Mo2C Hollow Nanospheres with Co-Nx Sites in N-Doped Carbon Heterostructures as Trifunctional Electrocatalysts for Electrochemical Energy Conversion

Developing highly efficient and durable trifunctional electrocatalysts is essential for advancing technologies related to water splitting, oxygen reduction, and hydrogen storage, which are critical for energy conversion and storage. In this study, we encapsulated Co-MOFs on the surface of Mo₂C hollow spheres and achieved the Co@NC/Mo₂C composite material through high-temperature annealing. In the optimal catalyst, Co@NC/Mo₂C-0.1, Co@NC nanosheets were uniformly distributed on the Mo₂C hollow spheres, and the BET surface area was well maintained. Compared to Co nanoparticles, Co-Nx in Co@NC/Mo₂C-0.1 exhibited a greater modulation effect on the electronic structure of Mo₂C. Density functional theory (DFT) calculations showed that the Co@NC/Mo₂C heterostructure effectively lowered the energy barrier for the hydrogen evolution reaction (HER) on Mo₂C and enhanced the performance of the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) through electronic coupling. Specifically, for Co@NC/Mo₂C-0.1, at a current density of 10 mA cm^–2, the half-wave potential for ORR was 0.86 V, the overpotential for OER was 349 mV, and the overpotential for HER was 158 mV. Additionally, this catalyst exhibited exceptional stability across all three reactions, making it an ideal candidate for sustainable energy technologies.