DFT study on type-II photocatalyst for overall water splitting: g-GaN/C2N van der Waals heterostructure

Constructing van der Waals heterostructure has triggered enormous interest in the field of photocatalytic water splitting. Herein, we have investigated the structural, electronic and optical properties of g-GaN/C2N heterostructure by first-principles methods, and further discussed the implications from the viewpoint of photocatalytic applications. Our results show that g-GaN/C2N heterostructure is a type-II heterostructure, possessing staggered energy band arrangements, which benefits to the effective spatial-separation of photogenerated carriers. The bandgap is predicted to be 1.92 eV, governing a wide optical absorption spectrum from visible-light to ultraviolet-light with the magnitude of 105 cm-1. Moreover, its band edges span water redox potentials, satisfying the requirement of overall photocatalytic water splitting. In addition, the electronic properties of g-GaN/C2N heterostructure could be modulated by applying biaxal strain, resulting in an increasement of optical absorptions in the visible-light range. Finally, excellent stability of adsorbing watermolecule on the g-GaN/C2N heterostructure is shown. These theoretical predictions sug-gest that the g-GaN/C2N heterostructure is promising for photocatalytic water splitting. (c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

This study investigates the structural, electronic, and optical properties of g-GaN/C2N heterostructure and discusses its implications in photocatalytic water splitting. The results show that g-GaN/C2N heterostructure is a type-II heterostructure with staggered energy band arrangements, facilitating effective spatial separation of photogenerated carriers. The predicted bandgap is 1.92 eV, enabling wide optical absorption from visible-light to ultraviolet-light. The band edges of the heterostructure correspond to water redox potentials, meeting the requirements for overall photocatalytic water splitting. The electronic properties can be modulated by applying biaxial strain, leading to increased optical absorption in the visible-light range. The stability of water molecule adsorption on the heterostructure is also demonstrated. These theoretical predictions suggest the promising potential of g-GaN/C2N heterostructure in photocatalytic water splitting.