Piezocatalytic and Photocatalytic Hydrogen Peroxide Evolution of Sulfide Solid Solution Nano-Branches from Pure Water and Air

Hydrogen peroxide (H2O2) as a useful chemical has a wide range of applications, and the development of efficient semiconducting materials for H2O2 production is deemed as a promising strategy to realize the energy conversion. In this paper, CdxZn1-xS (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, 1) nano-branches are fabricated and the piezocatalytic and photocatalytic H2O2 evolution performance are studied. Under ultrasound condition, the H2O2 yield of as-synthesized solid solutions is all higher than those of pristine ZnS and CdS, and optimal evolution rate achieves 21.9 mu mol g(-1) h(-1) for Cd0.5Zn0.5S without any sacrificial agent, while it is increased to 151.6 mu mol g(-1) h(-1) under visible light irradiation. The piezo/photoelectrochemical tests, piezoresponse force microscopy (PFM), and computational simulation reveal that the nano-branch structure benefits the mechanical energy conversion more, favoring the H2O2 evolution for Cd0.5Zn0.5S, and a higher concentration of charge carriers is generated in photocatalysis. The active radical trapping and in situ electron spin resonance (ESR) experiments demonstrate that both of the H2O2 generation pathways are originated from oxygen reduction by the sequential two-step single-electron reaction. This work opens a door for promoting the H2O2 production from nanostructure and solid solution design.