High hydrogen production in two-dimensional GaTe/ZnI2 type-II heterostructure for water splitting

In this work, first-principles calculation was used to systematically examine the structural, electronic, and optical properties of the GaTe/ZnI2 heterostructure under the biaxial strain effect. The frequency-dependent phonon dispersion relations and molecular dynamics simulations demonstrated the kinetic and thermodynamic stability of this heterostructure. The results showed that the GaTe/ZnI2 heterostructure possesses an indirect energy band of about 1.768 eV/1.065 eV (HSE06/PBE) and has a type-II band structure. In addition, results revealed that the GaTe/ZnI2 heterostructure has suitable band edge positions for redox reactions and could be a great photocatalyst for the splitting of water. Moreover, the optical properties were studied in the context of perpendicular field polarizations. Our calculations showed that this heterostructure has a high absorption coefficient reaching 4.5 x 104 cm-1 at 3.2 eV in visible light with the maximum value in the UV region. Overall, the electronic and optical properties of the heterostructure improved significantly. Our findings indicated that the GaTe/ZnI2 heterostructure can be used not only in photocatalysts but also in the photodetectors, gas sensors, and photovoltaic devices.