Oxygen vacancies confined in conjugated polyimide for promoted visible-light photocatalytic oxidative coupling of amines

Conjugated polyimide (R-PI) containing triazine ring was synthesized by a modified thermal solid-state polymerization of the salt monomer. The structure of the as-prepared R-PI was characterized by FTIR, XPS, EPR, EA and solid-state 13 C NMR, which is rich in oxygen vacancies (OVs). The R-PI exhibits excellent catalytic performance for selective benzylamine oxidation reactions under visible light. Both experimental and theoretical calculation results indicated that the introduction of OVs could increase the level of electron delocalization of R-PI. R-PI possess more excitable electrons and a narrower band gap, which expands the absorption of long-wavelength light. The surface OVs also serve as excellent sites for molecular O 2 adsorption and activation. Chemisorbed O 2 spatially builds up a channel for the delivery of photoexcited electrons to O 2 , which effectively enhanced separation efficiency of photogenerated charge carriers. These results indicate that OVs-rich conjugated polyimides can be efficient visible light-responsive photocatalysts for green synthesis.