Electrocatalytic performance of ReS2 nanosheets in hydrogen evolution reaction

Two-dimensional layered rhenium disulfide (ReS2) is regarded as an ideal high-performance catalyst for the hydrogen evolution reaction (HER) due to its distorted 1T crystalline structure, extremely weak interlayer coupling and unique Re–Re σ bond in the basal plane. However, relatively slow HER kinetics still restrict the further use of ReS2. In this work, ReS2 nanosheets were grown on a carbon cloth (CC) substrate by a hydrothermal method using a precursor solution of CS(NH2)2, NH4ReO4 and deionized water. With a decreasing CS(NH2)2 to NH4ReO4 molar ratio in the precursor solution, the ReS2 nanosheet distribution density on the CC substrate gradually decreases, resulting in a decline in HER activity. A ReS2 nanosheets/CC catalyst prepared with a CS(NH2)2 to NH4ReO4 molar ratio of 10:1 shows the optimal HER activity. It exhibits a low overpotential of 99 mV at 10 mAcm−2, a small Tafel slope of 222 mVdec−1, a large electrochemical surface area (ECSA) of 3375 cm2 and very high durability. From the variation of ECSA with the distribution density and growth time, we deduce that the active sites for the 2D ReS2 nanosheets exist on both the edge sites and basal planes. The active sites in the basal planes are ascribed to Re vacancies and defects.