Adsorption of NO2 on WSe2: DFT and photoelectron spectroscopy studies

TL;DR

This study investigates how NO2 molecules interact with WSe2 surfaces, revealing moderate electronic structure changes through combined experimental photoelectron spectroscopy and theoretical DFT modeling, highlighting weak adsorption and valence band polarization effects.

Contribution

It provides new insights into NO2 adsorption effects on WSe2, combining experimental and theoretical approaches to elucidate electronic structure modifications.

Findings

Moderate upward shift of WSe2 bands upon NO2 adsorption

Weak adsorption energy of NO2 on WSe2 surface

Valence band polarization explains energy shifts

Abstract

The electronic structure modifications of WSe2 upon NO2-adsorption at room and low temperatures were studied by means of photoelectron spectroscopy. We found only moderate changes in the electronic structure, which are manifested as an upward shift of the WSe2-related bands to the smaller binding energies. The observed effects are modelled within the density functional theory approach, where a weak adsorption energy of gas molecules on the surface of WSe2 was deduced. The obtained experimental data are explained as a valence bands polarisation effect, which causes their energy shift depending on the adsorption geometry and the formed dipole moment.