Nanoconfined nitrogen-doped carbon-coated MnO nanoparticles in graphene enabling high performance for lithium-ion batteries and oxygen reduction reaction

Abstract

To tackle the issues of inferior cycling stability and low conductivity for MnO as an anode material for lithium ion batteries (LIBs) and as a catalyst for oxygen reduction reaction (ORR), a facile and effective strategy is explored to confine N-doped carbon-coated MnO nanoparticles in a conductive graphene matrix. The synthesis of the GMNCs involves the two-step coating of Mn₃O₄ nanocrystals with polydopamine and graphene, followed by heat treatment to form the GNS@MnO@N-doped carbon composites (GMNCs). When evaluated as anode materials for LIBs, the as-prepared GMNCs exhibit an improved cycling stability (754.3 mA h g⁻¹ after 350 cycles at 0.1 A g⁻¹) compared to carbon-coated MnO and pure Mn₃O₄ due to the double carbon coating design. When evaluated as catalysts for ORR, the as-prepared GMNCs exhibit higher electrocatalytic activity than that of pure Mn₃O₄ and MnO catalysts, and superior stability to a commercial Pt/C catalyst due to the synergetic effect between the MnO and N-doped double carbon coating. The optimum design of the unique nanostructures with the synergetic effect provides a new route to design advanced materials as electrode/catalysts for energy conversion and storage.