Significantly Enhanced Photocatalytic Performance of the g-C 3 N 4 /Sulfur-Vacancy-Containing Zn 3 In 2 S 6 Heterostructure for Photocatalytic H 2 and H 2 O 2 Generation by Coupling Defects with Heterojunction Engineering.

Light-driven splitting of water to produce H 2 and reduction of molecular oxygen to synthesize H 2 O 2 from water are the emerging environmentally friendly methods for converting solar energy into green energy and chemicals. In this paper, vacancy defect and heterojunction engineering effectively adjusted the conduction band position of Zn 3 In 2 S 6 , enriched the electron density, broadened the optical absorption range, increased the specific surface area, and accelerated the charge carrier transfer and separation of g-C 3 N 4 /sulfur-vacancy-containing Zn 3 In 2 S 6 (CN/Vs-ZIS) heterostructures. As a result, all of the CN/Vs-ZIS heterostructures possessed greatly enhanced photocatalytic activities and the optimized sample 2CN/Vs-ZIS exhibited the highest visible-light photocatalytic performance. The rate of generation of H 2 of 2CN/Vs-ZIS under visible light (λ > 420 nm) was 6.55 mmol g -1 h -1 , which was 1.76 and 6.06 times higher than those of Vs-Zn 3 In 2 S 6 and g-C 3 N 4 , respectively, and the apparent quantum yield (AQY) was 18.6% at 420 nm. Meanwhile, the 2 h yield of H 2 O 2 of 2CN/Vs-ZIS was 792.02 μM, ∼4.72 and ∼6.04 times higher than those of pure Vs-Zn 3 In 2 S 6 and g-C 3 N 4 , respectively. The enhanced reaction mechanisms for the production of photocatalytic H 2 and H 2 O 2 were also investigated. This work undoubtedly demonstrates that the synergistic effects of defect and heterojunction engineering will be the great promise for improving the photocatalytic efficiency of Zn 3 In 2 S 6 -based materials.