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Highly ordered cobalt oxide thin films for model catalysis
Ronovský, Michal ; Mysliveček, Josef (advisor) ; Švec, Martin (referee)
Hydrogen processing is becoming increasingly important not only in the production of electricity but also during its accumulation. One of the energy storage options are liquid organic hydrogen carriers (LOHC). The main drawback of LOHC is the need for a large amount of thermal energy to release molecular hydrogen. We can bypass this issue using heterogeneous catalysis by transferring hydrogen from LOHC to acetone and using the produced 2-propanol (IPA) in the fuel cell. This innovative strategy of getting electri- cal energy from LOHC can be potentially energetically neutral. In this work, we studied highly ordered Co3O4(111) model catalysts for IPA oxidation in the as-prepared state and enhanced with platinum (Pt) nanoparticles. Catalysts were prepared by Physical Vapour Deposition (PVD) and further investigated by means of Low Energy Electron Diffrac- tion (LEED), X-ray Photoelectron Spectroscopy (XPS), Scanning Tunneling Microscopy (STM) and Temperature Programmed Desorption (TPD). The nucleation process of Pt on the as-prepared Co3O4(111) surface was studied by depositing low amounts 0.04 and 0.13 monolayer (ML) of Pt, that create clusters as small as 2 or 3 atoms with no need for a special nucleation site. We have identified the formation of Pt-induced defects in the atomically flat cobalt oxide...
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Highly ordered cobalt oxide thin films for model catalysis
Ronovský, Michal ; Mysliveček, Josef (advisor) ; Švec, Martin (referee)
Hydrogen processing is becoming increasingly important not only in the production of electricity but also during its accumulation. One of the energy storage options are liquid organic hydrogen carriers (LOHC). The main drawback of LOHC is the need for a large amount of thermal energy to release molecular hydrogen. We can bypass this issue using heterogeneous catalysis by transferring hydrogen from LOHC to acetone and using the produced 2-propanol (IPA) in the fuel cell. This innovative strategy of getting electri- cal energy from LOHC can be potentially energetically neutral. In this work, we studied highly ordered Co3O4(111) model catalysts for IPA oxidation in the as-prepared state and enhanced with platinum (Pt) nanoparticles. Catalysts were prepared by Physical Vapour Deposition (PVD) and further investigated by means of Low Energy Electron Diffrac- tion (LEED), X-ray Photoelectron Spectroscopy (XPS), Scanning Tunneling Microscopy (STM) and Temperature Programmed Desorption (TPD). The nucleation process of Pt on the as-prepared Co3O4(111) surface was studied by depositing low amounts 0.04 and 0.13 monolayer (ML) of Pt, that create clusters as small as 2 or 3 atoms with no need for a special nucleation site. We have identified the formation of Pt-induced defects in the atomically flat cobalt oxide...
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Experimental control of Ce3+ concentration in ceria based model catalysts
Stetsovych, Vitalii ; Mysliveček, Josef (advisor) ; Lykhach, Yaroslava (referee) ; Rezek, Bohuslav (referee)
Concentration of Ce3+ is one of the most important parameters that influence the reactivity of ceria based catalyst. In this work we examine different experimental approaches for controlling Ce3+ concentration in cerium oxide model catalyst systems such as: i) influencing the stoichiometry of ceria, ii) introducing high valence doping agent, and iii) growing ultra thin ceria films with a strong metal substrate interaction. Structure, morphology and chemical state of prepared reduced ceria based systems were examined by means of surface science techniques: scanning tunneling microscopy, low-energy electron diffraction and X-ray photoelectron spectroscopy. In the present work an original method of ceria film reduction was introduced that allows stepwise control on stoichiometry and degree of film reduction (i). Further we introduce preparation procedures for well-ordered tungsten doped ceria model system (ii) and for the high quality 2D ultrathin ceria system on Cu (1 1 1) (iii). Preparation methods and model systems introduced in this work incorporate different physicochemical principles of Ce3+ induction and provide a variety of model systems useful for examining different effects that diversely prepared Ce3+ ions have on the activity of the catalyst.
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