Assembly of hollow mesoporous nanoarchitectures composed of ultrafine Mo2C nanoparticles on N-doped carbon nanosheets for efficient electrocatalytic reduction of oxygen
A simple method is developed to assemble Mo 2 C nanocrystals on the surfaces of hollow, highly conductive mesoporous nanoparticles. Diblock copolymer (PS-b-PEO) micelles are used as templates to assist in the fast complexation of molybdate (MoO 4 2- ) and polydopamine (PDA) precursors to make hollow precursor MoO 4 2- /PDA/PS-b-PEO particles. Then these particles are carbonized to generate mesoporous N-doped carbon nanosheets riddled with ultrafine molybdenum carbide (Mo 2 C) nanoparticles (MMo 2 C/NCS). An N-doped carbon matrix serves as an electron conductor and helps to prevent the aggregation of the Mo 2 C nanoparticles. The Mo 2 C nanoparticles in turn enhance the catalytic performance for the oxygen reduction reaction (ORR). The unique mesoporous 2D nanosheet and its derived 3D hollow structure expose numerous active catalytic sites while enabling free diffusion of the electrolyte and mass transfer. Based on these properties, MMo 2 C/NCS show enhanced catalytic activity for the ORR.