Shrunken hollow Mo-N/Mo-C nanosphere structure for efficient hydrogen evolution in a broad pH range

Finding a non-noble metal (NNM) electrocatalyst with comparative hydrogen evolution reaction (HER) activity in a broad pH range is essential but challenging. Here, we report a unique shrunken hollow spherical shell with Mo ₂ N and Mo ₂ C dual active phases encapsulated by nitrogen-doped carbon (Mo-N/C@N-C). As NNM electrocatalyst, it shows high HER activity and stability in a broad pH range. This material can be synthesized by pyrolysis of sulfonated polystyrene@polyaniline-MoO _x sphere-like precursors using sulfonated polystyrene as template and polyaniline as carbon and nitrogen source. In an alkaline solution, the as-prepared Mo-N/C@N-C only needs an overpotential of 135 mV to reach the current density of 10 mA cm ⁻² , and exhibits high electrochemical and structural durability. The catalyst also possesses similar performance in acidic and neutral media, making it a suitable candidate for hydrogen production in all pH media. Such excellent catalytic performance is mainly driven by the synergy of abundant Mo ₂ N and Mo ₂ C dual active centers, and shrunken hollow sphere structures with high packing density, as well as the N-C active site and protection of N-doped carbon frameworks.