Ni optimizes Ir reaction pathway through IrNi alloy synergistic effect to improve overall water splitting efficiency

Ir-based synergistic interaction with transition metal alloys for catalytic overall water splitting holds great promise for application. However, the role of the transition metal in the alloy for the catalytic reaction is not well understood. Here, we report new IrNi porous miscible alloy nanoparticles (IrNi PMAN) for overall water splitting in 1 M KOH. IrNi PMAN exhibits excellent bifunctional electrocatalytic activity with overpotentials of only 14 mV and 245 mV for HER and OER at 10 mA cm−2, respectively. What's more, it only requires 43 mV and 324 mV for HER and OER at high current densities of 100 mA cm−2, respectively. In addition, IrNi PMAN as two-electrode electrolyzer produces a current density of 100 mA cm−2 at 1.69 V. The synergistic effect of the alloys is the main factor for the high catalytic efficiency. Notably, DFT calculations indicate that Ni adsorbs OH- more rapidly and accelerates Ir adsorption and conversion of OER intermediates, thus improving the stability and activity of overall water splitting.