One-Step Solid-phase Boronation to Fabricate Self-Supported Porous FeNiB/FeNi Foam for Efficient Electrocatalytic Oxygen Evolution and Overall Water Splitting

Development of cost-effective and efficient oxygen-evolving 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, which exhibits excellent catalytic activity toward OER. It requires overpotentials of 272 mV (η10) and 399 mV (η100) to deliver oxygen-evolving current densities of 10 and 100 mA cm−2, respectively, outperforming many of 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 electrode, which guarantees the enhanced active surface area and rapid charge / mass transfer. Moreover, optimum pair of porous Ni–P foam (cathode) ǁ FeNi@FeNiB-700 (anode) in two-electrode alkaline water electrolyzer also possesses high durability and only demands 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 oxygen evolution reaction and overall water splitting.