In Situ-Fabricated In2S3-Reduced Graphene Oxide Nanosheet Composites for Enhanced CO2 Electroreduction to Formate

The use of renewable electricity to catalyze carbon dioxide reduction is a promising method for CO 2 utilization. However, the lack of highly efficient catalysts for CO 2 reduction seriously limits its industrial applications. As a prototype, an ultrathin indium sulfide nanosheet (In 2 S 3 NS) was synthesized and fabricated in situ on reduced graphene oxide (RGO) to obtain an In 2 S 3 –RGO composite. Induced by the two-dimensional (2D) structure of graphene oxide, the thickness of the In 2 S 3 NSs was reduced from 30.2 to 3.9 nm. Simultaneously, the (440) plane of In 2 S 3 NSs was preferentially grown parallel to the graphene plane, which was proven to possess a higher selectivity in catalyzing CO 2 electroreduction to formate than the (111) and (311) planes by density functional theory calculations. Attributed to the 2D structure and full exposure of the (440) planes, a large electrochemically active surface area and high density of optimum active sites were both realized on the In 2 S 3 –RGO hybrids, leading to 91% faradaic efficiency of formate at −1.2 V versus The reversible hydrogen electrode in 0.1 M KHCO 3 is 3.5 times that of bulk In 2 S 3 (26%). Our work provides an effective way to prepare 2D transition metal catalysts with controllable crystal face exposure for specific reactions.