Transition-metal chalcogenides (TMCs) are cheap and abundant and have recently been demonstrated as promising electrocatalysts for sustainable and efficient water electrolysis. The existing TMC synthesizing methods are limited by difficulties in precise composition control and complexities in synthetic parameters, highlighting the need for a facile and viable strategy for direct synthesis of TMCs on conducting substrates. Here, we report a generalized approach for direct synthesis of a variety of high-efficient, robust TMCs and stoichiometric composition-controlled TMC catalysts on conducting three-dimensional porous substrates via an anion-assisted electrochemical deposition technique. Using this strategy, 10 different types of TMC electrocatalysts were designed and synthesized using representative transition-metal elements (Co, Fe, Mo, Ni, and W) and chalcogen elements (S and Se). In particular, NiS and FeSe exhibited excellent activity with overpotentials of 83 and 171 mV to reach a current density of 10 mA cm–2 in HER and OER, respectively. In addition, control over the stoichiometric composition was also demonstrated by adjusting the ratio of binary chalcogen anions, in turn allowing for the modification of catalytic properties. Furthermore, a water electrolysis cell with the NiS cathode and FeSe anode showed remarkable overall water splitting performance with a cell voltage of 1.52 V at 10 mA cm–2 and superior long-term stability for 100 h even at a high current density (100 mA cm–2), which was a significantly higher performance in comparison with the other reported TMC-based cells and the benchmark noble Pt/C∥IrO2 cell.

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Here,nonprecious high‐entropy chalcogenide glasses (N‐HECGs) consisting of Co, Fe, Ni, Mo, W, and Te are demonstrated in a first demonstration of acidic oxygen evolution reaction (OER). N‐HECGs electrocatalysts with high activity and stability are synthesized using a hierarchical hybrid approach based on a combination of electrochemical deposition and tellurization process. The as‐prepared CoFeNiMoWTe N‐HECGs electrocatalysts exhibit an amorphous, porous structure of arrayed nanosheets with abundant active sites and the increased valence states of metal cations due to the incorporated non‐metallic Te, enabling the enhancement of glass forming ability and the valence states of metal elements. Thanks to the combination of their unique geometrical and chemical structure, as well as high configuration entropy nature and high corrosion‐resistance ability, the resultant CoFeNiMoWTe N‐HECGs exhibit excellent acidic OER catalytic performance with a superior overpotential of 373 mV and outstanding stability of 100 h at the current density of 10 mA cm−2 in 0.5 m H2SO4. Moreover, the CoFeNiMoWTe‐based proton exchange membrane water electrolyzer is demonstrated to require a cell voltage of 1.81 V at 70 °C to obtain the practically high current density of 1 A cm−2, and exhibits remarkably long‐term stability for 100 h with small potential degradation of only 30 mV.

Advanced catalysts for clean hydrogen generation and storage offer an attractive possibility for developing a sustainable and ecofriendly future energy system. Transition metal oxides (TMO) are appealing candidates to be largely considered as electrode catalysts. However, for practical applications, there are still challenges—the intrinsic catalytic properties of TMOs should be further improved and TMOs should be synthesized by practical routes for cost-effective and scalable production of catalysts. Therefore, finding promising ways to fabricate highly active TMOs with outstanding electrochemical hydrogen evolution performance is required. Here, we present a direct and facile synthetic approach to successfully provide highly efficient MoO3−X catalysts with electrochemically active oxygen vacancies through a one-step thermal activation process on a Mo metal mesh. Variations in the oxidation states of molybdenum oxides can significantly increase the active sites of the catalysts and improve the electrochemical activity, making these oxide compounds suitable for hydrogen evolution reaction (HER). Compared to the bare Mo mesh and fully oxidized Mo (MoO3) electrodes, the fabricated MoO3−X electrode exhibits better electrochemical performance in terms of overpotentials and Tafel slope, as well as the electrochemical 1000 cycling stability, confirming the improved HER performance of MoO3−X. This provides new insight into the simple procedure suitable for the large-production supply.

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