Enhancing charge transfer efficiency through carboxyl-modification to improve the photocatalytic activity of covalent organic frameworks for hydrogen evolution from water splitting

), positioning it among the most efficient metal-free COF photocatalysts reported to date. Density functional theory calculations and in situ X-ray photoelectron spectroscopy analyses indicate that carboxyl modification facilitates charge transfer from the porphine core to the active site of the imine bond (-CN-) under the ultraviolet-visible light irradiation, thereby contributing to the remarkable photocatalytic activity of Por-COOH-COF. This study elucidates how carboxyl groups positively influence photogenerated carrier separation within COFs and provides valuable insights into the development of high-performance metal-free COFs photocatalysts.