A promising direct Z-scheme SnC/MoS2 heterojunction with superior optical absorption, high STH efficiency and strong catalytic activity for overall water-splitting

Abstract

In this paper, we choose the SnC and MoS₂ layers to construct heterojunction and investigate its geometrical stable, electrical property, charge transport, light absorption, solar-to-hydrogen energy conversion efficiency and photocatalytic performance using first-principles calculations. The results show that the SnC/MoS₂ heterojunction is a semiconductor exhibiting a staggered (type-II) arrangement with an indirectly bandgap of 1.125 eV and good thermodynamic and thermal stabilities, which suppresses the photogenerated electron-hole pair recombination and significantly boosting the photocatalysis performance. The SnC/MoS₂ heterojunction has a good band-edge positions to induce water decomposition, leading to the conduction-band reduction reaction on the SnC surface to generate H₂ as well as the valence-band oxidation reaction on the MoS₂ surface to produce O₂. Furthermore, the SnC/MoS₂ heterojunction has superior light absorbance compared with two single layers, showing the maximum absorbance peaks of 5.29 × 10⁵ cm⁻¹ in the visual light range, and higher solar-to-hydrogen energy conversion efficiency of 53.19 %. In addition, Gibbs free energy calculations show that the SnC/MoS₂ heterojunction has high catalytic activity for redox reactions. All these show that the SnC/MoS₂ heterojunction is a high efficiency direct Z-scheme heterojunction photocatalyst for over water-splitting.