Highly efficient, stable, and low-cost catalysts for electrochemical water splitting play a critical role in promoting energy efficiency in the renewable hydrogen power-related industries. In this study, nonprecious metal carbides composed of Fe3 C and Mo2 C supported by carbon nanoplates are prepared and utilized as bifunctional electrocatalysts for overall water splitting. Spatially confined annealing of the polydopamine-coated metal precursors affords a structure containing porous cubes isolated by carbon nanoplates encapsulated with Fe3 C and Mo2 C nanoparticles. The hybrid electrocatalyst with a hierarchical structure, large surface area, and abundant exposed active sites benefits from efficient mass transport and more importantly the strong charge-transfer effect between the iron and molybdenum moieties. Under strong alkaline conditions, the optimized Fe3 C-Mo2 C hybrid (with a Fe/Mo ratio of 1 : 2) requires a low overpotential of 274 and 301 mV for the electrocatalytic oxygen evolution reaction at current densities of 10 and 100 mA cm-2 , respectively, accompanied with decent hydrogen evolution activity, thereby demonstrating efficient bifunctional electrocatalytic activity towards overall water splitting.
Keywords: carbides; charge transfer; electrocatalysis; hierarchical structures; water splitting.
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