High-temperature annealing improves Pt utilization of proton exchange membrane fuel cell cathode catalysts

High-temperature annealing is widely recognized as an effective way to improve the durability of Pt/C cathode catalysts used in proton exchange membrane fuel cells (PEMFCs), yet systematic studies on its effects on PEMFC performance are still lacking. Herein, we explore the effect of high-temperature annealing on the PEMFC performance, based on a thorough comparative analysis of Pt/C catalysts annealed at temperatures ranging from 500–900°C. Our results reveal that high-temperature annealing not only enhances the catalyst durability but also substantially increases Pt utilization, which in turn drives the increase in mass activity and the enhancement of low-current-density performance. Based on an array of electrochemical and physical characterization results, we infer that the increased utilization of Pt might stem from nanoparticle migration induced by high-temperature annealing, leading to closer proximity between Pt nanoparticles and ionomers. This reduced distance potentially enhances the accessibility of protons to the Pt nanoparticles, thereby improving the Pt utilization.