Trinary metal oxides of Co, Ni, and Mn as efficient overall water splitting catalyst

The development of inexpensive, highly effective and durable electrocatalysts for hydrogen production via water electrolysis is of paramount importance. Transition metal oxides, owing to their simplicity in preparation and cost-effectiveness, have been widely investigated, particularly cobalt, nickel, and manganese oxides. Inspired by the synergies of the ternary cathode materials of lithium-ion batteries (LiNi_xMn_yCo_1-x-yO₂, NMC), a simple and feasible method was used to prepare a graphite plate as the support, and Ni and Mn were co-doped with Co₃O₄ as an efficient water decomposition catalyst. Experimental studies indicated that the 10% Ni and 10% Mn co-doped Co₃O₄ (Co_2.4Ni_0.3Mn_0.3O₄, CNM-811) exhibited the lowest overpotential in the oxygen evolution reaction (OER), with CNM-811 achieving an overpotential of 338 mV at 30 mA cm⁻² in NaOH aqueous solution, the Tafel slope is 79.71 mV dec⁻¹. In the hydrogen evolution reaction (HER), an overpotential of 190 mV was attained at 10 mA cm⁻². In overall water splitting, a cell voltage of 2.048 V was achieved at 100 mA cm⁻², which was superior to many analogous catalysts reported today.