摘要
Dye sensitization, as an effective method to modify the optical properties of TiO 2 , has wide applications in photocatalysis and solar cells. Carboxy-functionalized dyes can form stable ester bonds on the TiO 2 surface, which facilitates the transfer of photogenerated electrons. Therefore, the addition of esterification reaction catalysts inevitably influences the sensitization process. This study systematically investigates the catalytic effects of acid catalysts, basic reagents and organocatalysts on carboxy-functionalized dye-sensitized TiO 2 composites, with a focus on their photocatalytic performance and underlying mechanisms. The infrared spectroscopy characterization results confirmed the successful anchoring of the dye on the TiO 2 surface and the formation of ester bonds. Unlike the inhibition of esterification reactions by base reagents, both acid catalysts and organocatalysts led to higher esterification degrees in the dye-TiO 2 system. UV–Vis spectra showed that the dye-TiO 2 systems catalyzed by different catalysts exhibited distinct visible-light absorption compared with pure TiO 2 . Notably, dye-TiO 2 (HNO 3 ) and dye-TiO 2 (EDC-DMAP) demonstrated the optimal visible-light absorption in the acid-catalyzed and organic-catalyzed systems, respectively. EIS confirmed that both acid and organic catalysis resulted in lower interfacial impedance in the dye-TiO 2 system, implying superior charge transfer efficiency and photocatalytic activity. Photocatalytic experiments were also conducted to verify the aforementioned characteristics. Compared with dye-TiO 2 , dye-TiO 2 system catalyzed by acid catalysts exhibited the best photocatalytic performance. The photocatalytic efficiency of dye-TiO 2 system catalyzed by organocatalysts had also been improved. In contrast, the dye-TiO 2 system involving basic reagents showed lower photocatalytic performance than the uncatalyzed dye-TiO 2 system.
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