Nanoporous Ag–Mn Alloy Electrocatalysts via Dealloying for Enhanced Oxygen Reduction Reaction in Zinc-Air Batteries

Zinc-air batteries (ZABs) are an emerging energy technology that is environmentally friendly and has a high theoretical energy density, but their commercial application is limited by the oxygen reduction reaction (ORR). Silver-based nanocatalysts can effectively improve the ORR performance. In this paper, a nanoporous Ag–Mn (NP-AM) electrocatalyst with bicontinuous ligaments was prepared by a combination of the melt-spinning technique and dealloying method. Theoretical calculations show that Mn-doped Ag(111) indicates a shift of the d-band center toward the Fermi energy level, which improves the adsorption energy of the OOH and thus reduces the overpotential of the decision step in the ORR process. Among them, the electrocatalyst NP-AM-5 reached a half-wave potential of 0.81 V (vs reversible hydrogen electrode (RHE)) with a limiting current density of −5.63 mA cm–2. Tests showed that its ORR process almost completely undergoes 4e– transfer with higher conversion efficiency and also exhibits better long-term stability in comparison to commercial Pt/C electrocatalysts. When used as the cathode of a zinc-air battery, the maximum power density reaches 140 mW cm–2. The discharge voltage can be maintained at about 1.2 V for a long period of time by discharging at a constant current of 10 mA cm–2, and the specific capacity is calculated to be 724 mAh g–1.