Nanocrystals as Effective Electrocatalysts for the Hydrogen Evolution Reaction

We report enhanced electrocatalyst performance for the hydrogen evolution reaction (HER) due to the structural phase change of SnS thin films to SnS2 via a facile low vacuum annealing protocol in the presence of elemental sulfur. This sulfurization process resulting in the increased formation of nanocracks which serve as catalytic sites for hydrogen generation. Compact SnS thin films with large grain sizes demonstrate an improved current density of -6.15 mA/cm2 at relatively low overpotentials as compared to previous reports. After sulfurization, the obtained SnS2 thin films are used as an electrocatalyst for HER for the first time and achieve a significantly higher current density of -27.9 mA/cm2 with a corresponding Tafel slope of 85 mV/dec which can be attributed to a large number of nanoscale active sites. Our results demonstrate the potential of layered tin sulfide compounds as promising electrocatalysts for efficient and large-scale water splitting.