Metal‐free Covalent organic frameworks for Oxygen Reduction Reaction

Oxygen reduction reaction (ORR) is the key reaction in metal air and fuel cells. Among the catalysts towards ORR, carbon-based metal-free catalysts are getting more attention because of their maximum atom utilization, effective active sites and satisfactory catalytic activity and stability. However, the pyrolysis synthesis of these carbons resulted in disordered porosities and uncontrolled catalytic sites, which hindered us to achieve the catalysts’ properties previously, and build the structure–property relationship at molecular level. Covalent organic frameworks (COFs) constructed with designable building blocks have been employed as metal free electrocatalysts towards oxygen reduction reaction (ORR) due to their controlled skeletons, tailored pores size and environments, and well-defined location and kinds of catalytic sites. In this concept article, the development of metal-free COFs for ORR is summarized, and different strategies including skeletons regulation, linkages engineering and edge-sites modulation to improve the catalytic selectivity and activity are discussed. Furthermore, this Concept provides prospective for design and construction high electrocatalysts based on the catalytic COFs.