Bifunctional electrocatalyst of CoxFey-C for overall water splitting

The exploitation of highly active, stable and inexpensive electrocatalysts with abundant elements of earth is the key to hydrogen production through water electrolysis. Herein, the precursors (cobalt-iron glycerate composites, CoxFeyG@F127 with different Co/Fe ratios) were prepared with the influence of polymeric surfactant Pluronic F127 by a hydrothermal process. The CoxFeyG@F127 were transformed into CoxFey alloy with a little of carbon (CoxFey-C) after calcination treatment. In these catalysts, the Co5Fe5-C nanospheres constructed with small nanoparticles can give full play to the synergistic effect of Co and Fe atoms, and significantly improve the catalytic activity. In 1.0 M KOH, the Co5Fe5-C electrocatalyst required a low overpotential of 245 mV for the oxygen evolution reaction (OER) and 165 mV for the hydrogen evolution reaction (HER) to achieve 10 mA cm−2, respectively. Based on the excellent catalytic performance for HER/OER, the bifunctional electrocatalyst of Co5Fe5-C were assembled into an alkaline electrolyzer, which can drive a current density of 10 mA cm−2 at 1.46 V and show outstanding performance for overall water splitting. © 2021 Elsevier B.V.