Nonprecious Co-N-P-C@Mo2TiC2 Catalyst for the High-Performance Oxygen Reduction Reaction in PEMFCs

The oxygen reduction reaction (ORR) has been considered as the rate-limiting step in proton-exchange membrane fuel cells. Therefore, noble metals such as Pt are used as catalysts, which restricts cost reduction. Nonprecious metals have attracted much attention as ORR catalysts, but the low catalytic activity and stability are still challenges associated with their use. Transitionmetal/nitrogen/carbon (M-N-C) materials are widely used due to their low cost and relatively high activity. Electronic, compositional, and geometric effects offered by the metal-support interaction could enhance the catalytic activity and stability. In this study, MXene (Mo2TiC2), with high corrosion resistance and excellent electrical conductivity, is used as a support for Co-N-P-C to construct the Co-N-P-C@Mo2TiC2 catalyst. The half-wave potential of Co-N-P-C@Mo2TiC2 reaches 0.78 V, and the peak power density based on the catalyst reaches 880 mV cm-2. CoN-P-C@Mo2TiC2 exhibits excellent stability in both ORR (only 18 mV loss after 10 000 cycles) and single-cell tests.