Tailoring Pt-Support Interactions via Mn-Nx Coordination for Enhanced Phosphoric Acid Tolerance in HT-PEMFC Cathodes

Abstract

Phosphoric acid (PA) diffused from membrane to the cathode catalyst layer and its irreversible binding to Pt sites critically deteriorate 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 and electronic modulation to mitigate PA poisoning. The Mn-N x moieties function as electron acceptors, inducing charge transfer from Pt nanoparticles to Mn-N x sites and downshifting the Pt d-band center, thereby weakening the adsorption strength of PA species. As a result, Pt@Mn-N-C exhibits a half-wave potential (E 1/2 ) of 0.828 V, superior to 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 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.