In-situ synthesis of microflower composed of N-doped carbon films and Mo2C coupled with Ni or FeNi alloy for water splitting

Abstract Water electrolysis represents a promising technology for the production of hydrogen fuels. High-performance and stable non-noble electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are urgently desired to improve the efficiency of water splitting for large-scale hydrogen production. Herein, a flowerlike heterojunction catalyst composed of N-doped carbon films and Mo2C nanoparticles strongly coupled with ultrasmall Ni or FeNi alloy (Ni-Mo2C/CF or FeNi-Mo2C/CF) is in-situ synthesized for efficient water splitting. The as-prepared samples with unique architecture and composition combine the synergistic effects of both geometric design and electronic modification, possessing plenty of active sites, robust heterostructures, abundant channels for rapid mass transport and electron/ion transfer, and the improved conductivity for high-efficiency charge exchange during electrocatalytic process. The optimized Ni-Mo2C/CF for HER and FeNi-Mo2C/CF for OER achieve overpotentials of 81 and 228 mV to reach 10 mA cm−2, respectively, in 1.0 M KOH. Furthermore, the FeNi-Mo2C/CF(+)//Ni-Mo2C/CF(−) alkaline water electrolyzer demonstrates a low cell voltage of 1.53 V at 10 mA cm−2, outperforming most ever-reported water electrolyzer cells, and impressive stability over 24 h at 50 mA cm−2. This work provides a facile and effective method to construct high-performance and non-precious metal electrocatalysts for commercial water splitting.