Structural and Electronic Engineering of Co-doped Ni₃C Nanoparticles Encapsulated in Ultrathin Carbon Layers for Hydrogen Evolution Reaction

With resurgent interest in green hydrogen as a key element in the transition to a renewable-energy economy, developing efficient, earth-abundant, and low-cost catalysts for hydrogen evolution reaction (HER) is becoming increasingly important but is still very challenging. Herein, we report the synthesis of Co-doped Ni3C nanoparticles encapsulated in ultrathin carbon layers (CNCC) by in-situ thermal decomposition of organic-inorganic hybrid as high-performance HER electrocatalysts. Experimental and density functional theory studies evidence that the substantial high-index (113) surfaces in synergy with a few atomic carbon layers contribute significantly to the activity and stability, while the electronic structure of Ni3C is optimized through tuning the Co content to enhance the intrinsic kinetics for HER. The CNCC exhibits excellent HER activities with overpotentials at 10 mA cm(-2) (eta(10)) of 102 and 69 mV and Tafel slopes of 74 and 43 mV dec(-1) in respective neutral and alkaline media along with a superior stability without noticeable decay up to 100 h. More importantly, the CNCC outperforms the benchmark Pt/C catalyst under high current density (>38 mA cm(-2)) in an alkaline electrolyte, showing great potential for practical hydrogen production.