Semiconducting Polyaromatic Covalent Organic Frameworks Constructed through Self-Aldol Condensation
Xiaoyi Xu, Yaoqian Feng, Hongzheng Chen, Ning Huang
Abstract
The construction of semiconducting covalent organic frameworks (COFs) via single-component self-polymerization is of broad interest in reticular chemistry. Herein, two semiconducting polyaromatic COFs with all-fused-ring conjugation structures were synthesized through the self-aldol condensation of indanone-based building blocks. The resulting COFs exhibit n -type semiconducting properties and exceptional stability under harsh acidic and alkaline conditions. The electrical conductivity and charge carrier mobility of the polyaromatic COFs reached up to 5.5 × 10 –3 S cm –1 and 0.62 cm 2 V –1 s –1, which ranked as the highest values among n -type semiconducting COFs. The high crystallinity, intrinsic porosity, excellent conductivity, and abundant five-membered rings as active sites render these COFs as effective metal-free electrocatalysts toward oxygen reduction reaction (ORR). Notably, one of these COFs shows a half-wave potential of up to 0.77 V under alkaline conditions, which constitutes one of the highest values among the reported metal-free ORR electrocatalysts. In addition, owing to the strong robustness of the polyaromatic COFs, they also exhibit long-term catalytic durability. This study not only expands the diversity of semiconducting COFs but also establishes new paradigms for the development of high-performance metal-free electrocatalysts toward the ORR process.