One-step solid-phase boronation to fabricate self-supported porous FeNiB/FeNi foam for efficient electrocatalytic oxygen evolution and overall water splitting

Abstract

Development of cost-effective and efficient oxygen-evolution electrocatalysts is urgently required for exploring renewable hydrogen energy and realizing large scale water splitting. In this work, self-supported FeNi@FeNiB-700 has been developed by a facile and environment-friendly solid-phase boronizing process, and it exhibits excellent catalytic activity toward the OER. It requires overpotentials of 272 mV (η₁₀) and 399 mV (η₁₀₀) to deliver oxygen-evolution current densities of 10 and 100 mA cm⁻², respectively, outperforming many previously reported catalysts such as NiCo LDH nanosheets, Ni₃S₂/NF leaves, CoSe₂ NS@CP, etc. The impressive electrocatalytic performance is attributed to the formation of loose and porous bi-metal borides on the surface of the electrode, which guarantees enhanced active surface area and rapid charge/mass transfer. Moreover, the optimum pair of porous Ni–P foam (cathode) ‖ FeNi@FeNiB-700 (anode) in a two-electrode alkaline water electrolyzer also possesses high durability and only requires a cell voltage of 1.65 V to deliver 10 mA cm⁻². This study allows for large-scale application of cheap and efficient 3D bi-metal boride electrocatalysts for the oxygen evolution reaction and overall water splitting.