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

Abstract

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.