@article{BurekKrauseSchwotzeretal.2018, author = {Burek, Katja and Krause, Felix and Schwotzer, Matthias and Nefedov, Alexei and S{\"u}ssmuth, Julia and Haubitz, Toni and Kumke, Michael Uwe and Thissen, Peter}, title = {Hydrophobic Properties of Calcium-Silicate Hydrates Doped with Rare-Earth Elements}, series = {ACS sustainable chemistry \& engineering}, volume = {6}, journal = {ACS sustainable chemistry \& engineering}, number = {11}, publisher = {American Chemical Society}, address = {Washington}, issn = {2168-0485}, doi = {10.1021/acssuschemeng.8b03244}, pages = {14669 -- 14678}, year = {2018}, abstract = {In this study, the apparent relationship between the transport process and the surface chemistry of the Calcium-Silicate Hydrate (CSH) phases was investigated. For this purpose, a method was developed to synthesize ultrathin CSH phases to be used as a model substrate with the specific modification of their structure by introducing europium (Eu(III)). The structural and chemical changes during this Eu(III)-doping were observed by means of infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), and time-resolved laser fluorescence spectroscopy (TRLFS). These alterations of the CSH phases led to significant changes in the surface chemistry and consequently to considerable variations in the interaction with water, as evidenced by measurements of the contact angles on the modified model substrates. Our results provide the basis for a more profound molecular understanding of reactive transport processes in cement-based systems. Furthermore, these results broaden the perspective of improving the stability of cement-based materials, which are subjected to the impact of aggressive aqueous environments through targeted modifications of the CSH phases.}, language = {en} } @article{LangeReiterPaetzeletal.2014, author = {Lange, Ilja and Reiter, Sina and Paetzel, Michael and Zykov, Anton and Nefedov, Alexei and Hildebrandt, Jana and Hecht, Stefan and Kowarik, Stefan and Woell, Christof and Heimel, Georg and Neher, Dieter}, title = {Tuning the work function of polar zinc oxide surfaces using modified phosphonic acid self-assembled monolayers}, series = {Advanced functional materials}, volume = {24}, journal = {Advanced functional materials}, number = {44}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1616-301X}, doi = {10.1002/adfm.201401493}, pages = {7014 -- 7024}, year = {2014}, abstract = {Zinc oxide (ZnO) is regarded as a promising alternative material for transparent conductive electrodes in optoelectronic devices. However, ZnO suffers from poor chemical stability. ZnO also has a moderate work function (WF), which results in substantial charge injection barriers into common (organic) semiconductors that constitute the active layer in a device. Controlling and tuning the ZnO WF is therefore necessary but challenging. Here, a variety of phosphonic acid based self-assembled monolayers (SAMs) deposited on ZnO surfaces are investigated. It is demonstrated that they allow the tuning the WF over a wide range of more than 1.5 eV, thus enabling the use of ZnO as both the hole-injecting and electron-injecting contact. The modified ZnO surfaces are characterized using a number of complementary techniques, demonstrating that the preparation protocol yields dense, well-defined molecular monolayers.}, language = {en} }