Spontaneous photo-generated carrier separation of SnO/BiOX (X=Cl, Br, I) bilayer under visible light irradiation for water splitting

TL;DR

This study designs SnO/BiOX bilayers with tunable bandgaps and effective charge separation, enhancing solar energy utilization and photocatalytic water splitting under visible light.

Contribution

Introduces novel SnO/BiOX bilayers with adjustable bandgaps and improved charge separation for efficient photocatalytic water splitting.

Findings

Bandgap tunable from 1.09 to 1.84 eV.

Enhanced charge separation reduces recombination.

Potential for overall water splitting under visible light.

Abstract

Alloying in 2D materials plays a more and more important role due to wide range bandgap tunability and integrating the advantages of HER and OER. Here, the novel bilayers of SnO/BiOX (X= Cl, Br and I) bilayer are constructed to integrate the advantages of narrow bandgap and separating photo-generated carriers. The bandgap of the bilayers can be tuned from 1.09 to 1.84 eV, remarkably improving the utilization of solar energy. The large difference in effective masses and built-in electric field effectively hamper the fast recombination of photo-generated carries, which highly enhances the photocatalytic efficiency. Besides that, the type-II band alignment guarantee the two half reactions could occur at different surfaces. Moreover, the optical absorption (the strong transition between band edges and high joint density of states) and band-edge level further confirm the SnO/BiOX (X= Cl and Br) bilayer is a promising candidate for overall water-splitting.