|
|
Preparation and characterization of nanomaterials for electrochemical energy storage
Bouša, Milan
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 study of porphyrin derivatives in non-aqueous solvents
Povišer, Martin ; Dian, Juraj (advisor) ; Pšenčík, Jakub (referee)
Porphyrins and their derivatives constitute an important group of com- pounds taking part in vital biological processes such as transport of oxygen in blood and in photosynthesis. Electrochemical experiments such as cyclic volta- mmetry allow to examine the energetic balance of oxidation and reduction pro- cesses of particles under study. In spectroelectrochemical studies, the experiment is extended with optical characterization of the arising oxidized or reduced spe- cies. These are means to study of electronic structure of species and available electron transitions. Such studies are especially interesting in case of porphyrins due to possible elucidation of electron transfer in photosynthetic chains. This work presents: (a) an elementary theoretical treatment of electrode reactions fun- damental for electrochemical experiments, (b) description of the experimental realization of spectroelectrochemical study of porphyrins and derivatives in non- aqueous solvents, and (c) results of original spectroelectrochemical measurements on protoporphyrin IX in medium dimethylformamide. 1
|
|
|
Preparation and characterization of nanomaterials for electrochemical energy storage
Bouša, Milan
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...
|
|
|
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
|
guest ::
