Amorphous NiFeB nanoparticles realizing highly active and stable oxygen evolving reaction for water splitting

The development of highly efficient and inexpensive catalysts for oxygen evolving reactions (OERs) is extremely urgent for promoting the overall efficiency of water splitting. Herein we report the fabrication of a series of amorphous NiFeB nanoparticles with varying atomic ratios of Fe to (Ni + Fe) (χ_Fe) by a facile chemical-reduction method. The amorphous NiFeB (χ_Fe = 0.20) nanoparticles, combining the merits of in situ formation of borate-enriched NiFeOOH catalytic surface layers, intrinsic amorphous nanostructures, and an optimized degree of Fe doping, displayed highly active electrocatalytic performance towards the OER in a broad range of pH values (from alkaline to neutral conditions). The catalyst exhibited a relatively low overpotential of 216 mV with a Tafel slope of 40 mV/dec on Ni foam and 251 mV with a Tafel slope of 43 mV/dec on glassy carbon at 10 mA/cm² in a 1 M KOH solution, demonstrating much greater OER efficiency than that of commercial RuO₂. Long-term stability testing of the OER performance of NiFeB (χ_Fe = 0.20) by chronoamperometry (overpotential (η) = 320 mV) over 200 h revealed no evidence of degradation. Facile, scalable synthesis and highly active water oxidation make the NiFeB nanoparticles very attractive for OER electrocatalysis.