Issue 21, 2018

Mechanism of photocatalytic water splitting with triazine-based carbon nitrides: insights from ab initio calculations for the triazine–water complex

Abstract

Polymeric carbon-nitride materials consisting of triazine or heptazine units have recently attracted vast interest as photocatalysts for water splitting with visible light. Adopting the hydrogen-bonded triazine–water complex as a model system, we explored the photochemical reaction mechanisms involved in the water splitting reaction in this system, using wavefunction-based ab initio electronic-structure methods. It is shown that photoexcited triazine can abstract a hydrogen atom from the water molecule by the sequential transfer of an electron and a proton from water to triazine, resulting in the triazinyl-hydroxyl biradical in the electronic ground state. It is furthermore shown that the excess hydrogen atom of the triazinyl radical can be photodetached by a second photon, which regenerates the triazine molecule. The hydrogen-bonded water molecule is thus decomposed into hydrogen and hydroxyl radicals in a biphotonic photochemical reaction. These results shed light on the molecular mechanisms of the water-oxidation reaction catalyzed by triazine-based organic polymers.

Graphical abstract: Mechanism of photocatalytic water splitting with triazine-based carbon nitrides: insights from ab initio calculations for the triazine–water complex

Supplementary files

Article information

Article type
Paper
Submitted
28 Mar 2018
Accepted
08 May 2018
First published
11 May 2018

Phys. Chem. Chem. Phys., 2018,20, 14420-14430

Mechanism of photocatalytic water splitting with triazine-based carbon nitrides: insights from ab initio calculations for the triazine–water complex

J. Ehrmaier, M. J. Janicki, A. L. Sobolewski and W. Domcke, Phys. Chem. Chem. Phys., 2018, 20, 14420 DOI: 10.1039/C8CP01998C

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