Inst. Chemie

976 Items

Recent Submissions
Light-induced phase transition of gold-microgel hybrids

Lehmann, Maren (2020)

The aim of this thesis was the development and characterisation of a hybrid system based on poly(N-isopropylacrylamide) (PNIPAM) microgels and spherical gold nanoparticles (AuNPs), which undergoes a reversible photo-thermal volume phase transition (VPT). In order to understand the relationship between the microgel properties and the stimuli-responsive behaviour of AuNP-microgel hybrid particle...

Cobalt‐Exchanged Poly(Heptazine Imides) as Transition Metal–Nx Electrocatalysts for the Oxygen Evolution Reaction

Ye, Meng‐Yang ; Li, Shuang ; Zhao, Xiaojia ; Tarakina, Nadezda V. ; Teutloff, Christian ; Chow, Wing Ying ; Bittl, Robert ; Thomas, Arne (2020-01-27)

Poly(heptazine imides) hosting cobalt ions as countercations are presented as promising electrocatalysts for the oxygen evolution reaction (OER). A facile mixed‐salt melt‐assisted condensation is developed to prepare such cobalt poly(heptazine imides) (PHI‐Co). The Co ions can be introduced in well‐controlled amounts using this method, and are shown to be atomically dispersed within the imide‐l...

Techno-economic assessment – methodology development and the case of CO2-containing polyurethane rubbers

Buchner, Georg Alexander (2020)

Well-founded project decisions on the continuation of research, development, and deployment (RD&D) activities are crucial to the success of an economic entity. Decision-makers rely heavily on sound techno-economic assessment (TEA), a systematic approach for judging the economic viability of a technology. A multitude of individual technology characteristics and practitioners’ backgrounds result ...

A comparative perspective of electrochemical and photochemical approaches for catalytic H2O2 production

Sun, Yanyan ; Han, Lei ; Strasser, Peter (2020-08-06)

Hydrogen peroxide (H2O2) has a wide range of important applications in various fields including chemical industry, environmental remediation, and sustainable energy conversion/storage. Nevertheless, the stark disconnect between today's huge market demand and the historical unsustainability of the currently-used industrial anthraquinone-based production process is promoting extensive research on...

H2 as a fuel for flavin- and H2O2-dependent biocatalytic reactions

Al-Shameri, Ammar ; Willot, Sébastien J.-P. ; Paul, Caroline E. ; Hollmann, Frank ; Lauterbach, Lars (2020-07-14)

The soluble hydrogenase from Ralstonia eutropha provides an atom efficient regeneration system for reduced flavin cofactors using H2 as an electron source. We demonstrated this system for highly selective ene-reductase-catalyzed C[double bond, length as m-dash]C-double bond reductions and monooxygenase-catalyzed epoxidation. Reactions were expanded to aerobic conditions to supply H2O2 for perox...

Establishing reactivity descriptors for platinum group metal (PGM)-free Fe–N–C catalysts for PEM fuel cells

Primbs, Mathias ; Sun, Yanyan ; Roy, Aaron ; Malko, Daniel ; Mehmood, Asad ; Sougrati, Moulay-Tahar ; Blanchard, Pierre-Yves ; Granozzi, Gaetano ; Kosmala, Tomasz ; Daniel, Giorgia ; Atanassov, Plamen ; Sharman, Jonathan ; Durante, Christian ; Kucernak, Anthony ; Jones, Deborah ; Jaouen, Frédéric ; Strasser, Peter (2020-06-24)

We report a comprehensive analysis of the catalytic oxygen reduction reaction (ORR) reactivity of four of today's most active benchmark platinum group metal-free (PGM-free) iron/nitrogen doped carbon electrocatalysts (Fe–N–Cs). Our analysis reaches far beyond previous such attempts in linking kinetic performance metrics, such as electrocatalytic mass-based and surface area-based catalytic activ...

Chirale schwefelstabilisierte Siliciumkationen als Lewis-Säure-Katalysatoren für enantioselektive Diels–Alder-Reaktionen

Shaykhutdinova, Polina (2020)

Die vorliegende Dissertation ist der Synthese und Charakterisierung von chiralen schwefelstabilisierten Siliciumkationen und deren Anwendung als Lewis-Säure-Katalysatoren in enantioselektiven Diels–Alder-Reaktionen gewidmet, wobei der Schwerpunkt auf anspruchsvollen Cycloadditionen von Cyclohexa-1,3-dien und α,β-ungesättigten Carbonylverbindungen liegt. Die Erzeugung chiraler schwefelstabilisi...

Entwicklung und Charakterisierung neuartiger, chiraler Vertreter des Tetrakis(pentafluorphenyl)borats und deren Anwendung in der Katalyse

Pommerening, Phillip (2020)

Während eine Vielzahl teils hochwirksamer, chiraler Gegenanionen zur asymmetrischen Reaktionsführung bereits in der Literatur vorgestellt wurden, sind nur sehr wenige, donoratom-freie Beispiele zur Erzeugung hochelektrophiler Kationen bekannt. Die hierfür bekanntesten und am weitesten verbreiteten achiralen Vertreter sind dabei das [BArF4]–- sowie das [B(C6F5)4]–-Anion, wobei lediglich letztere...

Einfluss des Komplexbildners Pyrophosphat auf die Abscheiderate eines elektrochemischen Zinnabscheideprozesses

Tuna, Kadir (2020)

Die vorliegende Arbeit beschäftigt sich mit der elektrochemischen Zinnabscheidung und liefert ein Konzept für den Abscheidemechanismus aus pyrophosphathaltigen Bädern. Zinnbäder basierend auf dem Komplexbildner Pyrophosphat (PP) zeigten während der Beschichtung einen starken Abfall der Abscheiderate. Untersuchungen im Elektrolyten mit der Quarzmikrowaage belegten, dass Badparameter wie pH-Wert,...

Formation and characterization of complexes of oppositely charged oil-in-water (O/W) microemulsion droplets and polyelectrolytes

Simon, Miriam (2020)

Oil-in-water (O/W) microemulsion droplets are thermodynamically stable liquid systems that allow to have a rather high content of hydrophobic material dispersed in aqueous solution, which otherwise could not be dissolved. Further, microemulsion droplets have a well-defined spherical structure with low polydispersity, which renders them good model colloids. In that context, mixtures of charged m...

Structure activity correlations of coinage metals supported on SBA-15 in selective oxidation of propene

Diekmann, Marek (2020)

Coinage metals comprising copper, silver, and gold supported on SBA-15 were prepared and introduced as model catalysts in propene oxidation. The objective of this work was elucidating structure function correlations. Structural evolution and catalytic activity were investigated during selective oxidation of propene focusing on product distribution of nucleophilic and electrophilic oxidation. I...

Efficient direct seawater electrolysers using selective alkaline NiFe-LDH as OER catalyst in asymmetric electrolyte feeds

Dresp, Sören ; Thanh, Trung Ngo ; Klingenhof, Malte ; Brückner, Sven ; Hauke, Philipp ; Strasser, Peter (2020-05-20)

Direct seawater electrolysis faces fundamental catalytic and process engineering challenges. Here we demonstrate a promising seawater electrolyser configuration using asymmetric electrolyte feeds. We further investigated the faradaic O2 efficiency of NiFe-LDH in alkalinized Cl−-containing electrolytes in comparison to commercial IrOx-based catalysts. Other than IrOx, NiFe-LDH prevents the oxida...

Discovery and Characterization of a New Cold-Active Protease From an Extremophilic Bacterium via Comparative Genome Analysis and in vitro Expression

Perfumo, Amedea ; Saß, Georg Johannes Freiherr von ; Nordmann, Eva-Lena ; Budisa, Nediljko ; Wagner, Dirk (2020-05-13)

Following a screening of Antarctic glacier forefield-bacteria for novel cold-active enzymes, a psychrophilic strain Psychrobacter sp. 94-6PB was selected for further characterization of enzymatic activities. The strain produced lipases and proteases in the temperature range of 4–18°C. The coding sequence of an extracellular serine-protease was then identified via comparative analysis across Psy...

Precise Orbit and Clock Products of Galileo, BDS and QZSS from MGEX Since 2018: Comparison and PPP Validation

Li, Xingxing ; Zhu, Yiting ; Zheng, Kai ; Yuan, Yongqiang ; Liu, Gege ; Xiong, Yun (2020-04-30)

In recent years, the development of new constellations including Galileo, BeiDou Navigation Satellite System (BDS) and Quasi-Zenith Satellite System (QZSS) have undergone dramatic changes. Since January 2018, about 30 satellites of the new constellations have been launched and most of the new satellites have been included in the precise orbit and clock products provided by the Multi Global Navi...

The role of polysulfide dianions and radical anions in the chemical, physical and biological sciences, including sulfur-based batteries

Steudel, Ralf ; Chivers, Tristram (2019-05-24)

The well-known tendency of sulfur to catenate is exemplified by an extensive series of polysulfide dianions [Sn]2− (n = 2–9) and related radical monoanions [Sn]˙−. The dianions can be isolated as crystalline salts with appropriate cations and structurally and spectroscopically characterized. Although the smaller radical monoanions may be stabilized in zeolitic matrices, they are usually formed ...

Bilayer thickness determines the alignment of model polyproline helices in lipid membranes

Kubyshkin, Vladimir ; Grage, Stephan L. ; Ulrich, Anne S. ; Budisa, Nediljko (2019-09-18)

Our understanding of protein folds relies fundamentally on the set of secondary structures found in the proteomes. Yet, there also exist intriguing structures and motifs that are underrepresented in natural biopolymeric systems. One example is the polyproline II helix, which is usually considered to have a polar character and therefore does not form membrane spanning sections of membrane protei...

Activation of tetrafluoropropenes by rhodium(i) germyl and silyl complexes

Talavera, Maria ; Müller, Robert ; Ahrens, Theresia ; von Hahmann, Cortney N. ; Braun-Cula, Beatrice ; Kaupp, Martin ; Braun, Thomas (2019-09-20)

The reaction of the rhodium(I) complexes [Rh(E)(PEt3)3] (E = GePh3 (1), Si(OEt)3 (5)) with HFO-1234yf (2,3,3,3-tetrafluoropropene) afforded [Rh(F)(PEt3)3] (2) and the functionalized olefins Z-CF3CH[double bond, length as m-dash]CH(E) (E = GePh3 (4a), Si(OEt)3 (7)). Conceivable reaction pathways were assessed using DFT calculations. Reactions of [Rh(E)(PEt3)3] with HFO-1234ze (E-1,3,3,3-tetraflu...

Synthesis and characterization of Cu-based multinary metal oxides for photoelectrochemical water splitting

Song, Angang (2020)

In the future, the storage of solar energy in the form of chemical bonds is expected to be a key method for solar energy conversion. Photoelectrochemical (PEC) water splitting is one of the most important approaches to convert solar energy into chemical bonds via production of hydrogen. However, there are numerous scientific challenges in developing this PEC water splitting, including the ident...

Boron Lewis acid-catalyzed transfer reactions towards alkenes

Orecchia, Patrizio (2020)

Diese Arbeit ist der Entwicklung neuer Surrogate für Transferreaktionen von gefährlichen Chemikalien wie Diwasserstoff, Hydrosilanen und Cyanwasserstoff gewidmet, die neue Transformationen mit Alkenen ermöglichen. Der erste Teil befasst sich mit der durch Bor-LEWIS-Säuren katalysierten Transferhydrierung und Hydrosilylierung unter Verwendung neuer Surrogate auf Cyclohexa-1,3-dien-Basis. Unter ...

Differential electrochemical mass spectrometry – design, set up and application for kinetic isotope labeling studies of the electrocatalytic CO2 electroreduction

Ferreira de Araújo, Jorge Vicente (2020)

This thesis presents work on the design, set up, validation, and application of a versatile differential electrochemical mass spectrometry (DEMS) system with new cell components for use in investigations of time-resolved kinetics of electrocatalytic reactions. The newly designed and built DEMS system features an improved interface liquid vacuum for high sensitivity mass spectrum detection, coup...