emaZero-additional-energy-consumption fabrication of a self-supported electrode: synergistic redox-corroding and boronizing engineering for overall water splitting

The non-precious metal-based materials show excellent catalytic activity for overall water splitting. However, it is still a challenge to meet the requirements of fabricating catalysts with cost-effective, high-performance, and large-scale production. In this paper, we report an energy-efficient, low-cost, scaled-up redox-corroding, and boronizing engineering method for transforming inexpensive nickel foam into highly active, flexible, and durable self-supported electrodes for overall water splitting. This work adopts a desirable redox-corroding and one-pot NaBH4 reduction reaction of nickel foam in aqueous solutions containing trivalent cations (Fe3+) under ambient temperature. This process results in well-distributed amorphous iron–nickel borides and hydroxides active materials that are grown in situ on the surface of porous nickel foam. The NiFeBx/NF//NiFe-OH/NF electrode pair shows low cell voltages of 1.63 V to achieve 10 mA cm−2 in 1 M KOH. More importantly, the NiFeBx/NF//NiFe-OH/NF electrode exhibits ultrahigh catalytic activities at high current densities, outperforming the benchmark electrode pair of Pt-C/NF//RuO2/NF. This inexpensive and simple controllable strategy provides Ni foam-substrate-derived electrodes with excellent catalytic activities and opens up new avenues for the rapid and simple fabrication of highly efficient electrodes for overall water splitting with large-scale applications.