Thiazolo[5,4-d]thiazole-Based CMPs as Bifunctional Photocatalysts for H₂O₂ Production and Organic Pollutant Degradation

Two donor-acceptor (D-A)-type conjugated microporous polymers (CMPs), TT-PA and TT-BPA, are successfully synthesized based on thiazolo[5,4- d ]thiazole (TzTz) as the acceptor unit. The rigid plane of TzTz enables a close and effective π-π stacking between polymer layers, which is beneficial for the transport of charges between layers and the improvement of photocatalytic performance. The high-density S and N atoms in the TzTz units can act as Lewis base sites to adsorb O₂ molecules. Subsequently, TzTz transfers the photogenerated electrons to the adsorbed O₂, generating ·O₂⁻, which is conducive to the 2e ^- oxygen reduction reaction (ORR) pathway for the photocatalytic production of H₂O₂ and the degradation of the pollutant Rhodamine B (RhB). The PL, EIS and photocurrent data indicate that TT-PA has a lower charge recombination rate and higher charge separation efficiency, stemming from the appropriate size and electron-attracting ability of triphenylamine. Therefore, the combination of TzTz and triphenylamine in TT-PA is the "golden combination" for achieving the best D-A effect, pore structure and photocatalytic performance due to the best D/A ratio. This study gives insights into the design of CMP photocatalyst.