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

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.