Promotion mechanism of PtCo intermetallic ordered alloys in oxygen reduction reaction and its application in fuel cells
Wei‐Cheng Xu, Zhiming Zhang, Cong‐Hua Yang, Kuangmin Zhao, Yucheng Wang, Na Tian, Zhi‐You Zhou, Shi‐Gang Sun
Abstract
Ordered intermetallic Pt-M alloys are promising as next-generation low-Pt catalysts for oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs) due to the high ORR activity and excellent long-term stability. However, the mechanism behind the enhancement of ORR activity by ordering mostly comes from theoretical calculations, and experimental evidence is very lacking. Herein, we prepared a surface Pt-rich PtCo ordered alloy of about 3 nm in size, which exhibited high ORR catalytic activity, achieving impressive performance of 1.4 W cm−2 @ 0.6 V in H2-air fuel cell and mass activity of 0.62 A mgPt-1 @ 0.9 ViR-free in H2-O2 fuel cell. The key ORR intermediate, adsorbed *O2, was successfully detected by electrochemical in situ infrared spectroscopy. Compared with Pt and disordered PtCo, the ordered PtCo alloy has optimal adsorption interaction with *O2, accelerating the ORR kinetics.