Spinel MnCo2O4 nanoparticles cross-linked with two-dimensional porous carbon nanosheets as a high-efficiency oxygen reduction electrocatalyst

Abstract

Catalysts for the oxygen reduction reaction (ORR) play an important role in fuel cells. Alternative non-precious metal catalysts with comparable ORR activity to Pt-based catalysts are highly desirable for the development of fuel cells. In this work, we report for the first time a spinel MnCo2O4/C ORR catalyst consisting of uniform MnCo2O4 nanoparticles cross-linked with two-dimensional (2D) porous carbon nanosheets (abbreviated as porous MnCo2O4/C nanosheets), in which glucose is used as the carbon source and NaCl as the template. The obtained porous MnCo2O4/C nanosheets present the combined properties of an interconnected porous architecture and a large surface area (175.3 m2·g-1), as well as good electrical conductivity (1.15 × 102 S·cm-1). Thus, the as-prepared MnCo2O4/C nanosheets efficiently facilitate electrolyte diffusion and offer an expedite transport path for reactants and electrons during the ORR. As a result, the as-prepared porous MnCo2O4/C nanosheet catalyst exhibits enhanced ORR activity with a higher onset potential and current density than those of its counterparts, including pure MnCo2O4, carbon nanosheets, and Vulcan XC-72R carbon. More importantly, the porous MnCo2O4/C nanosheets exhibit a comparable electrocatalytic activity but superior stability and tolerance toward methanol crossover effects than a high-performance Pt/C catalyst in alkaline medium. The synthetic strategy outlined here can be extended to other nonprecious metal catalysts for application in electrochemical energy conversion.