Electron Accumulation Effect over Osmium/Erlichmanite Heterointerfaces for Intensified pH-Universal Hydrogen Evolution

Osmium (Os), as the cheapest platinum (Pt)-group metal, has rarely been utilized in electrocatalysis resulting from excessive adsorbability. Interface engineering can effectively regulate the electronic state to strengthen/weaken the adsorption behaviors of key intermediates, thereby enhancing the intrinsic catalytic activity. Herein, theoretical calculations uncover the electron accumulation effect over the osmium/erlichmanite (Os/OsS2) heterointerface, accompanied by a negative shift of the d-band center. Then, the hydrogen adsorption on resultant electron-deficient Os sites effectually weakens, leading to high catalytic activity toward hydrogen evolution reaction (HER). Through a partial sulfurization strategy assisted by the eutectic salt system, the desired Os/OsS2 heterostructure is constructed as the pH-universal HER catalyst. Owing to the rapid interfacial electron transmission, high specific activity, and favorable reaction kinetics over the heterostructure, Os/OsS2 merely needs overpotentials of 29, 37, and 58 mV at the current density of 10 mA cm–2 in acidic, alkaline, and neutral media, respectively, which are all comparable to commercial Pt catalysts. Impressively, the price activity of the Os/OsS2 catalyst is 14.4 and 2.5 times higher than that of the Pt catalyst at overpotentials of 10 and 50 mV in acidic media, respectively. Thorough insight into the structure–activity relationship of electron-accumulated heterointerfaces can offer profound enlightenment for the rational design of noble metal-based catalysts.