Real roles of perylene diimides for improving photocatalytic activity

Abstract

Three novel visible-light-driven composite photocatalysts were synthesized by hydrothermal method. The effects of introducing PDIs with different structures into TiO2 were evaluated by assaying the photodegradation rate of methylene blue.

Photoactivation Properties of Self-n-Doped Perylene Diimides: Concentration-Dependent Radical Anion and Dianion Formation

“…Figure 1B shows the absorption spectra of A2I solutions kept in the dark. The S0→S1 perylene core absorption band at 526 nm (0-0) is accompanied by Franck-Condon vibronic transitions 0-1 (490 nm), 0-2 (459 nm), and 0-3 (430 nm) that are characteristic of neutral PDI photoexcitation in solution (N→ 1 [N]*). The peak ratio 0-0/0-1 is often used to measure the degree of aggregation, with higher values (~1.7) being indicative of monodispersity and lower values (~1) indicating H-type aggregation.…”

“…To understand this trend, we first discuss the photoinduced electron transfer mechanism in PDIs. [28][29][30] In Figure 3, ground state N is photoexcited to 1 [N]*, and R •then forms when 1 [N]* is reductively quenched by the anion. The difference between this and previous reports is that, in the case of self-n-doping, the process is not diffusion limited but instead mediated by chain rotation as the dopant folds back toward the imide acceptor moieties.…”

“…Perylene diimide (PDI) small organic molecules have become an increasingly relevant class of material in a broad range of applications beyond simple pigments, such as in biological systems, thermoelectrics, optoelectronics, sensing, photocatalysis, and synthetic photochemistry. [1][2][3][4][5][6][7] The successful utilization of PDIs in many of these applications requires an effective doping method to produce free carriers in the solid-state or radical anions in solution. For example, PDIs have garnered attention in synthetic photochemistry, such as aryl halide reduction and olefin iodoperfluoroalkylation, wherein the PDI is reduced by a sacrificial reductant under illumination to generate the radical anion R •-.…”

“…[R •-]*, and N is excited to1 [N]*. Electronic diagrams for each of these pathways are illustrated in Figure6C.…”

Hydrothermal synthesis of novel 1-aminoperylene diimide/TiO2/MoS2 composite with enhanced photocatalytic activity

“…PDIs have been introduced into TiO 2 , ZnO, and other photocatalysts to improve the photocatalytic performance 14 , 15 . However, such composite materials still have some defects such as quick recombination of photoexcited electron–hole pairs and photoetching, which lead to low efficiency of visible light driven photodegradation 16 . Therefore, it is necessary to further improve their photocatalytic activities and stabilities.…”