Bimetallic self-supported AuCu alloy aerogel with abundant diffusion channels for regulating oxygen reduction reaction by electronic structure modulation for zinc-air battery application

The Noble Gold (Au) has great potential for application in the field of electrocatalysis due to its excellent catalytic activity and stability. However, the high cost, scarcity, and the too-weak binding strength, greatly limit its wide application in the oxygen reduction reaction (ORR) field. Herein, we have developed a low-cost and mild reducing agent for Au₂Cu alloy aerogel electrocatalyst fabrication by self-assembly combined with a freeze-drying technique. The obtained aerogel exhibits a “pearl-like” hierarchical porous structure with abundant diffusion channels, which benefits O₂ diffusion and full exposure of active sites. It is worth mentioning that the optimized Au₂Cu alloy aerogel electrocatalyst exhibits a large half-wave potential of 0.85 V vs. RHE, a large kinetic current density of 5.3 mA·cm⁻², excellent durability, and methanol poisoning resistance. The Koutecky-Levich equation and the Rotating Ring-Disk Electrode (RRDE) test further verified the four proton-electron coupling transfer process. It is impressive that the Au₂Cu alloy aerogel-based zinc-air batteries exhibit a high open circuit potential (1.48 V), power density (211 mW·cm⁻²), and almost no attenuation of energy efficiency after a 160 h charge–discharge cycle. As revealed by the d-band center theory, the partially oxidized Au₂Cu alloy aerogel promotes the band center to move away from the Fermi level, and the anti-bond energy level of the adsorbate decreases with more electrons occupied, therefore decreasing the binding strength of the adsorbed *OOH intermediate, which is responsible for the enhanced ORR activity. This work opens up an effective method for exploring aerogel-based green electrocatalysts in energy development and storage.