SiC/PtSe2 van der Waals heterostructure: A high-efficiency direct Z-scheme photocatalyst for overall water splitting predicted from first-principles study

Abstract

The discovery of effective photocatalytic substances is crucial in reducing energy shortages and ecological contamination. This research involves creating SiC/PtSe₂ van der Waals heterostructure with both SiC and PtSe₂ monolayers, employing first-principles calculations for comprehensive theoretical analysis of their structural stability, electronic characteristics, optical features, Bader charge, and solar-to-hydrogen (STH) efficiency. Findings indicate that the SiC/PtSe₂ heterostructure is a semiconductor with an indirect bandgap of 1.52 eV and a direct Z-scheme charge transfer path, facilitating more efficient segregation of photogenerated electron-hole pairs. The Bader charge indicates that the SiC layer accumulates positive charges and the PtSe₂ layer accumulates negative charges, constituting a built-in electric field pointing from the SiC side to the PtSe₂ side at the interface region, which can impede the complexation of the photogenerated electron-hole pairs. Furthermore, the SiC/PtSe₂ heterostructure exhibits excellent optical absorption properties across both the ultraviolet and visible spectra, coupled with an exceptionally high STH efficiency of 34.7 %, significantly enhancing solar energy utilization. Ultimately, the Gibbs free energy calculations reveal the significant catalytic efficiency of the SiC/PtSe₂ heterostructure for redox reactions. Based on these results, the SiC/PtSe₂ heterostructure is a direct Z-scheme photocatalyst for overall water splitting.