Ordered Ag@Pd alloy supported on Ti4O7 by ascorbic acid-assisted galvanic replacement for efficient oxygen reduction

Core-shell catalysts have been extensively researched in enhancing the activity of oxygen reduction reaction (ORR) by modifying bimetallic electrons. However, the conventional methods for synthesizing core-shell structures are not appropriate for supported catalysts. Here, we present a strategy to support ordered Ag@Pd core-shell structures on the Ti 4 O 7 surface by ascorbic acid-assisted galvanic replacement (GR). The addition of appropriate amounts of Pd precursors during GR plays a crucial role in the morphology and activity of the ordered Ag@Pd/Ti 4 O 7 . Ordered Ag@Pd/Ti 4 O 7 exhibits a half-wave potential of 0.895 V and mass activity of 1.22 A mg Pd -1 at 0.9 V, where the latter is approximately 13.7 times higher than that of 20% Pt/C. Excitingly, the zinc-air battery with an ordered Ag@Pd/Ti 4 O 7 catalyst as the cathode shows a maximum power density of 174 mW cm -2 . The ordered characteristics of the Ag@Pd alloy and its strong electron transfer with the corrosion-resistant Ti 4 O 7 effectively inhibit the oxidation of Ag, thus improving the catalytic activity and stability. The ingenious combination of ascorbic acid with GR provides a feasible mechanism for the synthesis of ordered bimetallic core-shell structure on oxide surfaces. • A new synthetic strategy was proposed to prepare ordered core-shell structures supported on oxides by ascorbic acid assisted galvanic replacement. • The addition of appropriate amounts of Pd precursors in the GR exhibits important effects on the morphology and activity of ordered Ag@Pd/Ti 4 O 7 . • The ordered characteristic of the Ag@Pd and the strong electron transfer with corrosion-resistant Ti 4 O 7 improve the catalytic ORR activity and stability.