Enhanced phosphoric acid tolerance and intrinsic activity of ordered platinum-zinc alloy catalysts for oxygen reduction reaction.

High-temperature proton exchange membrane fuel cells (HT-PEMFCs) offer significant advantages in energy conversion efficiency but face severe challenges from phosphoric acid (PA) poisoning, which deactivates platinum (Pt)-based oxygen reduction reaction (ORR) catalysts. This study presents a dual strategy combining structural ordering and electrochemical potential cycling to enhance the intrinsic catalytic activity and PA tolerance of platinum-zinc (PtZn) alloy catalysts. Ordered PtZn (L1-PtZn) alloy electrocatalysts synthesized through thermal annealing demonstrated enhanced ORR performance, achieving a mass activity of 0.42 A mg-1Pt, surpassing the A1-PtZn (0.28 A·mg-1Pt) and commercial Pt/C electrocatalysts (0.17 A·mg-1Pt). Transmission electron microscopy (TEM) and X-ray diffraction (XRD) and analyses revealed the structural advantages of L1-PtZn, including optimized lattice strain and reduced surface Zn obstacle. Single-cell tests confirmed its superior power density of 411 mW·cm, outperforming disordered alloys and commercial catalysts. Under phosphoric acid exposure, the L1-PtZn catalyst demonstrated exceptional tolerance and exhibiting minimal Pt and Zn dissolution during accelerated degradation tests. The remarkable stability and enhanced activity are attributed to the inherent atomic ordering and surface reconstruction mechanisms of L1-PtZn. These findings underscore the potential of ordered PtZn alloys as next-generation cathode catalysts for HT-PEMFCs, addressing critical challenges of PA tolerance and long-term stability.