Highly Efficient Hydrogen Evolution from Edge-Oriented WS<sub>2(1–<i>x</i>)</sub>Se<sub>2<i>x</i></sub> Particles on Three-Dimensional Porous NiSe<sub>2</sub> Foam

The large consumption of natural fossil fuels and accompanying environmental problems are driving the exploration of cost-effective and robust catalysts for hydrogen evolution reaction (HER) in water splitting. Tungsten dichalcogenides (WS<sub>2</sub>, WSe<sub>2</sub>, etc.) are promising candidates for such purpose, but their HER performances are inherently limited by the sparse catalytic edge sites and poor electrical conductivity. Here we demonstrate a highly active and stable HER catalyst by integrating ternary tungsten sulfoselenide WS<sub>2(1–<i>x</i>)</sub>Se<sub>2<i>x</i></sub> particles with a 3D porous metallic NiSe<sub>2</sub> foam, in which good electrical conductivity, good contact, large surface area, and high-density active edge sites are simultaneously obtained, thus contributing to outstanding catalytic performance: large cathode current density (−10 mA/cm<sup>2</sup> at −88 mV), low Tafel slope (46.7 mV/dec), large exchange current density (214.7 μA/cm<sup>2</sup>), and good stability, which is better than most reports on WS<sub>2</sub> and NiSe<sub>2</sub> catalysts. This work paves an interesting route for boosting HER efficiency of transition metal dichalcogenide catalysts.