Ru doped NiFe-LDH based on self-supporting electrode as efficient and stable OER electrocatalyst for alkaline water-splitting

Abstract

The development of non-precious metal OER electrocatalysts plays a crucial supporting role in the advancement of alkaline water-splitting. Herein, we prepared a series of self-supported OER electrocatalysts (Ru/NiFe-LDH-x/NF) using the strategy of Ru doping NiFe-LDH and in-situ growth on foam nickel. The results showed that Ru/NiFe-LDH-40/NF exhibited the best OER catalytic activity and stability, and ICP-OES indicated that the Ru content was only 1.05 wt%. In 1 M KOH, the overpotential of Ru/NiFe-LDH-40/NF is only 208 mV (10 mA cm-2). Even at high current densities of 100 and 300 mA cm-2, the overpotentials are only 271 mV and 296 mV, respectively, significantly better than commercial RuO2. Ru/NiFe-LDH-40/NF exhibits excellent reaction kinetics, with a Tafel slope of 30 mV dec-1 and a charge transfer impedance of 0.49 Ω. In addition, it remained stable after 100 h of continuous operation at 400 mA cm-2 without any significant performance degradation. DFT+U calculations show that Ru doping effectively optimizes the adsorption free energy of the intermediate *OOH in the rate determining step, thereby significantly improving reaction kinetics and catalytic activity. The decomposition voltage of Ru/NiFe-LDH-40/NF as an anode catalyst for overall water-splitting is only 1.436 V (10 mA cm-2).