Covalent organic frameworks as emerging photocatalysts and electrocatalysts for renewable energy conversion

Covalent organic frameworks (COFs) have emerged as efficient photo- and electrocatalysts owing to their ordered structures, high porosity, tunable electronic structures, and modular functionality. Recent developments have revealed the immense potential of COF-based catalysts in renewable energy generation processes, particularly in the oxygen evolution reaction (OER), oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), and carbon dioxide reduction reaction (CO₂RR). Several strategies, including heteroatom doping, metalation, engineering of donor-acceptor units, and hybridization with conductive materials, have demonstrated substantial enhancement in the catalytic efficiency of COFs. This review presents a comprehensive overview of the latest strategies employed to improve the catalytic performance of COFs. The fundamentals of electrocatalysis and photocatalysis involved in the energy generation and conversion processes are also discussed. Synthetic methods and structural features of COFs critically influence their catalytic efficiency. Therefore, various synthetic approaches and characterization techniques for COFs are also described. In addition, existing challenges in the practical use of COF-based catalysts and the future perspectives for the continued development of robust and efficient COF-derived photo- and electrocatalysts for sustainable and scalable energy technologies are discussed.