Oxygen Evolution Efficiency and Chlorine Evolution Efficiency for Electrocatalytic Properties of MnO₂-based Electrodes in Seawater

Abstract

To improve both oxygen evolution efficiency and stability at high temperatures, Mn, Mn+Mo, Mn+Mo+V, and Mn+Fe+V oxide electrodes were prepared on a Ti substrate, with an intermediate layer of IrO₂, by an anodic deposition method. The crystal structure, surface morphology, pore size distribution, specific surface area, and voltammetric charge were then characterized for each electrode. The results demonstrated that for Mn-O electrodes, the preferential orientation of the (100) crystal plane and the mesopore structure played negative roles in the oxygen evolution reaction. On the basis of the electrocatalytic properties of MnO₂- based electrodes in seawater, the outer surface voltammetric charge at a scan rate of 500 mV·s⁻¹ was shown to effectively indicate whether oxygen evolution reactions were preferred over chlorine evolution reactions. The Mn-O electrode exhibited oxygen evolution efficiency of only 47.27%, whereas the Mn+Mo, Mn+Mo+V and Mn+Fe+V oxide electrodes displayed oxygen evolution efficiency of nearly 100%. This means that adding Mo, V, and Fe elements to the electrode can improve its crystal structure and morphology as well as further enhancing its oxygen evolution efficiency.

Keywords

electrodeposition / MnO₂-based electrodes / oxygen evolution reaction / seawater electrolysis