Investigation on photocatalytic mechanism of graphitic SiC (g-SiC)/MoS2 van der Waals heterostructured photocatalysts for overall water splitting

Abstract

Two-dimensional MoS₂-based heterostructures have been given great attention due to their excellent properties. In this work, using first-principles calculations, the photocatalytic performances for overall water splitting and the photocatalytic mechanism of graphitic SiC (g-SiC)/MoS₂ van der Waals heterostructures (vdWHs) have been deeply studied compared with the previous report. We align common type-II band edges for the g-SiC/MoS₂ vdWH in different configurations, which demonstrates that the reduction and oxidation reactions are conducted on different parts in the g-SiC/MoS₂ vdWHs. Besides, the built-in electric field induced by the charge transfer at the interface region can be used to hinder photogenerated e⁻/h⁺ from recombining, which is advantageous to the availably enhanced carrier mobility and extended lifetimes. More meaningfully, the g-SiC/MoS₂ vdWHs all have considerable optical absorption as high as 10⁵ cm⁻¹ in the visible zone and enhanced absorption capacity in contrast to the separate g-SiC and MoS₂ monolayers. Furthermore, owing to the contribution of built-in electric field, the g-SiC/MoS₂ vdWH in diverse patterns can be used as an outstanding photocatalyst even under near-infrared light with high efficiency. Overall, these findings predict a promising application prospective for the g-SiC/MoS₂ vdWHs as extraordinary photocatalysts for overall water splitting reactions, suggesting the valuable significance in the fields of hydrogen production and energy conversion.