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Discipline(s) enseignée(s)

Thomas A. Niehaus was appointed Professor in 2015 at the ILM in the team : Modélisation de la Matière Condensée et des Interfaces  and benefited from a Chair of the Labex iMUST.

Thèmes de recherche

Research interests : Light-matter interaction in nanostructures
Optoelectronic and energy conversion materials · Time-dependent Density Functional Theory · Computational nanoelectronics · Spectroscopy of biological systems

Activités / CV

Nitrogen(II) Oxide Charge Transfer Complexes on TiO2: A New Source for Visible-Light Activity

Reaction pathway for the photocatalytic oxidation of NO

Atmospheric pollution is a serious concern of society which is affecting living beings across the globe. Semiconductor photocatalysis has emerged as a very efficient and inexpensive technique to address this problem. Among the different semiconductor materials, titanium dioxide (TiO2) is recognized as one of the most powerful photocatalysts and is often used for the purpose of air purification due to its strong oxidative ability and nontoxicity. Nevertheless, due to its wide band gap of 3.2 eV, TiO2 absorbs only a small fraction of sunlight. Nitrogen oxides are among the most harmful atmospheric pollutant gases emitted by combustion, e.g., in stationary power (mainly coal) plants and automobile engines. There is, therefore, a great interest in reducing the concentration of these dangerous environmental pollutants.

Visualization of electron (orange) and hole (blue) states involved in the electronic transition

Recently, experimentalists at the University of Hannover in Germany lead by Detlef Bahnemann teamed up with the theory group of Thomas Niehaus to unravel the photodecomposition of NO on TiO2 surfaces under visible light illumination. Individually, TiO2 and NO do not absorb in the visible, while the complex experimentally shows photocatalytic activity. Theoretical simulations at the level of Time-dependent Density Functional Theory indeed revealed a absorption band in the yellow-green spectral region which corresponds to a electronic transition from the NO molecule to the semiconductor surface. This excitation weakens the N-Ti surface bond and triggers the cleavage of the NO+ ion from the surface. Based on these results, the research team proposed a new reaction pathway for the photocatalytic oxidation of NO.

Citation : Freitag, J., Dominguez, A., Niehaus, Thomas A., Huelsewig, A. , Dillert, R., Frauenheim, T. and Bahnemann, D. W.
Nitrogen(II) Oxide Charge Transfer Complexes on TiO2: A New Source for Visible-Light Activity.
J Phys. Chem. C 119, p. 4488. (2015)


About him:

Thomas Niehaus received the Ph.D. (Dr. rer. nat.) degree in physics from the University of Paderborn, Germany in 2001. After heading a research group at the Bremen Center for Computational Materials Science in Germany from 2006 to 2010, he received a call to the University of Regensburg as Professor for theoretical physics. In 2015 he moved to the Institut Lumière Matière at the Université Claude Bernard Lyon 1. He is working on large-scale first principles simulations of optoelectronic and energy conversion materials, with a recent focus on 2-D materials.

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