Magnetic-field-induced rapid synthesis of defect-enriched Ni-Co nanowire membrane as highly efficient hydrogen evolution electrocatalyst

Metallic Ni-based materials are promising electrocatalysts for commercial alkaline water electrolysis towards hydrogen generation. It is therefore desirable to develop low-cost and controllable synthesis protocols for efficient Ni-based electrocatalysts. Here we report a rapid one-step method to fabricate self-supported membranes of highly-conductive Ni-Co nanowires, which are formed via self-assembly of reduced Ni/Co nanoparticles under a rotating magnetic field. The Ni-Co nanowires are composed of Co nanoparticles and NiCo alloy nanoparticles domains, with abundant inherent interface defects due to incomplete alloying and insufficient Ostwald ripening during the assembly. Nanowires with different Ni/Co ratios are tested as the HER electrodes in comparison to pure Ni mesh and Ni foam electrodes; And the Ni0.50Co0.50 nanowire electrode gives the most optimized performance. The HER activity shows little degradation for nearly 100 h. These nanowire electrodes are superior to the state-of-the-art metallic Ni-based ones. This facile technology may represent a critical step towards scalable production of highly active and durable metallic Ni-based electrocatalysts for industry applications.