Rational engineering bifunctional In2S3/Zn3In2S6 heterojunctions with double sulfur vacancies for efficient solar-driven photocatalytic H2 and H2O2 generation

The advanced photocatalytic technology with conversion of renewable solar energy to the clean hydrogen (H 2 ) and hydrogen peroxide (H 2 O 2 ) chemicals can effectively realize the national goals of “carbon emission peak & carbon neutrality”. To this end, the indium sulfide (In 2 S 3 )/zinc indium sulfide (Zn 3 In 2 S 6 ) heterojunctions with double sulfur vacancies (Vs) were successfully prepared by a feasible in-situ hydrothermal approach. The as-formed heterojunctions (denoted as Vs-ISZIS6) showed the high-performance bifunctional activities towards the both photocatalytic H 2 evolution and H 2 O 2 generation. Especially, the 10Vs-ISZIS6 sample presented the highest photocatalytic H 2 production rate (7051 μmol/h/g), which is 32.1, 2.0, 14.4, and 1.4-folds greater than that of In 2 S 3 , Zn 3 In 2 S 6 , VS-In 2 S 3 , and Vs-Zn 3 In 2 S 6 , respectively. In addition, the 20Vs-ISZIS6 heterojunction possessed the optimum concentration of H 2 O 2 production with reaching 256.4 μM under 2 h of visible-light irradiation. The boosted photocatalytic performances might be caused by the synergistic effect of the presence of Vs and the construction of heterostructure between Vs-In 2 S 3 and Vs-Zn 3 In 2 S 6 , leading to the increasing visible-light absorption and promoting the photogenerated carriers separation efficiency. As a result, the possible mechanism of improved photocatalytic performances of the Vs-ISZIS6 heterojunctions was proposed. This work offers an available avenue for developing of nanostructured heterojunctions for sustainable solar-to-chemical fuel conversion.