Development of Ni–Fe based ternary metal hydroxides as highly efficient oxygen evolution catalysts in AEM water electrolysis for hydrogen production

Abstract A number of mixed metal hydroxide oxygen evolution reaction (OER) catalysts i.e. Ni–Fe, Ni–Co, Ni–Cr, Ni–Mo, Ni–Fe–Co, Ni–Fe–Mo and Ni–Fe–Cr were prepared by cathodic electrodeposition and characterised by SEM, TEM, EDS, XPS and micro X-CT. The compositions of selected catalysts were optimised to give lower OER overpotentials in alkaline media. Further optimisation of Ni–Fe based ternary metal hydroxide catalysts such as Ni–Fe–Co and Ni–Fe–Mo was carried out, showing improved performance at high current densities up to 1 A cm−2 in 1 M NaOH, 333 K. The influence of electrodeposition parameters such as current density, pH, electrodeposition time and temperature on the electrocatalytic performance of ternary Ni–Fe–Co metal hydroxide was further investigated and optimised. The durability of the optimised catalyst was tested at a current density of 0.5 A cm−2 in an anion exchange membrane (AEM) water electrolyser cell at 4 M NaOH, 333 K, demonstrating stable performance over 3.5 h.