Stabilization of Co oxide during oxygen evolution in alkaline media by the introduction of Mn oxide

TL;DR

This study demonstrates that adding Mn oxide to Co oxide enhances the stability and activity of catalysts during oxygen evolution in alkaline media, addressing durability issues in electrocatalyst design.

Contribution

The paper introduces a novel approach of Mn addition to Co oxide to improve catalyst stability and activity during OER in alkaline solutions.

Findings

Mn addition stabilizes Co oxide during OER cycling

Mn-doped Co oxide shows increased activity over time

XAS confirms oxidation state changes supporting stability

Abstract

Improving the stability of electrocatalysts for the oxygen evolution reaction (OER) through materials design has received less attention than improving their catalytic activity. We explored the effect of Mn addition to a cobalt oxide for stabilizing the catalyst by comparing Na-containing CoOx and (Co0.7Mn0.3)Ox films electrodeposited in alkaline solution. The obtained disordered films were classified as layered oxides using X-ray absorption spectroscopy (XAS). The CoOx films showed a constant decrease in the catalytic activity during cycling, confirmed by oxygen detection, while that of (Co0.7Mn0.3)Ox slightly increased as measured by electrochemical metrics. These trends were rationalized based on XAS analysis of the metal oxidation states, which were Co2.8+ and Mn3.7+ near the surface after cycling. Thus, adding Mn to CoOx successfully stabilized the catalyst material and its activity during OER cycling. The development of stabilization approaches is essential to extend the durability of OER catalysts.