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

Abstract 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 PdH x @Pt by incorporating LH allows more surface vacancy Pt sites to increase the surface H coverage. The inverse dehydrogenation process makes PdH x as an H reservoir, providing LH migrates to the surface of Pt and participates in the HOR. Meanwhile, the formation of PdH x 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 PdH x @Pt. Moreover, this dynamic catalysis mechanism would open up the catalysts scope for hydrogen electro‐catalysis.