Oxygen‐Driven Reconstruction Activates Quasi‐Single Pd Sites in Hollow PdAg Nanotubes for Zinc–Air and Fuel Cells

Abstract Here, a template‐engaged galvanic replacement strategy is developed to construct hollow PdAg alloy nanotubes, where interfacial oxygen drives surface reconstruction and stabilizes quasi‐single Pd active sites. The interplay of atomic‐scale characterizations and theoretical calculations reveals that the oxygen‐induced atomic rearrangement downshifts the Pd d ‐band center, optimizes the adsorption‐desorption energetics of ORR intermediates, and lowers the energy barrier for ^* OH desorption. The optimized Pd _0.30 @Ag catalyst achieves an onset potential of 0.951 V and a half‐wave potential of 0.868 V in alkaline media, surpassing commercial Pt/C even at an ultra‐low Pd loading (3 wt.%). Furthermore, Pd _0.30 @Ag‐based electrodes deliver outstanding performance in both zinc‐air batteries (ZABs) and anion‐exchange membrane fuel cells (AEMFCs), demonstrating high power densities, excellent cycling stability, and strong potential for scalable platinum‐free energy conversion devices. This work provides a general strategy for engineering interface‐confined active sites through surface reconstruction, offering new insights into the rational design of next‐generation electrocatalysts.