Graphitic Carbon Nitride Modified with 2-Aminothiophene-3-Carbonitrile to Boost Molecular Dipole and n → π* Electronic Transition for Photoreduction of Carbon Dioxide

Charge-transfer dynamics and light utilization efficiency are two critical factors that significantly impact the catalytic performance of a photocatalyst. Therefore, developing a reasonable method to enhance these aspects is a valuable strategy for creating efficient photocatalysts. In this study, we fabricated a donor–acceptor (D–A) structure by modifying graphitic phase carbon nitride (g-CN) nanosheets with 2-aminothiophene-3-carbonitrile (ACT). The introduction of ACT altered the dipole moment of g-CN and significantly extended the conjugated system of g-CN, thereby enhancing the n → π* electronic transition. These improvements in molecular dipole and conjugated system effectively enhanced the charge-transfer dynamics and light utilization efficiency. In addition, the introduction of ACT greatly improved the CO2 adsorption capacity of g-CN nanosheets. Experimental results showed that g-CN-ACT0.05 exhibited the best photocatalytic CO2 reduction performance, with a CO evolution rate of 8.27 μmol g–1 h–1, which was eight times higher than that of unmodified g-CN. This research serves as a reference for developing catalysts with high photocatalytic activity for CO2 reduction.