Pt-Based Rare Earth Alloy as Efficient and Robust Electrocatalyst for High-Temperature Proton Exchange Membrane Fuel Cells

Abstract

High-temperature proton exchange membrane fuel cells (HT-PEMFCs) are crucial in future energy systems. However, the activity and stability of the electrocatalysts are severely restricted by high temperature and phosphoric acid poisoning. Herein, PtCe alloy as oxygen reduction reaction (ORR) electrocatalyst for HT-PEMFCs exhibits fantastic performance. Ce can increase the electronic density of Pt, weakening phosphoric acid poisoning and improving ORR activity. The optimized electronic structure can also reduce the dipole effect between Pt and O, which suppresses the irreversible oxidation of Pt. Additionally, the dramatically negative heat of formation in PtCe catalyst brings high kinetic barrier of metal diffusion and dissolution. With this electrocatalyst, the HT-PEMFCs show a preeminent peak power of 605 mW cm^-2 with 0.3 mg_Pt cm^-2 . After 30000 cycles of accelerated stability test, the peak power density only decreases by 31.6%, achieving the goal of Department of Energy in 2020 (<40% loss).

Keywords: PtCe alloy; high-temperature proton exchange membrane fuel cells; oxygen reduction reaction; phosphoric acid poisoning.