Molybdenum-containing amorphous metal oxide catalysts for oxygen evolution reaction

Amorphous mixed metal oxide oxygen evolution reaction catalysts containing Mo, Co, and Fe were synthesized by a low energy required photochemical metal-organic deposition (PMOD) process. The composition of the ternary amorphous metal oxide catalyst film can be precisely controlled as to its precursor solution, and there was no phase segregation observed. The electrocatalytic activity of this ternary catalyst system was carefully mapped out as contour plots to illustrate the kinetics parameters such as onset potential, Tafel slope as well as the overall performance, i.e. the potential required to reach the benchmark current density. In this study, adding higher valence state material, Mo, into catalytic active metal oxides, such as CoOx and FeOx, to form Co50Mo50Ox and Fe50Mo50Ox could highly increase the catalyst stability. More importantly, the ternary metal oxide Fe10Co25Mo65Ox showed the advantage of the relatively low onset potential (1.52 V), low Tafel slope (∼31 mV/dec), lowest potential to reach the benchmark 1 mA/cm2 and a better stability for the oxygen evolution reaction in Mo/Co/Fe system.