In2O3/In2S3 Heterostructures Derived from In‐MOFs with Enhanced Visible Light Photocatalytic Performance for CO2 Reduction

A series of In2O3/In2S3 core‐shell heterostructures, derived from metal‐organic‐frameworks (MOFs), were successfully synthesized via a two‐step solvothermal route with different addition amount of sulfur‐bearing reagent (L‐cysteine, L‐Cys), which were used as photocatalysts for CO2 reduction with water vapor. The results indicated that 1.2‐In2O3/In2S3 with optimized L‐Cys addition amount had the highest production rate of CH4 (14.3 μmol gcat−1 h−1) and CO (2.59 μmol gcat−1 h−1). Pure In2O3 and 2.4‐In2O3/In2S3 with excess L‐Cys addition exhibited higher H2 production rate but lowest CO2 photoreduction activity. As the characterizations revealed, amorphous shell with abundant In2O3/In2S3 heterostructures greatly improved the separation efficiency of photo‐induced charge carriers and visible light harvesting ability, which promoted the photoreduction of CO2 consequently. However, over‐addition of sulfur‐bearing reagent destroyed the heterostructures of shell layer and turned them into thickened In2S3 crystal layer. This substitution not only reduced the amount of heterostructures, but also hindered the adsorption of CO2 on the reactive surface. The formation of In2O3/In2S3 heterostructures enhanced the activity of photocatalytic CO2 reduction by improving the charge carriers separation and visible light response. Besides, the ratio of the reduction products altered with the distribution of the heterostructures. The samples with heterostructures constructed in the shell layer preferred the photoreduction of CO2 and produced more CH4 and CO than over‐sulfurized samples whose surface was totally covered by In2S3 phase.