Organic Electrolytes for Thermoelectric Devices and CNT Electrode functionalization by Nitrogen-doping
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In this thesis a thermoelectric cell is developed. Aligned Carbon Nanotubesand aligned Nitrogen-doped Carbon Nanotubes are used as electrode materials.Ferri/Ferrocyanide and Tetrabutylammonium Nitrate (TBAN) electrolyteshave been tested for thermoelectric performance, with the two different electrodematerials. It was found that Nitrogen doping of CNT's enhances reaction kineticsof the Ferro/Ferricyanide redox reaction. It is suggested that there will be an ideallevel of doping, where the electron transfer rate is maximized.TBAN showed the highest open circuit voltage, but it was discovered thatTBAN in dodecanol was unsuitable as an electrolyte for thermocells due to lowconductivity and unstable current. The current decreased to less than 1 A insome seconds.The highest thermoelectric eciency obtained was for a symmetric NCNT elec-trode conguration, with the Ferrocyanide redox couple. The eciency was 0.007% of the Carnot efficiency, which is less than state-of-the art electrolyte thermo-cells. The lower eciecy was due to non-optimized electrodes and current leakagesin the test cell.Dense, uniform and aligned CNT's were grown on Aluminum foil but using apre-deposited 2 nm layer of iron catalyst. Ammonia annealing was required beforeCVD. The treatment with ammonia lead to longer catalyst lifetimes and betteralignment. Lengths up to 110 m was obtained, 15 nm in diameter.Growth of aligned N-doped CNT's on Aluminum was done using a floating catalyst method. Up to 1.5 % incorporation of Nitrogen was achieved.