Hydrogen production from water using MoX2/ZnO (X:S,Se) heterostructures as photocatalysts

Abstract

The role of two-dimensional heterostructures (HSs) in clean hydrogen production through photocatalytic water splitting has been paid enormous attention. Herein, we report a HS of transition metal dichalcogenide monolayer MoX2 where X–S,Se and graphene-like zinc oxide (g-ZnO). The structural,electronic, and optical properties have been investigated using density functional theory. MoS2/ZnO shows type-II band alignment with indirect bandgap of 1.61eV, a significant in-built potential of 7.42eV, and a valence band offset of 1.23eV across the interface, while MoSe2/ZnO HS shows type-I band alignment with direct bandgap of 1.80eV, in-built potential of 3.64eV, and a valence band offset of 0.34eV. Bandgap value and band-edge positions proved these HSs to be promising candidates for water splitting and evolution of hydrogen using solar energy. The results suggest the possibility of using 2D MoX2/ZnO HS as potential photocatalysts for straddling the redox potentials of water over a wide range, from ultraviolet to infrared spectra. The photogenerated charge carriers in the MoS2/ZnO HS are localized in different layers and can efficiently generate hydrogen energy by photocatalytic water splitting. However, the band-edge positions in MoSe2/ZnO are more suitable for pH = 8, making it promising photocatalyst for large-scale hydrogen production from solar energy.