Dealloying-engineered nanoporous Ag-Pt solid-solution alloys with synergistic dual sites for efficient oxygen...

The development of high-performance and durable alloy electrocatalysts is essential for advancing oxygen reduction reaction (ORR) efficiency. In this work, nanoporous alloys with varying Ag/Pt ratios were constructed via a dealloying-based strategy. The phase and microstructure of alloys were found to depend strongly on the Ag/Pt ratio, and their structure-activity relationship was systematically investigated. The D-Ag_xPt_1-x alloys (x = 0.75, 0.5 and 0.25 at. %) containing both Ag and Pt exhibited excellent ORR activity, with half-wave potentials (E_1/2) of 0.815-0.818 V vs. RHE and Tafel slopes of 69-91 mV dec^-1, outperforming the single-metal counterparts (x = 0 or 1 at. %). The D-Ag_0.75Pt_0.25 catalyst possesses excellent ORR catalytic activity and durability in 0.1 M HClO₄ electrolyte. This enhanced performance is closely linked to the formation of a nanoporous solid-solution alloy structure. When applied as a cathode catalyst in a zinc-air battery (ZAB), the D-Ag_0.75Pt_0.25 electrode delivered a peak power density of 153.4 mW cm^-2 and a specific capacity of 795 mAh g_Zn^-1, along with remarkable stability over 350 h of charge/discharge cycling. It also shows application potential as a flexible ZAB cathode catalyst. Theoretical calculations revealed that the D-Ag_0.75Pt_0.25 catalyst features cooperative Ag-Pt dual sites with clear synergistic effects. The residual non-noble metals (Al, Mn, Ni, Cu) act as electron donors, transferring charge to Ag and Pt and inducing charge redistribution, which optimizes the d-band center and e_g occupancy. These electronic adjustments lower the energy barrier of the rate-determining step, thereby enhancing ORR activity. This work not only demonstrates a feasible route for constructing efficient Ag-Pt dual-site catalysts via dealloying, but also provides mechanistic insights that can guide the design of advanced catalysts for energy storage and conversion applications.