PtSe2/SiH van der Waals type-II heterostructure: a high efficiency photocatalyst for water splitting

Abstract

The construction of type-II van der Waals heterostructure is an effective method to design efficient photocatalysts. In this study, we constructed the PtSe₂/SiH van der Waals heterojunction, investigated its structural, electronic and optical properties, and discussed its application in photocatalysis. The PtSe₂/SiH heterostructure is an indirect bandgap heterojunction with a 1.553 eV bandgap. The phonon dispersion curves and electron localization functions are calculated to investigate the stability of the heterojunction and the bonding mechanism between layers. According to projected density of state, it is known that PtSe₂/SiH is a type-II band alignment. By calculating the work functions, the charge density difference and the plane-averaged electrostatic potential drop across the interface, we explored and discussed the interface charge transfer. In order to investigate the photocatalytic application of the PtSe₂/SiH heterostructure, the band edge position and absorption coefficient were calculated. The band edge position of the heterojunction crosses the redox potential of water, indicating that it has the ability for photocatalytic water splitting. Moreover, the excellent absorption coefficient of the PtSe₂/SiH heterojunction is higher than that of almost all previous studies. The absorption coefficient spans the whole region of visible light and has a peak value of 3.34 × 10⁵ cm⁻¹. Meanwhile, there was a peak of 4 × 10⁵ cm⁻¹ in the near ultraviolet region. Our results demonstrate that PtSe₂/SiH has excellent properties and is a promising photocatalytic candidate.