Covalent organic framework with sulfonic acid functional groups for visible light-driven CO(2) reduction

In this study, a covalent organic framework (TpPa–SO(3)H) photocatalyst with sulfonic acid function groups was synthesized using a solvothermal method. The morphologies and structural properties of the as-prepared composites were characterized by X-ray diffraction, infrared spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, N(2) adsorption–desorption measurements, and field emission scanning electron microscopy. An electrochemical workstation was used to test the photoelectric performance of the materials. The results show that TpPa–SO(3)H has –SO(3)H functional groups and high photocatalytic performance for CO(2) reduction. After 4 h of visible-light irradiation, the amount of CO produced is 416.61 μmol g(−1). In addition, the TpPa–SO(3)H photocatalyst exhibited chemical stability and reusability. After two testing cycles under visible light irradiation, the amount of CO produced decreased slightly to 415.23 and 409.15 μmol g(−1). The XRD spectra of TpPa–SO(3)H were consistent before and after the cycles. Therefore, TpPa–SO(3)H exhibited good photocatalytic activity. This is because the introduction of –SO(3)H narrows the bandgap of TpPa–SO(3)H, which enhances the visible light response range and greatly promotes the separation of photogenerated electrons.