Robust p-d Orbital Coupling in PtCoIn@Pt Core–Shell Catalysts for Durable Proton Exchange Membrane Fuel Cells

Abstract

Pt-based catalysts are playing increasingly important roles in fuel cells owing to their high catalytic activity. However, harsh electrocatalytic conditions often trigger atomic migration and dissolution in these catalysts, causing rapid performance deterioration. Here, a novel L1₀-PtCoIn@Pt core–shell catalyst is introduced, where indium (In) is incorporated into a PtCo matrix. This integration promotes p–d orbital coupling, optimizing the electronic structure of Pt and causing additional lattice strain within PtCo. Impressively, L1₀-PtCoIn@Pt exhibits remarkable activity and durability, with only a 5.1% reduction in mass activity (MA) after 120 000 potential cycles. In H₂-O₂ fuel cells, this cathode achieves a peak power density of 1.99 W cm⁻² and maintains a high MA of 0.73 A mg_Pt⁻¹ at 0.9 V. After enduring 60 000 square wave potential cycles, the catalyst maintains its initial MA and sustains the cell voltage at 0.8 A cm⁻², exceeding the U.S. Department of Energy (DOE) 2025 targets. Theoretical studies highlight the enhancements originating from the modulated electronic structures and shifted d-band center of Pt induced by In doping and increased vacancy formation energies in Pt and Co atoms, affirming the catalyst's superior durability.