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

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.