Issue 8, 2018

The roles of buckled geometry and water environment in the excitonic properties of graphitic C3N4

Abstract

The exciton plays a crucial role in two-dimensional materials involved in photocatalytic water splitting, where its properties are determined not only by the material itself, but also by the surrounding water environment. By the framework of many-body perturbation theory, we investigated the excitonic effects in pure and water-adsorbed g-C3N4. It is shown that the excitonic properties are very sensitive to the geometry of g-C3N4 and the adsorption of water molecules. Firstly, the optical band gap, i.e. the first bright excitonic energy of pure g-C3N4 decreases remarkably from a high symmetry planar structure (3.8 eV) to a P1 buckled configuration (2.7 eV). Secondly, the hydrogen bonds between water and g-C3N4 induce the generation of interface excitons. With a reduced binding energy (at least 0.2 eV), interface excitons can contribute to a more efficient separation of electrons and holes. Our work provides an insight into the excitation mechanism of 2D photocatalysts in a real environment.

Graphical abstract: The roles of buckled geometry and water environment in the excitonic properties of graphitic C3N4

Supplementary files

Article information

Article type
Paper
Submitted
16 Nov 2017
Accepted
19 Jan 2018
First published
22 Jan 2018

Nanoscale, 2018,10, 3738-3743

The roles of buckled geometry and water environment in the excitonic properties of graphitic C3N4

J. Sun, X. Li and J. Yang, Nanoscale, 2018, 10, 3738 DOI: 10.1039/C7NR08541A

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