Abstract: Carbon nitride (CN) is constrained in its photocatalytic efficiency by the rapid recombination of photogenerated carriers, whereas the construction of localized charge polarization represents an effective strategy to overcome this bottleneck. In this study, supramolecular self-assembly was employed to modify the edges of CN with the strong electron-withdrawing 2-mercaptobenzothiazole (denoted as TF), resulting in CN-TF with localized charge polarization for the photocatalytic conversion of CO₂ to CH₄. The TF group disrupted the structural symmetry of CN and induced localized charge polarization through its strong electron-withdrawing properties. This polarization effect drove the directional migration of electrons from the CN matrix to the TF-modified region, where they selectively accumulated, thereby forming a localized high electron density region. Additionally, the S sites introduced by TF modification served as an active center to adsorb and activate CO₂, reducing the reaction activation energy. As expected, CN-TF₅₀ exhibited excellent performance with its activity for the photocatalytic reduction of CO₂ to CH₄ reached 10.11 µmol/(g h), which was 3.24 times higher than that of CN (3.12 µmol/(g h)). In short, this work illustrated the importance of constructing local polarization for promoting localized spatial charge separation, forming local high electron density in CN, and enhancing the performance of photocatalytic CO₂ to CH₄.

Key words: Carbon nitride, Photocatalysis, CO₂ reduction reaction, Charge transfer, Localized charge polarization