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

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2024-12, Vol.21 (5), p.e2409620-n/a
• Main Authors: Li, Aoshuang, Tan, Yan, Wang, Yijie, Shen, Shuwen, Jia, Runlong, Cheng, Yiwen, Cong, Chunxiao, Zhang, Yuzhong, Guan, Cao, Cheng, Chuanwei
• Format: Article
• Language: English
• Subjects: Charge efficiency; Chelating agents; Chelation; Cobalt oxides; Construction sites; Cycles; Density functional theory; Electrocatalysts; Electron spin; Electron transfer; Infiltration; macroporous structure; Metal air batteries; Metal oxides; Mutual coupling; oxygen evolution reaction; oxygen reduction reaction; Polystyrene resins; Self-assembly; Sol-gel processes; Sucrose; sucrose‐assisted sol‐gel method; Zinc-oxygen batteries
• ISSN: 1613-6810; 1613-6829; 1613-6829
• DOI: 10.1002/smll.202409620

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 RuCoOx‐IO exhibits outstanding bifunctional oxygen activity with an ultra‐narrow oxygen potential gap of 0.598 V, and the Zn‐air batteries based on RuCoOx‐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. A universal approach is proposed for synthesizing 3D ordered macroporous (3DOM) metal oxides, successfully preparing over 20 kinds of 3DOM metal oxides with large‐scale structural uniformity, which solves the bottleneck problem of structural defects in 3DOM materials and universal limitations of the sol‐gel method. The representative RuCoOx‐IO achieves excellent bifunctional oxygen electrocatalysis activity with an ultralow potential gap of 0.598 V.