Flower-like NiFe oxide nanosheets on Ni foam as efficient bifunctional electrocatalysts for the overall water splitting

Since the oxygen evolution reaction (OER) is a fundamental step in the overall water splitting process, it is necessary for an ideal catalyst to require a small amount of energy to overcome the energy barrier at the electrode-electrolyte interface. Therefore, developing highly active and integrated catalysts is of great significance. Herein, we present a facile and viable method to fabricate flower-like NiFe oxide nanosheets electrocatalysts that are directly grown on nickel foam substrates through a hydrothermal reaction. By tuning the Ni:Fe ratio, the as-synthesized NiFe oxide exhibits excellent catalytic activity that surpasses the activity of the RuO2 benchmark catalyst, when tested as an electrocatalyst for the overall water splitting reaction. More importantly, the optimized NiFe oxide electrode possesses excellent OER activity in 1 M KOH with small overpotentials of 255 and 280 mV at 10 and 50 mA cm ^-2 , respectively. When employed as a stable bifunctional catalyst to split water, this electrode achieved a current density of 10 mA cm ^-2 at a cell voltage of 1.59 V. This work presents a highly promising candidate for use as an electrode material and represents promising progress in its practical utilization and comprehensive industrialization.