Werner Paulus

University of Montpellier

Werner Paulus

E-mail : 

Phone :  +33 467144559

  1. Career
  2. Working Fields
  3. Assisted Mechanisms for Oxygen Ionic conduction in non-Stoichiometric oxides
  4. Structural-induced electronic complexity controlled by low temperature topotactic reactions
  5. CaFeO2.5 analogous Brownmillerites prospecting replacement of ceria-based materials for heterogeneous Catalysis
  6. Selected Publications

Career

Prof. Dr. Werner Paulus is a full professor (PREX) at the Institut Charles Gerhardt at the University of Montpellier.

1991: Post-Doc at the Laboratoire Leon Brillouin, CEA Saclay (France)
1991-98: Scientific responsible of the hot neutron 4-cycle diffractometer, LLB, CEA Saclay  
1998 - 2011: Professor in Chemistry at the University of Rennes 1, France
2011 – now: Professor at the University of Montpellier, France
 
Teaching administration
2000 – 2011 responsible “Magistère Matériaux” @ University of Rennes 1
2007 - 2011 responsible Mamaself Master @ University of Rennes 1
2011 – now responsible Mamaself Master @ University of Montpellier

 

Working Fields

  • Non stoichiometric oxides, low-T reactivity of solids, materials for energy storage and transformation
  • Main methods used: neutron and X-Ray (laboratory and synchrotron) diffraction
  • In situ studies in specially designed reaction cells, 18O/16O isotope exchange reactions

Assisted Mechanisms for Oxygen Ionic conduction in non-Stoichiometric oxides

 

Understanding, at the atomic scale, the mechanisms of oxygen diffusion in solid oxides is an important issue for the development of technological devices such as solid oxide fuel cells (SOFC, including the next generation of oxide ion solid electrolytes and electrodes), as well as membrane based air separators, oxygen sensors and, last but not least, catalytic converters to transform e.g. NOx or CO from exhaust emissions into N2 and CO2. This project aims to explore low-T oxygen diffusion mechanisms by X/n-diffraction, combined with lattice dynamical simulations and spectroscopic investigations.Assisted Mechanisms for Oxygen Ionic conduction in non-Stoichiometric oxides (ANR project in collaboration with the ICMCB Bordeaux, 400 K€)

 

Understanding, at the atomic scale, the mechanisms of oxygen diffusion in solid oxides is an important issue for the development of technological devices such as solid oxide fuel cells (SOFC, including the next generation of oxide ion solid electrolytes and electrodes), as well as membrane based air separators, oxygen sensors and, last but not least, catalytic converters to transform e.g. NOx or CO from exhaust emissions into N2 and CO2. This project aims to explore low-T oxygen diffusion mechanisms by X/n-diffraction, combined with lattice dynamical simulations and spectroscopic investigations.
 

Structural-induced electronic complexity controlled by low temperature topotactic reactions

Electronic and structural correlations can be largely modulated by cation substitution and associated changes in the valence states of the transition metal. Compared to A-cation substitution, oxygen intercalation/desintercalation reactions, which proceed at ambient temperature, thus far away from thermodynamical equilibrium, are an alternative method to control the degree of oxidation of the transition metal. Controlled oxygen doping via electrochemical methods leads to the generation of a variety of long-range electronically ordered states, ranging from charge and orbital ordering to charged stripes and magnetic ordering. This project aims to explore structural and electronic complexity in Transition Metal Oxides with oxygen/hole-doping using diffraction and spectroscopic studies mainly at large scale facilities.

In situ cell mounted on BM01@ESRF, allowing to investigate chemical reactions on single crystals via electrochemical or gas-solid reaction conditions
 

CaFeO2.5 analogous Brownmillerites prospecting replacement of ceria-based materials for heterogeneous Catalysis

Project in collaboration with Saint Gobain CREE

The present project is dedicated to industrial research for the development of innovative catalytic systems for air purification, such as those used for the control of road vehicle emission (three way converter, TWC). In the context of Europe’s dependency on imports of some critical elements currently used as catalyst support (e.g. cerium oxide), we focus on more available elements such as Ca, Fe, Ti, Sr, Cu… by keeping the well-understood mechanisms governing the catalytic activity of cerium oxide in mind. As such, we choose oxygen ion conductors of the Brownmillerite family as support material, because it has been reported that lattice oxygen atoms have a beneficial impact on the catalytic activity of oxidation reactions. Next to the pure support material, also the interaction of a noble metal with the oxygen ion conductive support for the efficient removal of gas phase pollutants will be studied. In terms of catalytic reactions, the oxidation of CO, and the storage and reduction of NOx will be the primary metrics

Selected Publications

  • Solid-state reactivity explored in situ by synchrotron radiation on single crystals: from SrFeO2.5 to SrFeO3 via electrochemical oxygen intercalation, A. Maity, B. Penkala, R. Dutta, M. Ceretti, A. Lebranchu, D. Chernyshov, A. Perichon, A. Piovano, A. Bossak, M. Meven, W. Paulus, J Physics D: Applied Physics, Special issue: 100 years of crystallography: new dimensions offered by large scale facilities, J. Phys. D: Appl. Phys. 48 (2015), doi:10.1088/0022-3727/48/50/504004
  • Low temperature oxygen diffusion mechanisms in Nd2NiO4+∂ and Pr2NiO4+∂ via large anharmonic displacements, explored by single crystal neutron diffraction, M. Ceretti, O. Wahyudi, A. Cousson, A. Villesuzanne, M. Meven, B. Pedersen, J.-M. Bassat, W. Paulus, JOURNAL OF MATERIALS CHEMISTRY A, 3, 42 (2015) p21140-48, DOI: 10.1039/c5ta05767a
  • One-dimensional oxygen diffusion mechanism in Sr2ScGaO5 electrolyte explored by neutron and synchrotron diffraction, 17O-NMR and DFT calculations, Serena Corallini Monica Ceretti, Gilles Silly, Andrea Piovano, Shubra Singh, Josef Stern, Clemens Ritter, Jinjun Ren, Hellmut Eckert, Kazimirz Conder, Wei-tin Chen, Fang-Cheng Chou, Noriya Ichikawa, Yuichi Shimakawa, Werner Paulus, J. Phys. Chem. C, 2015, 119 (21), pp 11447–11458 DOI: 10.1021/acs.jpcc.5b02173
  • Role of Lattice Oxygen on CO Oxidation Over Ce18O2-Based Catalyst Revealed Under Operando Conditions, Bartosz Penkala, Daniel Aubert, Helena Kaper, Caroline Tardivat, Kazimierz Conder and Werner Paulus, Catalysis Science & Technology, 2015, 5, 4839-4848, DOI: 10.1039/C5CY00842E
  • From T to T’-La2CuO4 via Oxygen Vacancy Ordered La2CuO3.5”, M. Ikbel Houchati, M. Ceretti, C. Ritter and W. Paulus, Chem. Mater. 2012, 24, 3811-3815 , DOI: 10.1021/cm302485q