NiFeMo alloy inverse-opals on Ni foam as outstanding bifunctional catalysts for electrolytic water splitting of ultra-low cell voltages at high current densities

NiFeMo alloy inverse-opals were created on nickel foam as an extraordinary bifunctional catalyst for alkaline electrolytic water splitting, achieving ultralow overpotentials of 33 and 249 mV for the hydrogen evolution reaction and 198 and 293 mV for the oxygen evolution reaction at current densities of 10 and 500 mA cm−2, respectively. Ultralow cell voltages of only 1.47 and 1.75 V are enough to deliver current densities of 10 and 500 mA cm−2, respectively, for overall water splitting, outperforming the benchmark couple, Pt/C and IrO2. The stability of the product is also outstanding, remaining stable after operations at an ultrahigh current density of 500 mA cm−2 for 50 h. The success of the product catalyst is attributed to the much increased active site number with the construction of inverse-opals on nickel foam and the much enhanced intrinsic activities of the active sites through synergistic effects between the three constituent elements.