Boosting oxygen evolution reaction by synergistically coupling amorphous high-entropy borate FeCoNiMnBOx with MXene

Exploring high-efficient and stable electrocatalyst is essential for oxygen evolution reaction (OER) to deal with its slow kinetic process. Herein, a novel nanocomposite electrocatalyst coupling the amorphous high-entropy borate FeCoNiMnBOx with the high conductivity Ti3C2-MXene has been synthesized by a low-temperature liquid-phase reduction strategy. The FeCoNiMnBOx/MXene shows a low overpotential of 268 mV at a current density of 10 mA cm−2 with a Tafel slope of 39.8 mV dec−1 under alkaline conditions, better than that of pure FeCoNiMnBOx and noble metal RuO2 catalysts. The lamellar MXene in the composite can effectively suppress the aggregation of FeCoNiMnBOx and enhance the utilization of the active sites. The amorphous structure of FeCoNiMnBOx can expose more active sites. The strong interfacial bonding between MXene and FeCoNiMnBOx leads to redistribution of the interfacial charge and accelerates the charge transfer, which improve the electrical conductivity of the nanohybrids and promote the oxidation process of metal ions in FeCoNiMnBOx. The interface synergistically coupling effect to accelerate the kinetics of oxygen evolution reaction is demonstrated by in situ electrochemical impedance spectroscopy (EIS). This work provides a new branch for the design of high-efficient electrocatalysts for renewable energy applications.