Significance of Surface Trivalent Manganese in the Electrocatalytic Activity of Water Oxidation in Undoped and Doped MnO2 Nanowires

Abstract

AbstractThe oxygen‐evolution reaction (OER) is a bottleneck reaction because of a significant overpotential loss in water electrolysis. Currently, MnO2‐based materials are promising candidates for OER electrocatalysts owing to their abundance and excellent properties. Herein, a hydrothermal method was used to prepare MnO2 nanowires with different diameters. Furthermore, an impregnation method was applied to dope MnO2 nanowires with Ca and Ag ions. Characterization by TEM, XRD, Raman, X‐ray photoelectron spectroscopy (XPS), N2 adsorption, and linear‐scanning voltammogram analysis were performed on these materials. It was found that the OER activity of as‐prepared and doped MnO2 nanowires is highly dependent on the fraction of surface trivalent manganese in MnO2 nanowires. Density functional theory calculations of doped MnO2 revealed the delicate change of the electronic properties of MnO2 nanowires after doping.