Ultrathin Ni–N–C layer modified Pt–Ni alloy nanoparticle catalysts for enhanced oxygen reduction.

Accelerating the commercialization of fuel cells requires the development of Pt-based alloy cathode catalysts with high ORR operation, low price, and excellent reliability. However, it is a challenging task to fabricate uniformly dispersed, low-loaded, and small-sized Pt-based alloy catalysts to resolve the contradiction between activity and stability. Here, sub-3 nm N-doped PtNi nanoparticles (NPs) are synthesized as high-performance PEMFC cathode catalysts. PtNi/Ni-NC exhibits excellent electrocatalytic activity (0.51 A mg Pt −1@0.8 V and peak power density of 328 mW cm−2) as well as stability (only 15 mV loss in E 1/2 after 5000 cycles of ADT tests) in oxygen reduction reaction (ORR). The experimental results show that N doping modulates the electronic structure around Pt and optimizes the lattice compressive strain, thus attenuating the adsorption of oxygen intermediates on the surface Pt and enhancing the ORR activity. Meanwhile, the encapsulation of PtNi NPs by the constructed ultrathin Ni–N–C layer accounts for the improved stability. This work offers a novel perspective f for raising the stability and catalytic performance of Pt-based catalysts. • N doping provides optimum compressive strain on the dominating surface of PtNi (111). • Constructed ultrathin Ni–N–C layers can encapsulate small PtNi NPs and strengthen their targeting. • PtNi/Ni-NC with sub-3 nm can be used as an efficient ORR catalyst for MEA. [ABSTRACT FROM AUTHOR]