ni(OH)(2)-decorated ZnxCd1-xS on photocatalytic performance. To explore the effect of ternary alloying and cocatalyst deposition on the structural, electronic, optical, and photocatalytic properties, a series of Ni(OH)(2)-ZnxCd1-xS nanocomposite photocatalysts with different x were synthesized and characterized by various techniques including XRD, Raman, TEM, UV-vis diffuse reflection, XPS, electrochemical impedance spectra. Results of XRD, Raman and TEM measurements show that well-crystallized hexagonal structured ZnxCd1-xS nanoparticles (NPs) were formed macroscopically with, microscopically, CdS- and ZnS-rich regions. XPS measurements indicate that Ni is existed in Ni2+ state on the surface of ZnxCd1-xS nanoparticles, and probably in the form of Ni(OH)(2). The Ni(OH)(2)-decorated Zn0.25Cd0.75S photocatalyst exhibits the highest H-2-production rate among all the samples, which is nearly 5 times that of pure CdS, while further increasing Zn content will suppress the photocatalytic activity. The enhanced photocatalytic H-2-production activity can be attributed to the properly balancing of negatively shifting conduction band edge while maintaining reasonably high visible-light absorption by forming Zn0.25Cd0.75S ternary alloys, and improved charge separation due to Ni(OH)(2) cocatalyst loading, which can serve as electron traps. (C) 2017 Elsevier B.V. All rights reserved.