Enhanced Photocatalytic Reduction of <scp> CO <sub>2</sub> </scp> to Complete <scp>CO</scp> Mediated by Donor–Acceptor Covalent Organic Frameworks
Yi Li, Longyan Wang, Deqi Fan, Zhaolin Li, Chengxiao Zhao, Xiaofei Yang
Abstract
The photocatalytic behavior of covalent organic frameworks (COFs) for carbon dioxide (CO 2 ) reduction is dependent on the structure and physicochemical properties; CO 2 photoreduction performance is generally influenced by multiple effects rather than a single variable. Rational design and construction of donor (D)‐acceptor (A) type COFs have emerged as an ideal strategy for improving photocatalytic CO 2 reduction performance. However, it is still challenging to unveil the influence of building blocks on catalytic activity and selectivity of CO 2 conversion in D–A COFs. Herein, we report a modified solvothermal method to construct β‐ketoenamine‐linked COFs based on a one‐step Schiff base condensation reaction. By employing 1,3,5‐triformylphloroglucinol (TP), which enables both chemical stability and crystallinity of COFs as the electron acceptor, and 1,3,5‐tris(4‐aminophenyl)triazine (TAPT), 2,4,6‐tris(4‐aminophenyl)pyridine (TAPP), and 1,3,5‐tris(4‐aminophenyl)benzene (TAPB) as the electron donors, respectively, we synthesized three distinct COF materials with different intensities of the D–A interaction, based on the molecule design, to regulate the microenvironment for CO 2 photoreduction in pure water. The incorporation of D–A moieties into COFs remarkably accelerates charge separation and transport via enhanced D–A interaction or reinforced charge density difference. TP‐TAPB COF, featuring the strongest D–A interaction, exhibited the highest CO production rate of 464.6 μmol g −1 with nearly 100% selectivity, 7.2 times higher activity than TP‐TAPT.