Lattice Hydrogen Boosts CO Tolerance of Pd Anode Catalysts in High-Temperature Proton Exchange Membrane Fuel Cells

Abstract

High-temperature proton exchange membrane fuel cells (HT-PEMFCs) demonstrate crude hydrogen can be a cost-effective fuel source. However, the performance of HT-PEMFCs is hindered by challenges such as high-concentration CO poisoning and preferential adsorption of H₃PO₄ on electrocatalysts. This study explores the performance of Pt group metals as anode catalysts, specifically focusing on hydrogen oxidation reaction (HOR) activity, H₃PO₄ tolerance, and CO tolerance under operational conditions in HT-PEMFCs. The results reveal that all Pt-group catalysts significantly improve HOR activity with increasing reaction temperature. Notably, Pd-based catalysts demonstrate superior H₃PO₄ tolerance and CO tolerance. HT-PEMFCs using Pd/C as the anode catalyst maintain the highest output power density, achieving a remarkable 6.4-fold performance compared to Pt/C catalysts and superior stability in the presence of 3%–10% CO in H₂. Both experimental and theoretical investigations have consistently demonstrated that Pd possesses the weakest CO adsorption energy, the existence of CO in crude H₂ in HT-PEMFCs inhibits hydrogen overflow from the lattice interstitial space of Pd, and the trapped lattice hydrogen further promotes the desorption of CO. This research contributes to the advancement of direct utilizing industrial crude hydrogen as a fuel for HT-PEMFCs and offers invaluable insights into reactions involving CO.