Amorphous Fe–Ni–P–B–O Nanocages as Efficient Electrocatalysts for Oxygen Evolution Reaction

Electrocatalysts are one of the most important parts for oxygen evolution reaction (OER) to overcome the sluggish kinetics. Herein, amorphous Fe-Ni-P-B-O (FNPBO) nanocages as efficient OER catalysts are synthesized by a simple low-cost and scalable method at room temperature. The samples are chemically stable, in clear contrast to reported unstable or even pyrophoric boride samples. The Fe/Ni ratio of the FNPBO nanocages can be continuously adjusted to optimize the OER catalytic performance. The FNPBO nanocages composed of multicomponent elements can weaken the metal-metal bonds, thus rearranging the electron density around the catalytic metal atom centers and reducing the energy barrier for intermediate formation. Hence the optimized FNPBO (Fe_6.4Ni_16.1P_12.9B_4.3O_60.2) catalyst shows superior intrinsic electrocatalytic activity for OER. The low overpotential to afford the current density of 10 mA cm^-2 (236 mV), the small Tafel slope (39 mV dec^-1), and the high specific current density (26.44 mA cm^-2) at a given overpotential of 300 mV make a sharp contrast to state-of-the-art RuO₂ (327 mV, 136 mV dec^-1, and 0.028 mA cm^-2, respectively).