A new triazine-based conjugated polymer from simple monomers with stable photocatalytic hydrogen evolution under visible light

A new triazine-based conjugated polymer THT-TA was constructed with simple building blocks 2,4,6-trihydrazino-1,3,5-triazine (THT) and terephthalaldehyde (TA) via solvothermal reaction. The structural characterizations confirmed the successful synthesis of the polymer, and TEM images clearly revealed the sheet-like morphology. The 2D layered structure was further confirmed by XRD, and the semi-crystalline pattern was better fitted with a novel parallelogram framework rather than classic hexagonal framework. The optical band gap of THT-TA was 2.50 eV, and the frontier orbitals were delocalized across the framework from DFT calculation, validating that higher degree of conjugation was achieved from small monomers. The photocatalytic hydrogen evolution was successfully achieved with Pt as co-catalyst and sodium ascorbate as sacrificial agent under visible light (lambda > 420 nm), and the sample showed considerable stability in the long-term test for more than 200 h.