Tailoring the optoelectronic properties and dielectric profiles of few-layer S-doped MoO3 and O-doped MoS2 nanosheets: a first-principles study

Masoud Shahrokhi (1, 2) , Tangui Le Bahers (2) , Pascal Raybaud (1, 2)

1 IFPEN - IFP Energies nouvelles
2 LC - Laboratoire de Chimie - UMR5182

To gain insights into few layer (FL) van der Waals MoO 3Àx S x /MoS 2Àx O x heterostructures for photocatalytic applications, we analyze how the concentration (x) and location of anionic isovalent atom (S or O) substitutions impact their opto-electronic properties and high frequency dielectric constant profiles. By using density functional theory (DFT) calculations within the HSE06 functional, we show that the electronic band gap of FL MoO 3Àx S x decreases with increasing x, while the dielectric constant profile and absorption coefficient in the UV-vis range increase. The stronger band gap reductions are obtained when S-atoms are located in the internal bulk region of FL MoO 3Àx S x and in interaction with O-atoms of the neighboring layer. Moreover, the conduction and valence band (CB/VB) levels are shifted to higher energy values in the case of the edge location (external surface) of these S-atoms. Thanks to the determination of the thermodynamic diagrams of 4L MoO 3Àx S x and 6L MoS 2Àx O x , we propose optimal heterojunctions made of 4L MoO 3Àx S x with either single-layer (SL) or FL MoS 2 with CB/VB levels compatible with a Z-scheme working principle and with potentials required for photocatalysis applications such as the photolysis of water into O 2 and H 2. This study combined with our previous theoretical investigations on bulk materials and SL provides a thorough analysis of SL-FL MoO 3Àx S x / MoS 2 heterojunctions where the concentration and location of S-atoms in MoO 3Àx S x are key to design efficient materials for water photolysis.

Domaines: Micro et nanotechnologies/Microélectronique

Masoud Shahrokhi, Tangui Le Bahers, Pascal Raybaud. Tailoring the optoelectronic properties and dielectric profiles of few-layer S-doped MoO3 and O-doped MoS2 nanosheets: a first-principles study. Physical Chemistry Chemical Physics, 2022, 24 (41), pp.25440 - 25451. ⟨10.1039/d2cp03410g⟩. ⟨hal-03868240⟩