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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