Composition-controlled high entropy metal glycerate as high-performance electrocatalyst for oxygen evolution reaction

Direct growth of novel high entropy glycerate (HEG) on Ni foam using a facile microwave-assisted solvothermal method is demonstrated. The effect of adding Ti, V, Cu, Zn, and/or Mo into a baseline quinary-metal HEG, consisting of Cr, Mn, Fe, Co, and Ni, on the electrocatalytic performance is investigated. The quinary-metal HEG shows an overpotential of 307 mV at 50 mA cm⁻² (η₅₀). We demonstrate that the catalytic activity can only be enhanced via doping with desired metals. The additions of Ti, V, and Zn lead to enhanced electrocatalytic performances, exhibiting η₅₀ of 254, 283, and 289 mV, respectively. The co-doping of Ti and Zn into the quinary-metal HEG results in a synergistic effect, giving robust catalytic activity with an ultra-low overpotential of 251 mV at 50 mA cm⁻² and a low Tafel slope of 42.3 mV dec⁻¹, and durable stability in 1 M KOH electrolyte for 60 h at different current densities of 10 and 100 mA cm⁻². Also, phase transformation of the metal glycerate into metal (oxy)hydroxide during OER is investigated using various in situ and ex-situ analyses. Density functional theory (DFT) calculation validates the synergistic effect of addition of Ti and Zn in HEG system.