AlSb/ZrS2 heterojunction: A direct Z-scheme photocatalyst with high solar to hydrogen conversion efficiency and catalytic activity across entire PH range

Abstract

Using the First principles method, the electrical, optical, and photocatalytic characteristics of AlSb/ZrS2 van der Waals heterojunctions (vdwH) with direct Z-scheme photogenerated electron transfer mechanism were calculated in this study. The inherent type-II band structure, the built-in electric field that facilitates photogenerated carrier separation, and the high mobility of electrons and holes along the x and y axes all contribute to the strong photocatalytic activity. Furthermore, the AlSb/ZrS2 van der Waals heterojunction has better light absorption performance than monolayers, with a light absorption coefficient of 4.7 × 105 cm−1 at 500 nm and a solar to hydrogen efficiency of 25.81%. Meanwhile, the breakdown reaction of heterojunctions for water can be spontaneously reacted under the light, according to the free energy calculations of the Hydrogen Evolution Reaction (HER) and Oxygen Evolution Reaction (OER) processes. Unexpectedly, adding biaxial strain to the heterojunction allows for effective band gap and light absorption coefficient adjustments. and the photolysis reaction of water can be realized in the whole PH range within a suitable strain range. The AlSb/ZrS2 van der Waals heterojunction is expected to be a promising candidate for Z-scheme heterojunction photocatalysts for the whole hydrolysis in the future.