Advances in covalent organic frameworks for photocatalytic CO <sub>2</sub> reduction: Strategies and future perspectives
Muhammad Kashif Aslam, Iftikhar Hussaın, Ali H. Al‐Marzouqi, Maowen Xu
Abstract
The rapid depletion of fossil fuels and increasing emissions of greenhouse gases, particularly CO<sub>2</sub>, have amplified global energy and environmental challenges. Converting CO<sub>2</sub> into valuable fuels through photocatalytic processes offers a sustainable solution to these issues, especially by utilizing solar energy to drive CO<sub>2</sub> reduction into energy-dense compounds. Covalent organic frameworks (COFs), a unique class of crystalline and porous organic polymers, have emerged as promising photocatalysts due to their structural stability, tunable porosity, and adaptable functionality. These properties enable COFs to support various catalytic sites, both metallic and non-metallic, facilitating selective and efficient CO<sub>2</sub> reduction. This review systematically examines the intrinsic properties of COFs, the synthetic methods used to optimize their structures, and the functional modifications that enhance their photocatalytic capabilities. We explore how COFs with metal and non-metal active sites, as well as hybrid COF catalysts, advance photocatalytic CO<sub>2</sub> reduction and analyze the driving forces behind CO<sub>2</sub> reduction reaction (CO<sub>2</sub>RR). Finally, we summarize recent breakthroughs and offer perspectives on future research directions in COF material synthesis, functional modifications, and mechanistic studies to further improve CO<sub>2</sub> reduction efficiency and sustainability.