▎ 摘　　要

The current study investigates the photocatalytic properties of Ir(III) complex-graphene quantum dot (GQD) nanocomposites for potential applications in photocatalysis using density functional theory calculations. The 2aryl substituent with strong electron-accepting strength leads to better charge transfer ability of the nanocomposite, while the one with strong electron-donating strength redshifts absorption peaks. The energy alignment between the Ir(III) complex and the GQD creates favorable conditions for charge injection to TiO2. Moreover, the electron-donating substituent increases the delocalization of it-electrons in the nanocomposite, enhancing the number of charge carriers injected to TiO2. Furthermore, the electron-donating group increases the charge carrier density of excited states and thus the light collection efficiency (LHE) of the nanocomposite. In contrast, the electron-withdrawing group reduces the LHE and thus the photoelectric conversion of the nanocomposite. The current study depicts the detailed role of electronegativity of the substituted functional group on the energy conversion process of Ir(III) complex-GQD nanocomposites.