Dual modulation of electronic and crystalline structures in PtCo alloys for high-performance fuel cells

Abstract

Although transition metal alloying boosts catalytic performance, it inevitably compromises stability through non-noble metal leaching. Therefore, breaking the intrinsic activity–stability trade-off in platinum-alloy catalysts is pivotal for advancing proton exchange membrane fuel cells. Herein, we demonstrate that in situ nitrogen doping effectively breaks this dilemma in ordered L1₀-PtCo alloys via concurrent electronic and crystalline modulation. The incorporated nitrogen species not only introduce additional lattice strain but also induce distinct p–d orbital hybridization. This orchestrated regulation simultaneously optimizes the Pt d-band center for enhanced oxygen reduction reaction kinetics, while concurrently elevating the vacancy formation energies of both Pt and Co atoms, thereby effectively suppressing their dissolution. In rotating disk electrode tests, the developed DM-L1₀-PtCoN catalyst exhibits a mass activity four times that of the Pt/C catalyst. Under the demanding condition of an ultralow total Pt loading of 0.1 mg_Pt cm⁻², this catalyst demonstrates excellent PEMFC performance. At an operating potential of 0.6 V, the catalyst achieves a current density of 1.75 A cm⁻² under a H₂–air atmosphere, with a peak power density of 1.42 W cm⁻². After 30 000 cycles of accelerated stress testing, the catalyst retains 72.2% of its initial power density. This work reveals that the synergistic engineering of both electronic and crystal structures in ordered L1₀-PtCo alloys is the key to breaking the longstanding activity–stability trade-off, paving the way for the rational design of next-generation, durable platinum fuel cell catalysts.