Photocatalytic water splitting of polarized GeS/Zr2CO2 heterostructure by biaxial strain engineering

Abstract

Type-II heterostructures have gained popularity in photocatalysis due to their ability to suppress carrier recombination. One distinctive approach towards achieving superior photocatalytic efficiency is by constructing heterostructures using 2D polarized materials. In this work, we constructed a GeS/Zr2CO2 heterostructure and investigated its built-in electric field and photocatalytic properties using first-principles calculations, with a focus on the effects of biaxial strain engineering. Our results indicated that under biaxial tension, the band alignment of GeS/Zr2CO2 heterostructure changed from a type-I to a type-II, while maintaining an indirect band gap. The GeS/Zr2CO2 heterostructure possessed a built-in electric field induced by dipoles and interfacial effects from the GeS monolayer and the interface between two monolayers, respectively, which increased with biaxial tension. Additionally, the GeS/Zr2CO2 heterostructure exhibited superior light absorption compared to individual monolayers, which was further enhanced by biaxial tension. The stretched 3% (4%) GeS/Zr2CO2 heterostructure has a remarkable STH efficiency of 21.2% (20.6%). Moreover, their anisotropic me* and lower mh* can enhance the efficiency of photocatalytic reactions by suppressing carrier recombination. These results suggest that the GeS/Zr2CO2 heterostructure hold great potential as water-splitting photocatalysts, and biaxial strain is a promising approach for developing high-performance photocatalysts in the foreseeable future.