Formation of ReS2/ReO3 semiconductor-metal heterostructure boosts electrocatalytic performance of pristine ReS2 nanoparticles in hydrogen evolution reaction

Electrocatalytic hydrogen evolution reaction (HER) over transition metal dichalcogenides (TMDs) has recently attracted considerable attention as one of the most promising pathways for hydrogen generation. Specifically, rhenium disulfide (ReS2) has been demonstrated as a particularly active and efficient HER electrocatalyst, which was subsequently linked to its unique, layer-independent electronic and phonon structure. Therefore, there is an immediate quest to develop an efficient and cost-effective synthesis procedure of ReS2. Here, we designed a novel and facile manufacturing of ReS2 nanoparticles (NPs) by wet chemical synthesis combined with an annealing procedure. The crystallinity of NPs and phase composition can be tuned by careful selection of the process parameters. We found that our synthesized NPs are superior when it comes to electrocatalytic hydrogen generation with respect to commercially available ReS2. This observation can be explained by the formation of ReS2/ReO3 nanocomposite, where a tiny fraction of metallic ReO3 decorates ReS2 NPs. We applied the density functional theory (DFT) calculations to provide insight into the electronic structure of ReS2/ReO3 and to clarify the beneficial impact of ReO3 on the electrocatalytic performance of ReS2 NPs. Our results have important implications for optimizing the electrocatalytic HER performance of ReS2 NPs and provide a facile strategy for their efficient synthesis.