Crystalline and amorphous phases: NiFeCo tri-metal phosphide as an efficient electrocatalyst to accelerate oxygen evolution reaction kinetics

To solve the problem of low hydrogen production efficiency from water electrolysis, increasing research is focusing on improving the efficiency of the complex oxygen evolution reaction (OER) that occurs at the anode. The preparation of high-efficiency OER electrocatalysts is key to improving the OER efficiency and the only way forward. In this work, a NiFeCo ternary OER high-efficiency electrocatalyst, NiFeCoP@CAP/NF, comprising coexisting crystalline and amorphous phases (CAP), was prepared on nickel foam (NF) by a simple one-step hydrothermal reaction and high-temperature gas-phase phosphating. The as-synthesized catalyst exhibits an ultralow overpotential of 202 mV (10 mA cm −2 ) in 1 M KOH solution with a Tafel slope (η10 = 202 mV) of 28.9 mV dec −1 . Further, it is understood that owing to the combination of the crystalline and amorphous phases, the catalyst can rapidly transform the amorphous phase into the true active (NiOOH) phase of the OER process while retaining the fast charge transport properties of the crystalline phase, as observed by in situ Raman analysis.