Mn-mediated efficient oxygen evolution reaction on phosphorized NiFe electrocatalyst

The development of efficient electrocatalysts for oxygen evolution (OER) is very important for the practical application of water decomposition technology. Promoting the formation of high-oxidation-state transition metal species in a hydroxide catalyst may improve its catalytic activity in the oxygen evolution reaction, which remains difficult to achieve with current synthetic strategies. Herein, we reported the synthesis of Fe x Mn y-x nanosheets on nickel foam substrate subsequently by phosphating treatment (Fe x Mn y-x P/NF). The Mn-mediated and phosphating synergistic promoting the formation of high-oxidation-state Ni and/or Fe for improved oxygen evolution activity. In-situ Raman spectroscopy showed that the incorporation of Mn and P into the NiFe hydroxide caused a cathodic shift of the NiFe hydroxide (2 + ) to NiFeOOH (3 + δ) transition potential. Density functional theory calculations suggested that an elevated oxidation state for NiFe by Mn-mediated decreased the energy barriers of the rate-determining step (*OH → *O). As a result, an overpotential of 208 mV was achieved at a current density of 10 mA cm −2 in 1 M KOH. This work provides a new strategy and a deep insight into the construction of efficient NiFe-based water oxidation electrocatalysts.