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, NiCo, 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-FeCo 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.