Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 107 for “"overpotential"”.
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Reaction Condition Dependence of Different Overpotential Components in Electrochemical Hydrogen Catalysis
… This manifests as an applied or measured overpotential. However, there are many ways to generate non-equilibrium conditions, and correspondingly overpotential can arise from multiple different sources. Thus, the applied overpotential in an electrocatalytic system is always the aggregate of …
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Amine promotion of hydrogen evolution reaction suppression and CO2 conversion for artificial photosynthesis
… used as the proton source [4, 5]. However, the overpotential for electrolysis of water is low, whereas the overpotential of electrochemical conversion of CO2 is too high. Increasing the overpotential of water decomposition and lowering the overpotential of CO2 reduction is considered one of the …
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Development of a semi–empirical reaction kinetic model for PEM fuel cells
… (platinum and ruthenium). Furthermore 75% of the overpotential losses at the cathode are due to the activation of the oxygen reduction reaction (ORR). To reduce the platinum content requirements and understand the cause of the large overpotential of the ORR, a fundamental understanding of the …
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Engineering heme-copper and multi-copper oxidases for efficient oxygen reduction catalysis
… the actual efficiency is limited by the large overpotential (500-600 mV) of the oxygen reduction reaction (ORR), which demands a potent ORR catalyst to decrease the overpotential. Towards this goal, my thesis focuses on mimicking the heme-copper oxidase and engineering a multi-copper oxidase …
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Electrocatalytic dioxygen reduction with copper complexes
… preventing fuel cell proliferation is the high overpotentials for the ORR, the cathode reaction. Cathodes are typically constructed with Pt based catalysts, which exhibit ~300 mV of overpotential, leading to high loading of Pt and therefore large costs for the fuel cell stack. Using Nature as an …
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Investigation Of New Ligand Architechtures Towards Proton And Water Reduction Catalysis By Cobalt Complexes
… acceptor oxime in order to reduce the overpotential of hydrogen generation in organic solvents. We altered the substitution, axial ligands and axial ligand substitutions to vary electronic and catalytic properties for such tetra- or pentadentate ligand systems. Knowledge of the nature …
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Electrochemically driven phase transformation in energy storage compounds
… to undercooling and superheating. So far, overpotential effects on phase stability and transformation mechanisms have not been studied in detail. Here we use synchrotron X-ray diffraction performed in-situ during potentiostatic and galvanostatic cycling, combined with phase-field modeling, …
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Waste to an Asset, H2S to Hydrogen: A DFT Study
… catalyst for H2SOR with 0.49 V calculated overpotential. We also investigated the H2SOR activity of pristine and doped metal sulfides. We show that even doping metal sulfides reduces the overpotential needed to drive the H2SOR and facilitates hydrogen production. This research paves the way …
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Electrochemical engineering considerations for gas evolution in molten sulfide electrolytes
… conditions under which one or more sources of overpotential were negligible to facilitate analysis of the total overpotential observed at the expense of maintaining operating conditions of industrial relevance. This work represents a preliminary effort to understand the fundamental material …
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Electrochemically-induced phase transition in olivine type cathode materials
… The effects of operating conditions, especially overpotential and temperature, on phase behavior and battery performance are also investigated. Using olivine-type phosphates (i.e. phospho-olivines) with varying composition and particle size as model system, strain accommodation mechanism within …
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Mathematical Simulation of Direct Glucose Fuel Cell
… the performance of DGFC. Also, the anodic overpotential is large compared to cathodic overpotential due to complex kinetics of the glucose electrooxidation. </p>
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High-Performance Low-Cost Catalysts for Water Electrolysis: A Computational and Experimental Study
… (OER), which has slow kinetics and a high overpotential, and this issue remains unresolved. This thesis employs density functional theory (DFT) to rationally design and develop low-cost, highly active, and durable TMO catalysts prepared by plasma-enhanced atomic layer deposition (PE-ALD) …
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Mechanism of SPS acceleration in a PEG containing copper plating bath
… polyethylene glycol (PEG), under constant overpotential and measurement of the resulting current increase. The electrochemical cleavage of SPS to form MPS was also studied. SPS was placed in an acid solution in the absence of cupric ions and an overpotential was applied to split the …
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Theoretical and Experimental Investigations on Microelectrodeposition Process
… surface by applying an electric voltage, called overpotential. Different electrochemical practices were presented in the literature to obtain kinetic parameters of an electrochemical reaction but most of these practices are hard to implement for the reactions occur on a microelectrode. Toward …
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In Situ Studies of Corrosion and Electrodeposition Using Atomic Force Microscopy
… was crystallographic in 0.5 M H$\sb2$SO$\sb4$ at overpotentials up to 100 mV; addition of BTA provided corrosion inhibition up to 300 mV overpotential, where pitting occurred. Surface preparation of pure aluminum was not reproducible, and the differences altered the corrosion behavior in NaCl …
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Nanoscale heterojunctions of transition metal oxide and silicon for high-efficiency oxygen evolution reaction
… the active TiO₂ surface, thus changing the OER overpotential. This thesis examines mainly four aspects of the heterojunctions of anatase TiO₂(001) and Si: (i) the thermodynamic stability of different local stoichiometry at the TiO₂/Si interface, (ii) the electronic structures induced by the …
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Iron-oxide catalyzed silicon photoanode for water splitting
… a large built-in potential to lower the required overpotential. Additional improvement was made by adopting silicon microfabrication techniques to maximize light harvesting and minimize potential losses in silicon layer. By vertical wires and ohmic contact formation, the onset potentials were …
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Electrochemical Carbon Dioxide Reduction for Renewable Carbonaceous Fuels and Chemicals
… fuels. Unfortunately, it is hard to achieve low overpotential, high selectivity, and activity simultaneously of ECO2RR. Developing efficient electrocatalysts is the most promising strategy to enhance electrocatalytic activity in CO2 reduction. Herein, we designed novel Bi-Cu2S heterostructures by …
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ELECTRODE AND MEMBRANE MODIFICATION OF DIFFERENT REDOX FLOW BATTERIES
… systems suffer from low reaction rate and high overpotential caused by the low kinetics of 3D current collector as well as the membrane crossover issue. In this thesis, methods of improving electrode interfacial properties and the separator properties were introduced and were applied to both …
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