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

Hydrogen peroxide (H 2 O 2 ) as a useful chemical has a wide range of applications, and the development of efficient semiconducting materials for H 2 O 2 production is deemed as a promising strategy to realize the energy conversion. In this paper, Cd x Zn 1-x S (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, 1) nano-branches are fabricated and the piezocatalytic and photocatalytic H 2 O 2 evolution performance are studied. Under ultrasound condition, the H 2 O 2 yield of as-synthesized solid solutions is all higher than those of pristine ZnS and CdS, and optimal evolution rate achieves 21.9 µmol g -1 h -1 for Cd 0.5 Zn 0.5 S without any sacrificial agent, while it is increased to 151.6 µmol 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 H 2 O 2 evolution for Cd 0.5 Zn 0.5 S, 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 H 2 O 2 generation pathways are originated from oxygen reduction by the sequential two-step single-electron reaction. This work opens a door for promoting the H 2 O 2 production from nanostructure and solid solution design.