Hydrogen is the most desirable green energy carrier and electrocatalytic hydrogen evolution reaction (HER) from water is a promising route for hydrogen production. The search for efficient, low-cost HER catalysts is a challenging and attracting topic. In this work, we report that inorganic fullerene-like WS₂ supported Pd nanoparticles (Pd/WS₂), with Pd loading of 0.76 wt%, are active for electrocatalytic HER conducted in 0.5 M H₂SO₄ solution, with overpotential at 10 mA cm⁻² current density of ~130 mV and Tafel slope of 82.4 mV dec⁻¹, which is comparable to that of Pt/WS₂ (0.88 wt% Pt loading) with higher costs. Characteristic results indicate that WO₃ impurities were in-situ produced on the WS₂ surface and the Pd NPs are primarily located inside the WS₂ nanocages. Contrasting experiments suggest that the WO₃ impurities play a crucial role in generating H_ads intermediate and the Pd NPs are active sites of H₂ production, and a reaction mechanism is proposed. The Pd/WS₂ catalyst also shows good long-term stability owing to the location of Pd NPs inside the WS₂ cages. The high HER activity, low costs and good stability make the Pd catalyst a potential alternative to Pt catalyst for HER. ... Read more