Fe-Induced electronic optimization of mesoporous Co–Ni oxide nanosheets as an efficient binder-free electrode for the oxygen evolution reaction

Exploring efficient electrocatalysts with low production costs for the oxygen evolution reaction (OER) is significant for sustainable and scalable production of hydrogen through water electrolysis, while it still remains a challenge. Herein, mesoporous Fe-doped Co–Ni oxide (CoNiFeOx) nanosheets grown on nickel foam are synthesized by a facile two-step strategy (a combination of hydrothermal and post-annealing). Benefiting from the mesoporous nanosheet structure, endowing the catalysts with a high specific surface area (222.6 m2 g−1) and more active sites, and the optimized electronic structure due to the incorporation of Fe, the as-synthesized mesoporous CoNiFeOx nanosheets as a binder-free electrode exhibits remarkable OER activity with an overpotential of only 221 mV at a current density of 10 mA cm−2 and a small Tafel slope of 43.8 mV dec−1 in 1 M KOH solution. Besides, it displays excellent stability for over 250 h and no obvious activity decline is measured after the long-term stability test. Our strategy will provide a potential route to develop low-cost and high-performance electrocatalysts for the OER.