Low-Loading Pt nanoparticles supported by Fe-N-C rich in FeNX sites with strong electronic interaction for high oxygen reduction performance

Abstract

Reducing the Pt loading and enhancing Oxygen Reduction Reaction (ORR) activity is a promising approach to promote the large-scale application of fuel cells. In this study, we successfully constructed an efficient catalyst with low loading of Pt by anchoring platinum nanoparticles (Pt NPs) onto nitrogen-doped carbon support enriched with FeN_X active sites via a solvothermal method. XPS analysis demonstrated that the introduction of urea increased the nitrogen content of the support, promoted the formation of FeN_X sites, and revealed strong electron transfer at the interface between Pt and the support. DFT calculations further validated that FeN_X sites facilitate electron transfer, reduce the d-band center of Pt, and promote the desorption process of *OH intermediates. Furthermore, the differential charge density visually demonstrated the electron redistribution at the Pt/FeN_X interface. This strong electronic interaction endowed the catalyst at a low Pt loading (10 wt%) with a half-wave potential (E_1/2) of 0.887 V, exceeding commercial Pt/C (0.849 V) by 38 mV. Meanwhile, 94 % of initial activity can be maintained after a chronoamperometric test of 10 h, outperforming commercial Pt/C (89 %). This work reveals the Pt/FeN_X interaction and provides a novel strategy for designing high-performance low-Pt catalysts.