Improving Alkaline Hydrogen Oxidation through Dynamic Lattice Hydrogen Migration in Pd@Pt Core‐Shell Electrocatalysts

• Published in: Angewandte Chemie 2024-01, Vol.136 (5), p.n/a
• Main Authors: Zhao, Tonghui, Li, Mengting, Xiao, Dongdong, Yang, Xiaoju, An, Lulu, Deng, Zhiping, Shen, Tao, Gong, Mingxing, Chen, Yi, Liu, Hongfang, Feng, Ligang, Yang, Xuan, Li, Li, Wang, Deli
• Format: Article
• Language: English
• Subjects: Anion Exchange Membrane Fuel Cells; Catalysis; Catalysts; Chemistry; Dehydrogenation; Dynamic Mechanism; Electrocatalysts; Electrochemistry; Hydrogen; Hydrogen Oxidation Reaction; Intermediates; Intermediates Migration; Oxidation; Palladium; Platinum; Polarization-Driven Lattice Hydrogen
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.202315148

Tracking the trajectory of hydrogen intermediates during hydrogen electro‐catalysis is beneficial for designing synergetic multi‐component catalysts with division of chemical labor. Herein, we demonstrate a novel dynamic lattice hydrogen (LH) migration mechanism that leads to two orders of magnitude increase in the alkaline hydrogen oxidation reaction (HOR) activity on Pd@Pt over pure Pd, even ≈31.8 times mass activity enhancement than commercial Pt. Specifically, the polarization‐driven electrochemical hydrogenation process from Pd@Pt to PdHx@Pt by incorporating LH allows more surface vacancy Pt sites to increase the surface H coverage. The inverse dehydrogenation process makes PdHx as an H reservoir, providing LH migrates to the surface of Pt and participates in the HOR. Meanwhile, the formation of PdHx induces electronic effect, lowering the energy barrier of rate‐determining Volmer step, thus resulting in the HOR kinetics on Pd@Pt being proportional to the LH concentration in the in situ formed PdHx@Pt. Moreover, this dynamic catalysis mechanism would open up the catalysts scope for hydrogen electro‐catalysis. A dynamic lattice hydrogen (LH) migration mechanism is proposed to understand the two orders of magnitude enhancement of the kinetics for alkaline hydrogen oxidation reaction (HOR) on Pd@Pt core–shell model than pure Pd. Surface Pt atoms promote the H2 dissociation and the adsorbed hydrogen (Had) incorporation into the Pd lattice. Internal PdHx (PdHab) act as a hydrogen reservoir, providing LH to migrate to the surface Pt and combine with OH− to form water.