Hexaazatriphenylene doped carbon nitrides-Biomimetic photocatalyst with superior oxidation power

- Carbon Nitrides modified with Hexaazatriplenylene (HAT) have been developed.
- Introduction of HAT units lowers valence band position of the material to 2.6 eV.
- Semiconductors optical bandgaps (BG) of modified materials narrows to 1.55 eV.
- HAT doping highly increases rate of photocatalytic oxygen evolution reaction.

Pyrazine rings are a fundamental part of folic acid and flavine - cofactors that participate in natural electron transfer processes. Electron deficient carbon nitrides, more specifically poly(heptazine imides) (PHI), emulating the structure of these pyrazine based cofactors were synthesized polymerizing 3-amino-1,2,4-triazole-5-thiol with hexaazatriphenylene-hexacarbonitrile or hexaazatriphenylene-hexaamide at 550 °C in the eutectic mixture of KCl/LiCl. The role of hexaazatriphenylene units is 1) to create electron deficient acceptor sites in the structure of semiconductor; 2) widen the spectral coverage up to near infrared region. The significantly increased oxidative power of such doped PHI was demonstrated by running oxygen evolution from water, 0.59 μmol h−1, under visible light irradiation in the absence of any metal co-catalyst.

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