Andriy Borodin
Clausthal University of Technology
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Andriy Borodin.
Physical Chemistry Chemical Physics | 2011
Andriy Borodin; Michael Reichling
The unreconstructed TiO(2)(110) surface is prepared in well-defined states having different characteristic stoichiometries, namely reduced (r-TiO(2), 6 to 9% surface vacancies), hydroxylated (h-TiO(2), vacancies filled with OH), oxygen covered (ox-TiO(2), oxygen adatoms on a stoichiometric surface) and quasi-stoichiometric (qs-TiO(2), a stoichiometric surface with very few defects). The electronic structure and work function of these surfaces and transition states between them are investigated by ultraviolet photoelectron spectroscopy (UPS) and metastable impact electron spectroscopy (MIES). The character of the surface is associated with a specific value of the work function that varies from 4.9 eV for h-TiO(2), 5.2 eV for r-TiO(2), 5.35 eV for ox-TiO(2) to 5.5 eV for qs-TiO(2). We establish the method for an unambiguous characterization of TiO(2)(110) surface states solely based on the secondary electron emission characteristics. This is facilitated by analysing a weak electron emission below the nominal work function energy. The emission in the low energy cut-off region appears correlated with band gap emission found in UPS spectra and is attributed to localised electron emission through Ti(3+)(3d) states.
Physical Chemistry Chemical Physics | 2005
Francesc Viñes; Andriy Borodin; Oliver Höfft; V. Kempter; Francesc Illas
The activation of CO2 by interaction with Na atoms on tungsten was studied in a joint experimental/theoretical effort combining MIES, UPS (HeII) and first principles calculations. Experimentally, both the adsorption of Na on tungsten, followed by CO2 exposure to the Na-modified surface at 80 K, and the adsorption of CO2 on tungsten, followed by Na exposure to the CO2 covered substrate, were studied. Below about 120 K CO2 physisorbs on pure W(011), and the distance between the three main spectral features is as for gas phase CO2 (E(B) = 8.4, 12.1, 14.1 eV). When offered to a Na monolayer (ML) deposited onto W, CO2 is converted into a chemisorbed species. The spectral pattern is different from physisorbed CO2, and the three spectral features are shifted towards lower binding energies (E(B) = 6.3, 10.7, 13.9 eV). The chemisorption continues until all available Na species are converted into Na+ species. Additional CO2 offered to the system becomes physisorbed on top of the chemisorbed species. When a CO2 monolayer, physisorbed on tungsten at 80 K, is exposed to Na, the interaction leads initially to a decrease of the surface work function and to a rigid, global shift of all CO2 induced features towards larger binding energies by about 2 eV. Only beyond a minimum Na coverage of about 0.5 ML, chemisorbed species can be detected. We conclude that, initially, transfer of the Na(3s) electron to the tungsten substrate takes place. Above 0.5 ML Na coverage, back donation of charge to CO2 takes place whereby the physisorbed carbon dioxide species become converted into chemisorbed ones. The experimental results are interpreted with the help of first principle calculations carried out on suitable slab models. The structures and surface binding mode of the chemisorbed CO2 species are described. The calculated density of states for the most stable situations is in qualitative agreement with experimental data.
Journal of Physical Chemistry Letters | 2018
Zhen Liu; Guozhu Li; Andriy Borodin; Xiaoxu Liu; Yao Li; Frank Endres
Investigations of the solid-electrolyte interphase formation on a silicon anode are of great interest for future lithium-ion batteries. We have studied the interactions of the ionic liquid 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl) amide ([OMIm]Tf2N) and of lithium with Si(111) surfaces on a molecular level by X-ray photoelectron spectroscopy. The interaction of Li with [OMIm]Tf2N on Si(111) results in the decomposition of both the cation and the anion and the intercalation of lithium. Lithium atoms donate the electrons to the [OMIm]+ cation, forming Li+, and at the same time the alkyl group is detached from the cation. Excessive Li could decompose the imidazolium ring, resulting in C xH y and LiC xH yN z species and interact with the Tf2N- anions, forming LiF, Li xO, F3C-O2S-N-Li+, and F3C-O2S-Li+ species. The formation of a stable Si/IL interface and of Si/Li surface alloys was proved to be an effective strategy in stabilizing Li for next-generation Li-ion batteries.
Chemistry-an Asian Journal | 2017
Giridhar Pulletikurthi; Bernd Weidenfeller; Andriy Borodin; Jan C Namyslo; Frank Endres
Electrostatic interactions are characteristic of ionic liquids (ILs) and play a pivotal role in determining the formation of species when solutes are dissolved in them. The formation of new species/complexes has been investigated for certain ILs. However, such investigations have not yet focused on eutectic liquids, which are a promising class of ILs. These liquids (or liquid coordination complexes, LCCs) are rather new and are composed of cationic and anionic chloro complexes of metals. To date, these liquids have been employed as electrolytes to deposit metals and as solvents for catalysis. The present study deals with a liquid that is prepared by mixing a 1.2:1 mol ratio of AlCl3 and 1-butylpyrrolidine. An attempt has been made to understand the interactions of FeCl2 with the organic molecule using spectroscopy. It was found that dissolved Fe(II) species interact mainly with the IL anion and such interactions can lead to changes in the cation of the electrolyte. Furthermore, the viability of depositing thick magnetic films of Fe and Fe-Al has been explored.
Progress in Natural Science: Materials International | 2015
Giridhar Pulletikurthi; Björn Bödecker; Andriy Borodin; Bernd Weidenfeller; Frank Endres
Physical Chemistry Chemical Physics | 2016
Abhishek Lahiri; Natalia Borisenko; Andriy Borodin; Mark Olschewski; Frank Endres
Chemical Communications | 2014
Abhishek Lahiri; Natalia Borisenko; Andriy Borodin; Frank Endres
Dalton Transactions | 2017
Giridhar Pulletikurthi; Maryam Shapouri Ghazvini; Tong Cui; Natalia Borisenko; Timo Carstens; Andriy Borodin; Frank Endres
Journal of Solid State Electrochemistry | 2018
Zhen Liu; Guozhu Li; Tong Cui; Andriy Borodin; Chantal Kuhl; Frank Endres
Physical Chemistry Chemical Physics | 2018
Viktor Hoffmann; Giridhar Pulletikurthi; Timo Carstens; Abhishek Lahiri; Andriy Borodin; Max Schammer; Birger Horstmann; Arnulf Latz; Frank Endres