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Title Laser induced periodics surface structures on nickel electrodes for hydrogen production through alkaline electrolysis
Author Τσανάκας, Μιχαήλ-Δωρόθεος
Thesis advisor Λουκάκος, Παναγιώτης
Reviewer Φωτάκης, Κωνσταντίνος
Μουσταϊζής, Σταύρος
Abstract The following thesis was conducted in the Femtosecond Laser Spectroscopy in Solid State (FLASSS) laboratory of the Institute of Electronic Structure and Laser (IESL) of Foundation for Research and Technology– Hellas (FORTH) in collaboration with the Matter Structure and Laser Physics Laboratory of the Technical University of Crete. The purpose of this thesis is the fabrication of nanostructures on Nickel surfaces through irradiation by high fluence, ultrashort laser pulses, and the use of the nanostructured sheets as electrodes in alkaline electrolysis for Hydrogen production. Scanning Electron Microscope was employed in order to assess the morphological characteristics of the obtained surfaces. We found that periodic surface nanostructures are formed by the laser irradiation. We performed a study of the different parameters that define the formation of the nanostructures, such as the polarization of the laser beam, the intensity and the scanning speed of the sample, or equivalently, the number of incident pulses per spot. The results showed that the periodicity is not affected by the scanning direction and also that there is no relation between the periodicity and the number of pulses irradiating a spot. The periodicity of the nanostructures is thus defined by the intrinsic properties of the material and the wavelength of the incident laser field. The fabricated nanostructured electrodes were used in an electrolysis chamber for the evaluation of Hydrogen production. We found a significant enhancement of Hydrogen production when nanostructured electrodes are used. The results provide evidence that the electrodes irradiated with a larger number of pulses per spot are more beneficial to Hydrogen production. An enhancement factor of 3.7 with respect to the flat i.e. unstructured electrodes was found which is a remarkable improvement to the state of the art. The results are very encouraging for continuing studies in this direction employing different surface nanostructures, laser parameters and combinations of electrode materials.
Language English
Issue date 2021-03-24
Collection   School/Department--School of Sciences and Engineering--Department of Physics--Graduate theses
  Type of Work--Graduate theses
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