Porous, conductive metallic nanostructures are required in several fields, such as energy conversion, low-cost sensors etc. This thesis reports on the development of an electrocatalytically active and conductive membrane for use in Polymer Electrolyte Membrane Fuel Cells (PEMFCs) and fabrication of low-cost substrates for Surface Enhanced Raman Spectroscopy (SERS). One of the main challenges facing large-scale deployment of PEMFCs currently is to fabricate a catalyst layer that minimizes platinum loading, maximizes eletrocatalytically active area, and maximizes tolerance to CO in the feed stream. Modeling the kinetics of platinum catalyzed half cell reactions occurring in a PEMFC using the kinetic theory of gases and incorporating appropriate sticking coefficients provides a revealing insight that there is scope for an order of magnitude increase in maximum current density achievable from PEMFCs. To accomplish this, losses due to concentration polarization in gas diffusion layers, which occur at high current densities, need to be eliminated. A novel catalyst design, based on a porous metallic nanostructure, which aims to overcome the limitations of concentration polarization as well as minimize the amount of platinum loading in PEMFCs is proposed. Fabrication steps involving controlled in-plane fusion of self-assembled arrays of core-shell gold-platinum nanoparticles (Au@Pt) is envisioned. The key steps involved being the development of a facile synthesis route to form Au@Pt nanoparticles with tunable platinum shell thicknesses in the 5 nm size range, the formation of large-scale 2D arrays of Au@Pt nanoparticles using guided self-assembly, and optimization of an RF plasma process to promote in-plane fusion of the nanoparticles to form porous, electrocatalytically active and electrically conductive membranes. This thesis consists of seven chapters. The first chapter provides an introduction into the topic of PEMFCs, some perspective on the current status of research and development of PEMFCs, and an outline of the thesis. The second chapter provides an overview on the methods used, characterization techniques employed and protocols followed for sample preparation. The third chapter describes the modelling of a PEMFC using the Kinetic theory of gases to arrive at an estimate of the maximum feasible current density, based on the kinetics of the electrocatalytic reactions. The fourth chapter presents the development of a simple protocol for synthesizing Au@Pt nanoparticles with control over platinum shell thicknesses from the sub monolayer coverage onwards. The results of spectroscopic and microscopic characterization establish the uniformity of coating and the absence of secondary nucleation. Chapter five describes the formation of a nanoporous, electrocatalytically active membrane by self-assembly to form bilayers of 2D arrays of Au@Pt nanoparticles and subsequent fusion using an RF plasma based process. The evolution of the electrocatalytic activity and electrical conductivity as a function of the duration of RF plasma treatment is monitored for Au@Pt nanoparticles with various extent of platinum coating. Spectroscopic, microscopic, electrical and cyclic voltammetry characterization of the samples at various stages were used to understand the structural evolution with RF plasma treatment duration and discussed. Next durability studies were carried out on the nanoporous, Au@Pt bilayer nanoparticle array with an optimum composition of Pt/Au atomic ratio of 0.88 treated to 16 minutes of argon plasma exposure. After this the novel catalyst membrane design of PEM fuel cell is revisited. Two different techniques are proposed so that the thin, nanoporous, metallic catalyst membrane achieves horizontal electronic resistance equivalent to that of the conventional gas diffusion layer with catalyst layer. The first technique proposes the introduction of gold coated polymeric mesh in between the thin, nanoporous, metallic catalyst membrane and bipolar plate and discusses the advantages. Later the gold coated polymeric mesh is introduced in a conventional membrane electrode assembly and efficiency of the polarization curves probed with and without the introduction of gold coated polymeric mesh. The second technique describes the results of fabrication of a nanoporous metallic membrane using multiple layers of 2D Au@Pt nanoparticle arrays at an optimum composition of Pt/Au atomic ratio of 0.88 to reduce the horizontal electronic resistance. Preliminary studies on the permeability of water through such membranes supported on a porous polycarbonate filter membrane are also presented. In chapter six, a simple reactive inkjet printing process for fabricating SERS active silver nanostructures on paper is presented. The process adapts a simple room temperature protocol, using tannic acid as the reducing agent, developed earlier in our group to fabricate porous silver nanostructures on paper using a commercial office inkjet printer. The results of SERS characterization, spectroscopic and microscopic characterizations of the samples and the comparison of the substrate’s long-term performance with respect to a substrate fabricated using sodium borohydride as the reducing agent is discussed. Preliminary findings on attempts to fabricate a conductive silver network using RF plasma induced fusion area also presented. Chapter seven provides a summary of the results, draws conclusions and a perspective on work required to accomplish the goals of incorporating the porous metallic nanostructures into PEMFCs.

The thesis deals with the principle functions of low-temperature fuel cells with proton exchange membrane (PEMFC), photovoltaic sources (PVPP) and wind energy sources (WPP), along with solving their detailed mathematical expressions. In this work, the individual sources and their simulated models are analyzed in depth. The actual simulation is preceded by familiarization with important historical milestones in the development of fuel cells. Furthermore there is a basic classification of fuel cells and the characteristics of the cells used in the energy sectors. The text also provides information on projects that address the implementation of PEMFC as a primary or supplementary source of energy. Along with outlining the options for PEMFC as a perspective hydrogen technologies in the near future, the basic methods of hydrogen production and storage options are presented for the complexity. The work is exclusively focused on improving PEMFC mathematical models that under the hybrid system cooperate with renewable energy sources (RES). Part of the theses contains a short review of run or modeled concepts of hybrid systems in the energy sector. Using these models the main deficiencies of the models or of the whole PEMFC system can be identify. Specifications of the deficiencies lead to the creation of a new advanced dynamic PEMFC model that allows an analysis of the development of electrical and non-electrical quantities using long term tests. Furthermore, the thesis presents results of the experiments of thermal and dynamic behavior PEMFC, which were obtained from the additionally extended model with a reformer and the DC/DC converter. In this text there is a model of a photovoltaic module created, which is based on the nominal values parameterization. The model is subjected to basic experiments in which measured hydrometeorological data are used. If the hybrid system utilizes renewable energy sources, it is good to know the evolution of atmospheric conditions in the installation of these resources. Specifically for PVPP, publicly available databases containing information about solar radiation levels can be used for the selected location. Public databases are often used for initial design and manufacturing options for PVPP. An evaluation of the relevancy of public databases is performed based on a long-term observation of real measured data. Furthermore, these data are used for experiments on the photovoltaic module. Partially the text addresses the issue of the wind energy sources, however, it is simulated only on a simplified model of WPP. Created models of subsystems can be generally implemented as partial inputs hybrid systems in the future work. The thesis was developed at Centre for Research and Utilization of Renewable Energy (CVVOZE) with the financial support of the National Programme for Sustainability and the Ministry of Education, Youth and Sports of the Czech Republic under the project no. LO1210 - Energy for Sustainable Development and the project no. FEKT-S-14-2520 - New Technologies for Sustainable Development of Electrical Power Systems. The thesis was also generated under the project no. TA03020523 - Dynamic model of distribution network with the financial support of Technology Agency of the Czech Republic.

This thesis explores what Karlstad Airport needs to go 100% green. Photovoltaics are assumed to be installed at the facility and a Hydrogen Energy Storage System and Battery Energy Storage System will be evaluated to reduce peaks during charging of the planes. Different power peak limits are explored as well as different sized Energy Storage Systems and later evaluated economically. A method to find the cheapest possible system is created with some assumptions and is then used to evaluate throughout the whole dataset. In the end any of the different sized Energy Storage Systems reduces the profitability when considering each systems expected lifecycle.

Improving the efficiency and performance of vehicle propulsion systems has always been desirable, and with increasing environmental awareness this has become increasingly topical. A particularly strong focus today is at fossil-free alternatives, and there is a strong trend for electrification. Hybrid powertrains of different types can bring benefits in certain aspects, and there is a lot of research and development involved in the making of a new powertrain. In this thesis, a complete powertrain for a fuel cell hybrid electric vehicle is modeled, with the intention of contributing to this trend. The model can be used to investigate design choices and their impact on energy consumption. A component-based library is developed, with the purpose of being easy to implement for different configurations. The results show that it is possible to assemble and simulate a complete hybrid drivetrain, using the modeled components, while not being very computationally heavy. The developed models correspond well with reality while being modular and easy to implement.

In this research, a proton exchange membrane fuel cell (PEMFC) sensor was investigated for specific detection of volatile organic compounds (VOCs) for point-of-care (POC) diagnosis of the physiological conditions of humans. A PEMFC is an electrochemical transducer that converts chemical energy into electrical energy. A Redox reaction takes place at its electrodes whereas the volatile biomolecules (e.g. ethanol) are oxidized at the anode and ambient oxygen is reduced at the cathode. The compounds which were the focus of this investigation were ethanol (C2H5OH) and isoflurane (C3H2ClF5O), but theoretically, the sensor is not limited to only those VOCs given proper calibration. Detection in biosensing, which needs to be carried out in a controlled system, becomes complex in a multivariate environment. Major limitations of all types of biosensors would include poor selectivity, drifting, overlapping, and degradation of signals. Specific detection of VOCs in multi-dimensional environments is also a challenge in fuel cell sensing. Humidity, temperature, and the presence of other analytes interfere with the functionality of the fuel cell and provide false readings. Hence, accurate and precise quantification of VOC(s) and calibration are the major challenges when using PEMFC biosensor. To resolve this problem, a statistical model was derived for the calibration of PEMFC employing multivariate analysis, such as the “Principal Component Regression (PCR)” method for the sensing of VOC(s). PCR can correlate larger data sets and provides an accurate fitting between a known and an unknown data set. PCR improves calibration for multivariate conditions as compared to the overlapping signals obtained when using linear (univariate) regression models. Results show that this biosensor investigated has a 75% accuracy improvement over the commercial alcohol breathalyzer used in this study when detecting ethanol. When detecting isoflurane, this sensor has an average deviation in the steady-state response of ~14.29% from the gold-standard infrared spectroscopy system used in hospital operating theaters. The significance of this research lies in its versatility in dealing with the existing challenge of the accuracy and precision of the calibration of the PEMFC sensor. Also, this research may improve the diagnosis of several diseases through the detection of concerned biomarkers.

In recent years, Polymer Electrolyte Membrane Fuel Cells (PEMFC) have attracted much attention due to their potential as a clean power source for many applications, including automotive, portable and stationary devices. This resulted in a tremendous technological progress, such as the development of new membranes and electro-catalysts or the improvement of electrode structures. However, in order to compete within the most attractive markets, the PEMFC technologies did not reach all the required characteristics yet, in particular in terms of cost and durability.Because of the strong coupling between different physicochemical phenomena, the interpretation of experimental observations is difficult, and analysis through modeling becomes crucial to elucidate the degradation and failure mechanisms, andto help improving both PEMFC electrochemical performance and durability.The development of a theoretical tool is essential for industrials and the scientific community to evaluate the PEMFC degradation and to predict itsperformance and durability in function of the materials properties and in a diversity of operating conditions. This manuscript summarizes my scientific research efforts in this exciting topic during the last 9 years in France, including my invention of the MEMEPhys multiscale simulation package,developed on the basis of my childhood passion for the New Technologies for Energyin Argentina. My perspectives of adapting this approach to other electrochemical systems such as water electrolyzers and batteries are also discussed.