Low-temperature synthesis of molybdenum sulfides, tungsten sulfides, and composites thereof as efficient electrocatalysts for hydrogen evolution reaction

Abstract

In this work, we report a one-step approach for synthesizing molybdenum sulfides and tungsten sulfides, using (N2H5)(2)MS4 (M = Mo, W) as highly energetic self-catalytic redox precursors and inducing a thermolysis process at various temperatures. These materials' thermodynamic advantages facilitate the formation of molybdenum/tungsten sulfides at low temperatures. As expected, MoSx-100 degrees C (which features the [Mo3S13](2-) active site model) exhibits the highest catalytic activity of the reported molybdenum sulfides. In addition, an optimized sample of crystalline WS2 was reported to produce hydrogen at 400 degrees C. Furthermore, the combination of carbon materials significantly enhanced the hydrogen production performance. The optimal sample of reduced graphite oxide (rGO)/MoSx-100 degrees C required an overpotential of only 125 mV to achieve a current density of 10 mA cm(-2) and a shallow Tafel slope of 48.8 mV dec(-1); this was attributed to the increased charge transfer from rGO. Furthermore, the catalyst exhibited good stability after 2000 cycles and 12 h of testing. This work may provide an alternative approach for the large-scale synthesis of transition metal dichalcogenides in high-performance catalyst applications.