Simple and Facile Fabrication of Anion-Vacancy-Induced MoO3-X Catalysts for Enhanced Hydrogen Evolution Activity

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.