共价有机框架材料(COFs)在氧电极电催化中的研究进展

Recent advances in covalent organic frameworks(COFs)for electrocatalysis of oxygen electrodes

在碳达峰、碳中和的目标之下,燃料电池、金属-空气电池、电解水等清洁能源技术提高了能源利用率,在未来将成为新的能源消费方式。氧还原反应(ORR)、氧析出反应(OER)因其缓慢的动力学过程而导致此类清洁能源技术的发展受到阻碍。贵金属催化剂虽被认为是最高效的催化剂,但其成本高、稳定性低,寻找非贵金属催化剂已成为相关研究的趋势。共价有机框架材料(COFs)作为一类新兴的材料,由有机单体通过特殊的共价键连接而成,因其具有可调控的结构、低密度、高稳定性、较大比表面积等独特的优点,通过合理的设计策略,将其应用于电催化剂的研究在近年来逐步兴起。本文回顾了近期适用于ORR、OER及ORR/OER双功能电催化的二维COFs(2D COFs)材料,主要介绍了以纯COFs作为电催化剂、COFs与其他材料形成复合结构、COFs热解碳化等策略制备高效电催化剂,并从分子设计及电子调控等层面上梳理了上述策略对电催化活性中心的形成或电催化活性提升的原因,对当前存在的问题提出总结,以期在今后的研究中起到一定借鉴意义。

Clean energy technologies such as fuel cells,water electrolysis,and metal-air batteries have improved energy efficiency and could become new energy consumption methods in the future to peak carbon dioxide emissions and achieve carbon neutrality.The sluggish kinetics of oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)hinder the development of these clean energy technologies.Although noble metal catalysts are considered superior,they have apparent disadvantages,such as poor durability,low selectivity,and high cost.The determination of noble metal-free catalysts has become a trend in related researches.As an emerging class of polymer materials linked by special covalent bonds,covalent organic frameworks(COFs)demonstrate advantages of tunable structure,low density,high stability,and large specific surface area.COFs are widely considered as promising electrocatalysts that can be gradually applied utilizing reasonable design strategies.Herein,this review aims to research 2D COFs suitable for ORR,OER,and bifunctional electrocatalysis in recent years and primarily introduces the strategies of pristine COF as an electrocatalyst,composite structure formation,and pyrolysis.The key factors for forming electrocatalytic active centers or improving electrocatalytic activity have been summarized from the molecular design and electronic tuning aspects,which are expected to serve as a reference in future works.