MoS₂/ZnO van der Waals heterostructure as a high-efficiency water splitting photocatalyst: a first-principles study

Abstract

Previous investigations [H. L. Zhuang and R. G. Hennig, J. Phys. Chem. C, 2013, 117, 20440-20445; J. Kang, S. Tongay, J. Zhou, J. Li and J. Wu, Appl. Phys. Lett., 2013, 102, 012111] demonstrated that molybdenum disulfide (MoS2) is a potential photocatalyst for water splitting. However, the photogenerated electron-hole pairs in MoS2 remain in the same spatial regions, resulting in a high rate of recombination. Using first-principles calculations, we designed a MoS2-based heterostructure by stacking MoS2 on two-dimensional zinc oxide (ZnO) and investigated its structural, electronic, and optical properties. The interaction at the MoS2/ZnO interface was found to be dominated by van der Waals (vdW) forces. The energy levels of both water oxidation and reduction lie within the bandgap of the MoS2/ZnO vdW heterostructure, which guarantee their occurrence for water splitting. Moreover, a type-II band alignment and a large built-in electric field are formed at the MoS2/ZnO interface, which ensure the enhanced separation of the photogenerated electron-hole pairs. In addition, strong optical absorption in the visible region was also found in the MoS2/ZnO vdW heterostructure, indicating that it has potential for application in photovoltaic and photocatalytic devices.

HfS2/MoTe2 vdW heterostructure: bandstructure and strain engineering based on first-principles calculation

“…They all are the macroscopic phenomena of electron transitions between energy bands in solid under the perturbation of photoelectric magnetic eld. 57 Obviously, at both the X and Y directions the dielectric peaks are in the visible range, while at the Z direction the dielectric peak is in the ultraviolet region. The calculation of the imaginary part of the dielectric constant 3 2 of the HfS 2 /MoTe 2 multilayer heterostructure as a function of energy is illustrated in Fig.…”

“…Since materials with type-II heterostructure alignment are regarded to make hole-electron separation more efficient, and can be used for optical absorption in a wider range of solar spectra, 53,57 in order to reveal the unique characteristics of HfS 2 / MoTe 2 , a detailed discussion of its imaginary part of the dielectric constant 3 2 for light absorption is given. In the linear response range, the complex dielectric response function to describe the optical properties of a material is 3 ¼ 3 1 + i3 2 , where 3 1 denotes the real part calculated by the well-known Kramers-Kronig relation and 3 2 is the imaginary part obtained from the matrix elements of the wave function for occupied and nonoccupied states.…”

Strain-enhanced properties of van der Waals heterostructure based on blue phosphorus and g-GaN as a visible-light-driven photocatalyst for water splitting

“…Many strategies have been put in place to advance "green" technologies, and the development of photocatalysts for water splitting is considered to be a promising measure because these catalysts can break down water into hydrogen (H 2 ) and oxygen (O 2 ) under the illumination of visible light to produce sustainable and renewable energy. 1 As photoelectrochemical (PEC) water splitting by semiconductors attracts more and more attention, [2][3][4][5] it has been reported that a crucial requirement for water splitting is a suitable band edge of the semiconductor, 1,6 where the conductionband minimum (CBM) of the material should be greater than the reduction potential (À4.44 eV) for H + /H 2 , and the valenceband maximum (VBM) of the material should be less than the oxidation potential (À5.67 eV) for O 2 /H 2 O, 7 which means the bandgap of any qualied photocatalyst should be more than 1.23 eV. 8 Fig.…”

Developing the Ternary ZnO Doped MoS2 Nanostructures Grafted on CNT and Reduced Graphene Oxide (RGO) for Photocatalytic Degradation of Aniline

“…Furthermore, rapid recombination of photo-induced pairs of electron-hole in the photocatalytic reaction would cause a reduction in its efficiency. The previous studies showed that coupling this semiconductor with a narrow bandgap semiconductor has resulted in an improvement in its light absorption range and yielded better catalytic results [33][34][35][36][37][38][39][40] . For instance, Tan et al reported that incorporation of ZnO into MoS 2 could result in easy transfer of electrons to the ZnO surface.…”