Facet-evolution growth of Mn3O4@CoxMn3-xO4 electrocatalysts on Ni foam towards efficient oxygen evolution reaction.

Graphical abstract This paper describes core-shell cobalt-manganese oxides with specific morphologies and oxygen vacancies for electrochemical water oxidation. Highlights • A new preparation method with facet modulation of Mn@CoMnO nanoparticles is developed. • Octahedral truncated octahedral, and cubic structures of nanoparticles NPs are successfully synthesized. • The correlation between structure and electrochemical water oxidation properties is proposed. • Exposed octahedral active cation and enhanced charge-transfer ability are important. Abstract Developing efficient and stable non-noble electrocatalysts for oxygen evolution reaction (OER) is one of the promising and challenging issues. This paper describes an approach to prepare core-shell cobalt-manganese oxides with specific morphologies and oxygen vacancies. Via a facile seed growth method, facets evolution is achieved during the formation of core-shell structure. Benefited from optimized surface environment, oxygen vacancy-enriched octahedral cobalt-manganese oxides supported on Ni foam exhibited relatively low overpotential of 284 mV at the current density of 10 mA cm−2 and diminutive tafel slope of 73.1 mV dec−1 as well as long-term stability. This work successfully unveils a method for facet-modulation of core-shell metal oxides as efficient electrochemical OER catalysts. [ABSTRACT FROM AUTHOR]