General Synthesis of Metal Indium Sulfide Atomic Layers for Photocatalysis.

The metal indium sulfides have attracted extensive research interest in photocatalysis due to regulable atomic configuration and excellent optoelectronic properties. However, the synthesis of metal indium sulfide atomic layers is still challenging since intrinsic non-van-der-Waals layered structures of some components. Here, a surfactant self-assembly growth mechanism is proposed to controllably synthesize metal indium sulfide atomic layers. Eleven types of atomic layers with tunable compositions, thickness, and defect concentrations are successfully achieved namely In 2 S 3 , MgIn 2 S 4 , CaIn 2 S 4 , MnIn 2 S 4 , FeIn 2 S 4 , ZnIn 2 S 4 , Zn 2 In 2 S 5 , Zn 4 In 16 S 33 , CuInS 2 , CuIn 5 S 8 , and CdIn 2 S 4 . The typical CaIn 2 S 4 shows a defect-dependence activity for CO 2 photoreduction. The designed S vacancies in CaIn 2 S 4 can serve as catalytic centers to activate CO 2 molecules via localized electrons for π-back-donation. The engineered S vacancies tune the non-covalent interaction with CO 2 and intermediates, manages to tune the free energy, and lower the reaction energy barrier. As a result, the defect-rich CaIn 2 S 4 displays 2.82× improved reduction rate than defect-poor CaIn 2 S 4 . Meantime, other components also display promising photocatalytic performance, such as Zn 2 In 2 S 5 with a H 2 O 2 photosynthesis rate of 292 µmol g -1  h -1 and CuInS 2 with N 2 -NH 4 + conversion rate of 54 µmol g -1  h -1 . This work paves the way for the multidisciplinary exploration of metal indium sulfide atomic layers with unique photocatalysis properties.