Ag-Induced Electronic Structure Modulation in N-Doped Porous Carbon for Enhanced Bifunctional Oxygen Electrocatalysis

Nitrogen-doped porous carbon (Nx-C) derived from zeolitic imidazolate framework-8 (ZIF-8) was employed as a conductive support for Ag nanoparticles to develop a bifunctional oxygen electrocatalyst for rechargeable zinc-air batteries. Pyrolysis of ZIF-8 at 1000 °C produced porous Nx-C with a large specific surface area of 445.21 m2 g-1, while subsequent Ag deposition yielded Ag-Nx-C with a surface area of 112.89 m2 g-1. The optimized Ag-Nx-C catalyst exhibited current densities of 241.5 mA cm-2 at 0.5 V for the oxygen reduction reaction (ORR) and 148.2 mA cm-2 at 2.4 V for the oxygen evolution reaction (OER) (vs Zn/Zn2+). Density functional theory calculations reveal that Ag incorporation shifts the C p-band and Ag d-band centers toward the Fermi level, strengthening interfacial electronic interactions and improving the adsorption energetics of oxygen-containing intermediates. The combined experimental and theoretical results demonstrate an effective electronic structure engineering strategy for high-performance bifunctional oxygen electrocatalysts.