Intercalation based electrode materials for Fluoride Ion Batteries
 O. Clemens, C. Rongeat, M. A. Reddy, A. Giehr, M. Fichtner, H. Hahn, Dalton Transactions 2014, 43, 15771-15778.
 M. A. Nowroozi, B. de Laune, O. Clemens, ChemistryOpen 2018, 7, 617-623.
 M. A. Nowroozi, K. Wissel, J. Rohrer, A. R. Munnangi, O. Clemens, Chemistry of Materials 2017, 29, 3441-3453.
4] M. A. Nowroozi, O. Clemens, ACS Applied Energy Materials 2018, 1, 6626-6637.
 M. A. Nowroozi, S. Ivlev, J. Rohrer, O. Clemens, Journal of Materials Chemistry A 2018, 6, 4658-4669.
Topochemical Fluorination and Defluorination of Oxide Materials – Targeting Material Properties
In our group we investigate ways to make new compounds and to study them for their resulting properties. One such route was found in combining subsequent topochemical substitutive fluorination (1 oxide for 2 fluoride ions) [1-3] and reductive defluorination, which has provided a way to prepare new reduced titanates at temperatures as low as 300 °C , and we have now extended our studies to target the structural and magnetic properties of Ni-based Ruddlesden-Popper type phases .
In addition, we aim to exploit electrochemical fluorination/defluorination reactions within Fluoride Ion Battery cells to reversibly change magnetic properties of this material class, which cannot be reversibly targeted by alkali ion batteries (lithium or sodium) otherwise.
 O. Clemens, F. J. Berry, A. J. Wright, K. S. Knight, J. M. Perez-Mato, J. M. Igartua, P. R. Slater, Journal of Solid State Chemistry 2013, 206, 158-169.
 O. Clemens, P. R. Slater, Reviews in Inorganic Chemistry 2013, 33, 105-117.
 O. Clemens, R. Kruk, E. A. Patterson, C. Loho, C. Reitz, A. J. Wright, K. S. Knight, H. Hahn, P. R. Slater, Inorganic Chemistry 2014, 53, 12572-12583.
 K. Wissel, S. Dasgupta, A. Benes, R. Schoch, M. Bauer, R. Witte, A. D. Fortes, E. Erdem, J. Rohrer, O. Clemens, Journal of Materials Chemistry A 2018, 6, 22013-22026.
 K. Wissel, J. Heldt, P. B. Groszewicz, S. Dasgupta, H. Breitzke, M. Donzelli, A. I. Waidha, A. D. Fortes, J. Rohrer, P. R. Slater, G. Buntkowsky, O. Clemens, Inorganic Chemistry 2018, 57, 6549-6560.
New proton and electron conducting perovskites for protonic ceramic fuel cells
In this context, we combine studies of variable temperature X-ray and neutron diffraction, thermal analysis, impedance spectroscopy as well as FT-IR to gain understanding of the factors which help to stabilize protonic charge carriers in a Ba-rich perovskite matrix. Recently, we have moved to understand their catalytic properties for alkaline fuel cells in addition.
 O. Clemens, M. Groeting, R. Witte, J. Manuel Perez-Mato, C. Loho, F. J. Berry, R. Kruk, K. S. Knight, A. J. Wright, H. Hahn, P. R. Slater, Inorganic Chemistry 2014, 53, 5911-5921.
 A. I. Waidha, H. Zhang, M. Lepple, S. Dasgupta, L. Alff, P. Slater, A. D. Fortes, O. Clemens, Chem Commun 2019, 55, 2920-2923.
 P. L. Knoechel, P. J. Keenan, C. Loho, C. Reitz, R. Witte, K. S. Knight, A. J. Wright, H. Hahn, P. R. Slater, O. Clemens, Journal of Materials Chemistry a 2016, 4, 3415-3430.
 A. I. Waidha, M. Lepple, K. Wissel, A. Benes, S. Wollstadt, P. R. Slater, A. D. Fortes, O. Clemens, Dalton Transactions 2018, 47, 11136-11145.
Topochemical modifications of thin film compounds
Therefore, we have used methods to topochemically fluorinate  and hydrate [2,3] epitaxially grown thin films. These can then be studied as a model system representing the grain-boundary free, single-crystalline state in order to understand electrical and magnetic properties of the bulk state in a more profound way. In addition, a combination of strain engineering  and topochemical reactions might serve to induce properties which deviate from the unstrained state.
 P. A. Sukkurji, A. Molinari, C. Reitz, R. Witte, C. Kuebel, V. S. K. Chakravadhanula, R. Kruk, O. Clemens, Materials 2018, 11, 1204.
 P. A. Sukkurji, A. Molinari, A. Benes, C. Loho, V. S. K. Chakravadhanula, S. K. Garlapati, R. Kruk, O. Clemens, Journal of Physics D-Applied Physics 2017, 50, 115302.
 A. Benes, A. Molinari, R. Witte, R. Kruk, J. Broetz, R. Chellali, H. Hahn, O. Clemens, Materials 2018, 11, 52.
 O. Clemens, N. Kunkel, Nachrichten aus der Chemie 2019, 67, 59-62.
Magnetic properties of manganese vanadates
 O. Clemens, A.J. Wright, K.S. Knight, P.R. Slater, Dalton Trans. 42 (2013) 7894-7900.
2] O. Clemens, J. Rohrer, G. Nenert, Dalton Trans. 45 (2016) 156-171.