A novel covalent triazine-based frameworks as photocatalysts for the degradation of dyes under visible light irradiation

A range of phenyl- or thiophene-linked covalent triazine-based frameworks were synthesized by Suzuki polycondensation of 1,4-phenylenebisboronic acid and brominated phenyl or thiophene substituted triazine monomers. The materials obtained exhibited good thermal stability, tunable fluorescence properties, and strong visible-light harvesting ability. The photocatalytic performance of dye degradation was systematically studied, and the results showed that without adjusting pH or adding oxidants, the materials exhibited unprecedented degradation ability to both acidic and basic dyes. Under outdoor conditions, the resulting materials can degrade dyes at a concentration of up to 500 ppm to completely colorless within six weeks. The quenching tests indicate that the reactive species in the process of dye degradation is O-2(-), and the degradation rate constants for methyl orange (MO), Congo red (CR), methylene blue (MB) and rhodamine B (RB) are much higher than that for other reported catalytic systems. In addition, as photocatalysts, the materials also showed good reusability and stability.