Cooperative photocatalytic H2 liberation and benzyl alcohol C-C coupling reactions over Zn2In2S5 embracing Zn/In dual vacancies

Abstract

Photocatalytic benzyl alcohol (BA) conversion is promising to coproduce H2 and value-added chemicals but is subject to low efficiency. Here, a dual-defects engineering strategy has been applied to Zn2In2S5, i.e. constructing both Zn and In vacancies (VZn/VIn), which enables efficient BA conversion to H2 and valuable carbon-carbon (C-C) coupling compounds. Compared with previous strategies using VZn defect alone, our dual-defects strategy is more effective in separating photocarriers thereby can provide more usable photocarriers for BA conversion. In the optimized dual-defects’ content, Zn2In2S5 can deliver an apparent quantum yield (AQY) as high as 8.3% at 420 ± 20 nm for the generation of the C-C coupling compounds. DFT calculation reveals that the VZn/VIn dual defects can (1) endorse high mobility and high reducing power to the photo-generated electrons, (2) enlarge the energetically downhill step for the formation of ketyl radicals, and (3) lower the energy barriers for the coupling of ketyl radicals. These findings not only expand the toolbox for the design and modification of semiconductor photocatalysts but also provide an in-depth understanding of the role of various defects in photocatalytic BA conversion Abstract text goes here.