This master’s thesis is focused on the subject of graphene modified with atomic hydrogen and its electronic transport properties. Structural and electronic properties of graphene and hydrogenated graphene are compared in the theoretical part of the thesis. The Raman spectroscopy technique is described, including characterization of typical Raman spectra of both unmodified and modified graphene. Samples used during experimental part of the thesis are prepared via laser and electron lithography, and are set to be measured in a vacuum chamber. Subsequently, electronic transport properties are measured before and after hydrogen modification of graphene. Finally, hydrogenated graphene is irradiated using electron beam and changes in its structure are analyzed with Raman spectroscopy techniques.

This diploma thesis deals with the concept of use of nanotechnology for cement composites and UHPC. In the theoretical part of this diploma thesis there are theoretical principles described for successful design of high performance concrete and characteristics of main feedstock and its production. Furthermore, there is a focus on nanoparticles, especially the ones with carbon base in the form of carbon nanotubes CNT, in addition to that, graphenes GN that are new on the market, moreover, graphene oxide GO and its application in cement composites to mechanical characteristics and its durability. The first part of the practical part devotes in trying to find out an optimal parameter for ultrasonic mix with a suitable surface active substance of three graphenes. The other two parts of the practical part are about influence of graphenes on mechanical characteristics, cement paste microstructure, and application in the mix of concrete C 35/45 and UHPC

This thesis focuses on the study of graphene application in electronics and technology of preparation. In addition to the basic properties of graphene, the theoretical part of the work also describes the methods of its preparation, transmission, characterization and possibilities of application in electronics. The experimental part is divided into three chapters. The first chapter deals with the production of graphene by deposition from the gaseous phase, its transmission and application in the field of solar cells. The Poly(methyl methacrylate) polymer was first used for transfer of graphene, which was later replaced by Rosin due to less contamination of graphene at the end of the transmission process. The second chapter deals with the preparation of quantum dots by exfoliation in the liquid phase from graphite and its application in voltammetry. Voltammetry was utilized in this work to detect hydrogen peroxide using a gold electrode modified by quantum dots from graphene and other dichalcogens (MoS2, MoSe2, WS2, WSe2). In the last chapter, the influence of the substrate and the deposition conditions of graphene is studied by means of a plasma-reinforced phase-out of gas to growth, while the prepared graphene was characterized by imaging and spectroscopic methods. The entire experimental growth of graphene was managed and evaluated using a planned experiment.

This diploma thesis deals with the influence of addition of carbon nanoparticles on cement composites. The theoretical part of the diploma thesis is focused on the research of information about carbon nanoparticles, more precisely about carbon nanotubes and graphene oxide. There are summarized methods of dispersing carbon nanotubes and their effects on cement composites. The practical part follows the theoretical part of the research. In the first phase, the correct technique of graphene oxide dispersion was verified. Subsequently, the effects of graphene oxide on the mechanical properties of cement mortars were verified. In the final phase of the diploma thesis, the knowledge gained from the previous part was verified on concrete samples.

Graphene and Carbon nanotubes (CNTs) have been researched for more than a decade due to their extraordinary properties and advantages towards applications like electronics, structural re-enforcements, thermal management and energy storage. Graphene-CNT hybrid structures have been predicted to further enhance the exceptional properties and overcome some of the shortcomings of the individual materials. Advantages of a structure consisting of vertically aligned carbon nanotubes (VACNTs) covalently bonded with graphene layers have been predicted to be especially favourable for applications like TIM, supercapacitors and battery electrodes. This project investigates two growth mechanisms for obtaining Graphene-VACNT structures using scalable processes. Shortcomings of previously done research on similar structures like graphene transfer and bad CNT alignment is solved. A novel growth mechanism is also investigated to set the foundation for research into a new approach to grow Graphene-CNT hybrid structures in the future. Chemical Vapor Deposition (CVD) was the method used to grow the graphene and CNT structures. The characterization was done using optical microscopy, Scanning electron microscopy (SEM) and Raman spectroscopy. / Grafen- och kolnanorör (CNT) har forskats i mer än ett decennium på grund av deras extraordinära egenskaper och fördelar gentemot applikationer som elektronik, strukturförstärkning, termisk hantering och energilagring. Grafen-CNT hybridstrukturer har förutspåtts ytterligare förbättra de exceptionella egenskaperna och övervinna några av bristerna i de enskilda materialen. Fördelar med en struktur som består av vertikalt inriktade kolnanorör (VACNT) som är kovalent bundna med grafenskikt har förutspåtts vara särskilt fördelaktiga för applikationer som TIM, superkondensatorer och batterielektroder. Detta projekt undersöker två tillväxtmekanismer för att erhålla Graphene-VACNT-strukturer med hjälp av skalbara processer. Brister i tidigare utförd forskning om liknande strukturer som grafenöverföring och dålig CNT-anpassning är lösta. En ny tillväxtmekanism undersöks också för att lägga grunden för forskning om ett nytt tillvägagångssätt för att växa Graphene- CNT hybridstrukturer i framtiden. Chemical Vapor Deposition (CVD) var metoden som användes för att odla grafen- och CNT-strukturerna. Karakteriseringen gjordes med optisk mikroskopi, Scanning electron microscopy (SEM) och Raman-spektroskopi.

storage devices in micro sizes are receiving more and more attention. One of them, on-paper Microsupercapacitors (MSCs), has become a key energy storage device because of its good mechanical flexibility and high power density. In this project, a triphase system with electrochemically exfoliated graphene and graphene quantum dots to synergistically stabilize PEDOT:PSS in ethylene glycol/water solvent was developed for scalable and reliable inkjet printing. Without any post-treatment, the printed patterns with a large thickness (up to 9 μm, about 0.4 μm per layer) attain a sheet resistance of as low as 4 Ω2−1 and high resolution at a small drop spacing of 10 μm. Thanks to these feature, the areal capacitance of the on-paper MSCs can reach >2 mF cm−2 at a high scan rate of 1000 mV s−1. The device also exhibits excellent mechanical flexibility, long cycle life (>95% capacitance retention after 10000 cycles CV test) and long service time (retain 84% capacitance after 4 months in air without any encapsulation). Moreover, we can directly print the interconnect to connect 4 devices on paper substrate in series or in parallel and thus get rid of metal current collector. / Med den snabba utvecklingen av flexibel och bärbar elektronik får energilagringsenheter i mikrostorlek allt mer uppmärksamhet. En av dem, mikrosuperkondensatorer (MSC) på papper, har blivit en viktig energilagringsenhet på grund av sin goda mekaniska flexibilitet och höga effekttäthet. I det här projektet utvecklades ett trefasigt system med elektrokemiskt exfolierad grafen och grafenkvantprickar för att synergistiskt stabilisera PEDOT:PSS i etylenglykol/vattenlösningsmedel för skalbar och tillförlitlig bläckstråleutskrift. Utan någon efterbehandling uppnår de tryckta mönstren med stor tjocklek (upp till 9 μm, ca 0,4 μmper lager) ett arkmotstånd på så lågt som 4 Ω2−1 och hög upplösning vid ett litet droppavstånd på 10 μm. Tack vare dessa egenskaper kan den ytliga kapacitansen hos MSC på papper nå >2 mF cm−2 vid en hög skanningshastighet på 1000 mV s−1. Anordningen uppvisar också utmärkt mekanisk flexibilitet, lång livslängd (>95% kapacitansbehållning efter 10000 cykler i CV-test) och lång livslängd (behåller 84% kapacitans efter 4 månader i luft utan inkapsling). Dessutom kan vi direkt skriva ut kopplingen för att ansluta fyra enheter på papperssubstratet i serie eller parallellt och på så sätt bli av med metallströmkollektorn.

Dynamic atomistic description of bio-inorganic interfaces represents a challenging problem for contemporary computational chemistry. A detailed analysis of processes occurring on the interface between biomolecule and inorganic material can help our understanding of various processes, ranging from chromatography and protein separation to protein immobilization techniques and their effect on enzyme activity or protein conformational stability. High complexity of bio- inorganic interfaces prevents detailed investigation using accurate, but computationally demanding ab initio methods. Since reliable empirical potentials are not available for these systems, the aim of this work is to develop force fields based on ab initio data as well as a general methodology for parameterization of such force fields. Our potential fitting procedure was carried out in an automated fashion based on molecular dynamics simulation. The resulting potentials were applied for investigation of inorganic material's influence on polypeptide conformations.

In last two years, the proposal to create artificial graphene in standard semiconducting 2D systems via surface patterning has emerged. This way, an alternative system would be created, allowing us to study phenomena related to Dirac-type particles in a fully carbon free system. The main idea of the concept assumes the creation of an additional potential in a quantum well by nanopatterning of the specimen surface or by using local electrodes. The additionally introduced modulation can transform the conventional (i.e. parabolic) energy dispersion into separated minibands with possible appearance of Dirac cones. In the theoretical part, we introduce four basic criteria that estimate appropriate technological parameters and the required experimental conditions. Experimentally, we study the cyclotron resonance of prepared heterostructures AlGaAs/GaAs with induced hexagonal potential via the etching lateral holes. The observed multi-mode resonance response is discussed with respect to the expected appearance of Dirac cones.

Thesis (Doktorwürde)--Friedrich-Alexander-Universität Erlangen, 1902. / Includes bibliographical references.

This thesis deals with the detection of gases. Based on the research, the theoretical part is devoted to the principles and construction of chemical gas sensors, especially the chemoresistive gas sensors, mainly with the active layer consisting of metal oxides and carbon nanotubes. In the second half of the theoretical part the carbon nanostructures, their properties and the methodology of preparation are reviewed. The experimental part deals with the type of support structure, preparation of the active layer and the method of its deposition and he principle of detection. In the results and discussion, the thesis focuses on the detailed processing of the results and the evaluation of the response ammonia, the impact of the modifications and procedures. In the end, the results obtained are compared, both with each other and with the relevant literature.