Tailoring Pt–support interactions via Mn–Nx coordination for enhanced phosphoric acid tolerance in HT-PEMFC cathodes

Abstract

Phosphoric acid (PA) diffuses from the membrane to the cathode catalyst layer and its irreversible binding to Pt sites critically deteriorates the oxygen reduction reaction (ORR) kinetics and durability of high-temperature proton exchange membrane fuel cells (HT-PEMFCs). Herein, we develop a Mn–N_x coordinated carbon-supported Pt catalyst (Pt@Mn–N–C) that integrates strong metal–support interaction (SMSI) and electronic modulation to mitigate PA poisoning. The Mn–N_x moieties act as electron acceptors, inducing electron transfer from Pt nanoparticles to Mn–N_x sites, which downshifts the Pt d-band center and weakens PA adsorption on Pt sites. As a result, Pt@Mn–N–C exhibits a half-wave potential (E_1/2) of 0.828 V, superior to that of commercial Pt/C (0.786 V), and retains nearly intact ORR activity after 10 000 potential cycles in PA-containing electrolyte, while Pt/C suffers from a 40 mV loss. When applied in HT-PEMFCs, Pt@Mn–N–C delivers 20% higher peak power density and stable performance for 100 h at 0.5 A cm⁻². This work provides a viable interfacial engineering strategy to suppress PA poisoning and enhance catalyst durability, advancing the practical application of HT-PEMFC technology.