Inst. Chemie

859 Items

Recent Submissions
Experimental Activity Descriptors for Iridium-based Catalysts for the Electrochemical Oxygen Evolution Reaction (OER)

Spöri, Camillo Wolfgang ; Briois, Pascal ; Nong, Hong Nhan ; Reier, Tobias ; Billard, Alain ; Kühl, Stefanie ; Teschner, Detre ; Strasser, Peter (2019-06-13)

Recent progress in the activity improvement of anode catalysts for acidic electrochemical water splitting was largely achieved through empirical studies of iridium-based bimetallic oxides. However, practical, experimentally accessible, yet general predictors of catalytic OER activity are lacking. This study investigates iridium and iridium-nickel thin film model electrocatalysts for the OER and...

The Stability Challenges of Oxygen Evolving Catalysts: Towards a Common Fundamental Understanding and Mitigation of Catalyst Degradation

Spöri, Camillo Wolfgang ; Kwan, Jason Tai Hong ; Bonakdarpour, Arman ; Wilkinson, David P. ; Strasser, Peter (2017-05-04)

This review addresses the technical challenges, their scientific basis, as well as recent progress and the road ahead with respect to the stability and degradation of OER catalysts operating at electrolyzer anodes in acidic environments with an emphasis on MEA based operation. First, we start clarifying the complexity associated with the term “catalyst stability”, cover today’s performance targ...

Kinetic study of dry reforming of Methane with Ni over different supports and Pt/Al2O3

Guan, Chengyue (2019)

This thesis presents a kinetic study on Ni series catalysts for dry reforming of methane (DRM) and comparison with a commercially noble metal catalyst Pt/Al2O3. For each catalyst, a corresponding kinetic model needs to be established. These kinetic schemes should be sophisticated enough to describe the consumption rates, meanwhile rather simple for industrial applications. In this thesis, we in...

Direct utilization of methane: from mechanism understanding to process optimization

Parishan, Samira (2019)

Methane, which is a promising alternative to replace crude oil, is currently underutilized. Industrialization of either OCM or DMTM could realize utilization of methane to value-added chemicals. But, unfortunately, none of these reactions have still an industrially acceptable yield. In this thesis, it was searched for the solutions to overcome these yield barriers. The focus in the OCM projec...

Structural Dynamics of Spin Crossover in Iron(II) Complexes with Extended-Tripod Ligands

Stock, Philipp ; Wiedemann, Dennis ; Petzold, Holm ; Hörner, Gerald (2017-09-05)

Selective manipulation of spin states in iron(II) complexes by thermal or photonic energy is a desirable goal in the context of developing molecular functional materials. As dynamic spin-state equilibration in isolated iron(II) complexes typically limits the lifetime of a given spin state to nanoseconds, synthetic strategies need to be developed that aim at inhibited relaxation. Herein we show ...

Synthese und Anwendung kationischer bor- und phosphorbasierter LEWIS-Säurekatalysatoren

Vogler, Maria (2019)

Die vorliegende Arbeit widmet sich zum einen der Synthese und Anwendung neuer axial chiraler Boreniumkationen und zum anderen der Anwendung verschiedener achiraler Phosphoniumkationen in DIELS–ALDER-Reaktionen und NAZAROV-Cyclisierungen. Für chirale Boreniumkationen und deren Anwendung als LEWIS-Säurekatalysatoren gibt es bisher nur vereinzelte Beispiele mit eher niedrigen Enantiomerenüberschü...

Geometrie, Spinzustand und Reaktivität verzerrt-oktaedrischer Eisen-Komplexe im Lichte des Liganddesigns

Kroll, Nicole (2019)

Im Rahmen dieser Arbeit wurden drei Themenbereiche, die sich mit dem Einfluss der Ligandumgebung von pentadentaten Liganden auf die Geometrie, den Spinzustand und die Reaktivität von Eisen-Komplexen befassen, bearbeitet. Einerseits konnte der isolierte Einfluss der Donoratome auf die Ligandumgebung und damit auf die Struktur der Chelatkomplexe eindeutig gezeigt werden. Dazu wurde der Ligand TPS...

Surface Patterning of Gold Nanoparticles on PEG-Based Hydrogels to Control Cell Adhesion

Ren, Fang ; Yesildag, Cigdem ; Zhang, Zhenfang ; Lensen, Marga C. (2017-04-26)

We report on a versatile and easy approach to micro-pattern gold nanoparticles (Au NPs) on 8-arm poly(ethylene glycol)-vinyl sulfone thiol (8PEG-VS-SH) hydrogels, and the application of these patterned Au NPs stripes in controlling cell adhesion. Firstly, the Au NPs were patterned on silicon wafers, and then they were transferred onto reactive, multifunctional 8PEG-VS-SH hydrogels. The patterne...

Droplets, Evaporation and a Superhydrophobic Surface: Simple Tools for Guiding Colloidal Particles into Complex Materials

Sperling, Marcel ; Gradzielski, Michael (2017-05-04)

The formation of complexly structured and shaped supraparticles can be achieved by evaporation-induced self-assembly (EISA) starting from colloidal dispersions deposited on a solid surface; often a superhydrophobic one. This versatile and interesting approach allows for generating rather complex particles with corresponding functionality in a simple and scalable fashion. The versatility is base...

Surface Plasmon Resonance Immunosensor for the Detection of Campylobacter jejuni

Masdor, Noor Azlina ; Altintas, Zeynep ; Tothill, Ibtisam E. (2017-05-16)

Campylobacteriosis is an internationally important foodborne disease caused by Campylobacter jejuni. The bacterium is prevalent in chicken meat and it is estimated that as much as 90% of chicken meat on the market may be contaminated with the bacterium. The current gold standard for the detection of C. jejuni is the culturing method, which takes at least 48 h to confirm the presence of the bact...

Volume Hologram Formation in SU-8 Photoresist

Sabel, Tina (2017-05-30)

In order to further understand the mechanism of volume hologram formation in photosensitive polymers, light-induced material response is analyzed in commonly used epoxy-based negative photoresist Epon SU-8. For this purpose, time-resolved investigation of volume holographic grating growth is performed in the SU-8 based host–guest system and in the pure SU-8 material, respectively. The compariso...

Metal-catalyzed radical C(sp3)–Si/Ge cross-coupling reactions

Xue, Weichao (2019)

This thesis is dedicated to the development of transition-metal catalyzed C(sp3)–Si cross-coupling reactions of silicon and germanium (pro)nucleophilles with alkyl electrophiles, thereby enabling the efficient synthesis of alkyl substituted silanes and germanes. The first part looks into copper-catalyzed cross-coupling reactions of Si–B reagents with a variety of redox-active alkyl electrophil...

A facile approach to bimetallic supported catalysts using preorganized molecular single-source precursors

Linke, Stephanie Sybille (2019)

Aim of this work was the development of a purposeful bottom-up synthesis route towards supported polymetallic alloy catalysts, allowing precise control over stoichiometry and mixing pattern of the respective metals on the support, and being applicable even towards metals with thermodynamically unfavorable mixing behavior. Thus, the single-source precursor (SSP) approach was developed, making us...

Structure-stability-activity studies on low Ir content mixed metal oxides for the electrochemical water oxidation in acidic media

Spöri, Camillo Wolfgang (2019)

Today, renewable energy power plants are being installed on an increasing scale, however, their growing capacity calls for reliable high-performance storage technologies to be developed simultaneously. PEM water electrolysis is one of the key emerging technologies for chemical energy storage in form of hydrogen, which, for example, can be used in fuel cells for transportation and reconversion t...

Amorphous outperforms crystalline nanomaterials: surface modifications of molecularly derived CoP electro(pre)catalysts for efficient water-splitting

Beltrán-Suito, Rodrigo ; Menezes, Prashanth W. ; Drieß, Matthias (2019-06-04)

The single source precursor (SSP) approach was used to prepare highly active CoP bifunctional electro(pre)catalysts for the oxygen evolution reaction (OER), hydrogen evolution reaction (HER) and overall water splitting (OWS) reaction starting from a molecular β-diketiminato Co(I) cyclo-P4 complex. Crystalline or amorphous CoP particles were attained depending on the preparation route. Notably, ...

Untersuchung von Deflagrationen selbstzersetzlicher Feststoffe und Entwicklung einer neuartigen Prüfmethode zur Beurteilung der Deflagrationsfähigkeit in geschlossenen Systemen

Salg, Steffen (2019)

Das Deflagrationsverhalten selbstzersetzlicher fester Stoffe wurde bei unterschiedlichen Randbedingungen untersucht. Darüber hinaus wurde eine neue Prüfmethode entwickelt, mit welcher das Deflagrationsverhalten in geschlossenen Systemen beurteilt werden kann. Es wurden drei neue Messsysteme mit verschiedenen Volumina und Geometrien im Labormaßstab in Betrieb genommen. Die Verwendung der neuen M...

The role of local and remote amino acid substitutions for optimizing fluorescence in bacteriophytochromes: A case study on iRFP

Buhrke, David ; Velazquez Escobar, Francisco ; Sauthof, Luisa ; Wilkening, Svea ; Herder, Nico ; Tavraz, Neslihan N. ; Willoweit, Mario ; Keidel, Anke ; Utesch, Tillmann ; Mroginski, Maria-Andrea ; Schmitt, Franz-Josef ; Hildebrandt, Peter ; Friedrich, Thomas (2016-06-22)

Bacteriophytochromes are promising tools for tissue microscopy and imaging due to their fluorescence in the near-infrared region. These applications require optimization of the originally low fluorescence quantum yields via genetic engineering. Factors that favour fluorescence over other non-radiative excited state decay channels are yet poorly understood. In this work we employed resonance Ram...

Investigating silica nanoparticles/polymer composites

Perrin, Elsa (2019)

Polymer / silica interface is investigated using coarse-grained molecular dynamics simulations. In particular, the different behavior of poly(acrylamide) (PAAm) and of poly(N,Ndimethylacrylamide) (PDMA) on the silica surface is compared. First, we show that the macroscopic behavior of PAAm and of PDMA are correctly represented by a model containing an explicit solvent. Then, the umbrella sampli...

Metal-nitrogen-doped carbon (M-N-C) catalysts for the direct electrochemical reduction of CO2 to value-added chemicals and fuels

Ju, Wen (2019)

In the past decades, the surplus of atmospheric CO2 concentration has drawn tremendous political and scientific attention for its negative impacts, such as the greenhouse effect and ocean carbonation. To mitigate such CO2 issues, a combination of various strategies is required. The electrochemical CO2 reduction reaction (CO2RR) is a promising alternative to convert CO2 into carbon-based chemica...

Model-system studies on manganese oxide-based water oxidation catalysts made with atomic layer deposition

Plate, Paul (2019)

Climate change has become the main challenge of our society. Extensive CO2 emission due to fossil fuel combustion has to be minimized to prevent severe damages to the climate system. Hence, new and sustainable energy carriers have to be explored. Hydrogen can be produced in a sustainable manner, however, current processes are not yet economically viable. Photoelectrochemical water splitting is ...