Two-Dimensional Covalent Organic Frameworks with Carbazole-Embedded Frameworks Facilitate Photocatalytic and Electrocatalytic Processes

Abstract

Catalytic technologies are pivotal in enhancing energy efficiency, promoting clean energy production, and reducing energy consumption in the chemical industry. The pursuit of novel catalysts for renewable energy is a long-term goal for researchers. In this work, we synthesized three two-dimensional covalent organic frameworks (COFs) featuring electron-rich carbazole-based architectures and evaluated their catalytic performance in photocatalytic organic reactions and electrocatalytic oxygen reduction reactions (ORRs). Pyrene-functionalized COF, termed as FCTD-TAPy, demonstrated excellent photocatalytic performance for amino oxidation coupling and showed a remarkable preference for substrates with electron-withdrawing groups (up to >99% Conv. and >99% Sel). Furthermore, FCTD-TAPy favored a four-electron transfer pathway during the ORR and exhibited favorable reaction kinetics (51.07 mV/dec) and a high turnover frequency (0.011 s−1). In contrast, the ORR of benzothiadiazole-based FCTD-TABT favored a two-electron transfer pathway, which exhibited a maximum double-layer capacitance of 14.26 mF cm−2, a Tafel slope of 53.01 mV/dec, and a hydrogen peroxide generation rate of 70.3 mmol g−1 h−1. This work underscores the potential of carbazole-based COFs as advanced catalytic materials and offers new insights into the design of metal-free COFs for enhanced catalytic performance.

Keywords

• carbazole
• covalent organic framework
• photocatalysis
• oxygen reduction reactions
• electrocatalysis
• thiazole