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Abstract
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Over the past years, an interest has arisen in resolving the problems of the increased carbon
monoxide and carbon dioxide emissions, leading to the serious air pollution and many detri-
mental e®ects. A convenient solution would be a process that could utilize metal oxide nano-
particles such as TiO2 to control the concentration of atmospheric pollutants. The
chemisorption of CO and CO2 molecules over the semiconductor titanium dioxide (TiO2 Þ is such
a process. In this way, density functional theory (DFT) calculations were performed to inves-
tigate CO and CO2 adsorptions on undoped and N-doped TiO2 anatase nanoparticles. The
supercell approach is conducted to construct the considered nanoparticles and the adsorption of
COx molecule was simulated by use of these chosen nanoparticles. By including van der Waals
(vdW) interactions between COx molecule and TiO2 nanoparticle, we found that both CO and
CO2 molecules can bind strongly to the N-doped nanoparticles. The adsorption on the ̄ve-fold
coordinated titanium site of TiO2 nanoparticles including the bond lengths, bond angles, ad-
sorption energies, density of states (DOSs), Mulliken population analysis and molecular orbitals
has been broadly studied in this work. Based on the obtained results, it can be concluded that
the adsorption on the N-doped nanoparticle is more energetically favorable than the adsorption
on the pristine one, representing the higher tendency of N-doped nanoparticles for COx de-
tention, compared to the undoped ones. Therefore, the results indicate that the N-doped TiO2
would be an ideal COx gas sensor in the environment.
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