A General Sol-Gel Route to Fabricate Large-Area Highly-Ordered Metal Oxide Arrays Toward High-Performance Zinc-Air Batteries

A universal method is demonstrated for the fabrication of large-area highly ordered microporous arrayed metal oxides based on a high-quality self-assembly opal template combined with a sucrose-assisted sol-gel technique. Sucrose as a chelating agent optimizes precursor infiltration and regulates both oxide formation and the melting process of polystyrene templates, thus preventing crack formation during infiltration and calcination. As a result, over 20 metal element-based 3DOM oxides with arbitrary compositions are successfully prepared. Therein, a champion electrocatalyst RuCoO_x-IO exhibits outstanding bifunctional oxygen activity with an ultra-narrow oxygen potential gap of 0.598 V, and the Zn-air batteries based on RuCoO_x-IO air cathode operates for 1380 h under fast-charging cycling (50 mA cm⁻²), and reaches a high energy efficiency of 69.5% in discharge-charge cycling. In situ spectroscopy characterizations and density functional theory reveal that the rational construction of Ru─O─Co heterointerface with decoupled multi-active sites and mutual coupling of RuO₂ and Co₃O₄ facilitate interfacial electron transfer, leading to an optimized d-band centers of active Ru/Co and a weakened spin interaction between oxygen intermediates and Co sites, so as to enhance the adsorption ability of ^*OOH on interfacial Co sites for fast ORR kinetics while favoring the desorption of oxygen intermediates on interfacial Ru during OER.