Functionalized nitrogen doping induced manganese oxyhydroxide rooted in manganese sesquioxide rod for robust oxygen reduction electrocatalysis

Abstract

The rational synthesis of hybrid catalysts with diverse electrocatalytically active components for robust oxygen reduction reaction (ORR) is highly desirable for the development of sustainable metal-air batteries. By using melamine as nitrogen and hydrogen precursors, herein, melamine pyrolysis-induced functionalized nitrogen doping was adopted for the construction of nitrogen doped manganese oxides (N-MnOx Rs), which consists of manganese oxyhydroxide (MnOOH) rooted in manganese sesquioxide (Mn2O3) rod, as a robust ORR electrocatalyst. Systematic studies have found that a suitable mass ratio of melamine to β-MnO2 rods is necessary for the formation of electrocatalytically MnOOH and Mn2O3. The representative N-MnOx Rs exhibits the nano structure consisting of interconnected nonorods, nanowires, and nanoparticles, which not only increases the exposure of more active sites but also enhances microstructure stability. Moreover, the nitrogen doping creates high content of oxygen vacancies, which accelerates electron transmission/transfer of N-MnOx Rs. As a result, the optimal N-MnOx Rs exhibits impressive ORR catalytic performance in a homemade ZAB. The N-MnOx Rs driven ZAB (176.6 mW cm-2; 811 mAh g-1) delivers a high peak power density and large discharging capacitance comparable to Pt/C driven one (178.1 mW cm-2; 800 mAh g-1), displaying a promising application potential. This work provides a functionalized nitrogen doping strategy for rational construction of robust hybrid electrocatalysts for energy conversion.