|
|
Preparation and characterization of nanomaterials for electrochemical energy storage
Bouša, Milan ; Kavan, Ladislav (advisor) ; Fejfar, Antonín (referee) ; Velický, Matěj (referee)
Graphene research is nowadays one of the worldwide most prominent fields of interest in material science due to many extraordinary properties of graphene and related materials. However, the different techniques of synthesis and subsequent handling and/or treatment have a substantial impact on the properties of the graphene and thus a lot of efforts have been focused on developing of the advanced methods for graphene preparation and characterization. Graphene can be easily produced by oxidation and consequent exfoliation of the bulk graphite; however, resulting graphene oxide needs to be reduced back to graphene-like structure due to partial restoration of sp2 network. Herein, a detailed study of the structural evolution of the graphene oxide during electrochemical treatment has been performed using X-ray photoelectron, Raman and infrared spectroscopies and the results were compared with non-oxidized graphene nano-platelets. Additionally, graphene oxide in composite with LiFePO4 olivine material, which is electrochemically almost inactive in a freshly made state, has been tested by repeated electrochemical cycling. Using various electrochemical methods, the progressive electrochemical activity enhancement has been observed and spontaneous graphene reduction was identified as responsible for this...
|
|
|
Spectroelectrochemical cell with CD-trode
Hladík, Martin ; Nesměrák, Karel (advisor) ; Rychlovský, Petr (referee)
This bachelor thesis was aimed on the optimisation of preparation of gold electrodes (CDtrodes) from commercially available DVDs by treatment of concentrated nitric acid. The duration of the treatment was set on 20 minutes, based on study of voltammetric responses of fabricated CDtrodes. The CDtrodes were employed in spectroelectrochemical cells in two arrangements (i) with beam perpendicular to the area of electrode, and (ii) with beam collinear to the area of electrode. The formation and extinction of phenothiazine radicals during cyclic voltammetry were followed spectrophotometrically. Key words: spectroelectrochemistry, CDtrode, phenothiazine
|
|
| |
|
|
FOX-7 - Study of Reduction Products of Spectroelectrochemical Methods
Šimková, Ludmila ; Dmitrieva, E. ; Klíma, Jiří ; Dunsch, L. ; Ludvík, Jiří
A new energetic material 2,2-dinitroethene-1,1-diamine (FOX-7) is recently broadly tested because of its high performance and very low sensitivity. On the other hand, its electrochemical and redox properties have not been studied yet. Our results show that FOX-7 is reduced in aprotic solvents only by two one-electron steps up to -2.9 V. The color changes during reduction of FOX-7 and reversibility of the redox process indicate the presence of radical intermediates. Therefore in situ UV-vis-NIR and ESR spectroelectrochemical investigations were performed. The products after exhaustive electrolyses were separated by HPLC and are identified by mass spectrometry. The possible formation of gaseous products was followed online EC-GC.
|
guest ::
