Enhancing the catalytic activityof Ru metal in the hydrogen oxidationreaction (HOR) potential range, improving the insufficient activityof Ru caused by its oxophilicity, is of great significance for reducingthe cost of anion exchange membrane fuel cells (AEMFCs). Here, weuse Ru grown on Au@Pd as a model system to understand the underlyingmechanism for activity improvement by combining direct in situ surface-enhancedRaman spectroscopy (SERS) evidence of the catalytic reaction intermediate(OHad) with in situ X-ray diffraction (XRD), electrochemicalcharacterization, as well as DFT calculations. The results showedthat the Au@Pd@Ru nanocatalyst utilizes the hydrogen storage capacityof the Pd interlayer to "temporarily" store the activatedhydrogen enriched at the interface, which spontaneously overflowsat the "hydrogen-deficient interface" to react withOH(ad) adsorbed on Ru. It is the essential reason for theenhanced catalytic activity of Ru at anodic potential. This work deepensour understanding of the HOR mechanism and provides new ideas forthe rational design of advanced electrocatalysts.
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