0000000000369553
AUTHOR
Krišjānis ŠMits
DBpedia sistēmas izpēte un latviskās versijas izveide
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Aqueous synthesis of Z-scheme photocatalyst powders and thin-film photoanodes from earth abundant elements
Riga Technical University supported the preparation of this manuscript from the Scientific Research Project Competition for Young Researchers No. ZP 2017/8
Luminescence of Eu ion in alumina prepared by plasma electrolytic oxidation
Abstract Eu ion luminescence in aluminium oxide nanocrystals and layers prepared by plasma electrolytic oxidation (PEO) are investigated in this study. The Eu ion in PEO coatings has intense luminescence allowing such material to be used for preparation of various phosphor materials. In this study, Eu ion doped coatings were prepared with two methods: anodization and pulsed bipolar plasma electrolytic oxidation. Also, for comparative studies, alumina nanocrystals with the same amount of Eu ions were prepared using Sol Gel and molten salts methods. Obtained Eu-doped coatings were studied using luminescence methods. Typical Eu ion luminescence bands were observed, however intensity and spectr…
CO2 turned into a nitrogen doped carbon catalyst for fuel cells and metal–air battery applications
Heteroatom doped metal-free catalysts are one of the most promising replacements for platinum for the alkaline oxygen reduction reaction (ORR). Due to the lack of metal atoms, they are extremely stable and environmentally friendly. However, production of carbon nanomaterials can have a very high CO2 footprint. In this study, we present ORR catalysts made directly from CO2via molten salt CO2 electrolysis. The deposited carbon powder is doped with nitrogen using pyrolysis in the presence of dicyandiamide. The effect of molten carbonate electrolyte composition towards the final ORR activity in 0.1 M KOH is studied. A thorough physico-chemical study of the starting carbons and N-doped catalysts…
Luminescence of Er/Yb and Tm/Yb doped FAp nanoparticles and ceramics
The nanoparticles of hydroxiapatite and fluorapatite doped with Er/Yb and Tm/Yb were synthesized and characterized by FTIR, XRD, SEM and TEM methods. The results of up-conversion luminescence studies were presented for the samples as prepared, annealed at 500°C and at 900-1000 °C. At annealing above 800°C the ceramic state was formed. It is shown that fluorapatite host is more appropriate than hydroxiapatite host for rare ions luminescence and up-conversion processes. The post preparing annealing of nanarticles significantly enhanced the luminescence intensity. The Tm/Yb doped fluorapatite shows intense up-conversion luminescence in 790-800 nm spectral region and is potentially useful for b…
Rapid Catalytic Water Disinfection from Earth Abundant Ca 2 Fe 2 O 5 Brownmillerite
Water disinfection is a crucial challenge for humanity. Approaches that are effective, cheap, environmentally friendly, and do not promote gene exchange between bacteria are urgently required. Strongly oxidizing radicals are highly promising to achieve this as they lead to bacterial activation at high efficiencies. However, sources to consistently generate these radicals are limited to high energy UV/H2O2 treatments requiring a large energy input. Here the use of abundant, cheap, brownmillerite (Ca2Fe2O5) is demonstrated as an efficient radical generation material under dark conditions, showing a seven order of magnitude decrease in bacterial concentration over 10 min. This decrease is attr…
Permanent photodoping of plasmonic gallium-ZnO nanocrystals
This work was supported by the Latvian Council of Science in the framework of FLPP (Plasmonic oxide quantum dots for energy saving smart windows, lzp-2018/1-0187). Tanel Käämbre acknowledges financial support for the XPS instrumentation maintenance from the Estonian Centre of Excellence in Research project “Advanced materials and high- technology devices for sustainable energetics, sensorics and nanoelectronics” (TK141).
Liquid-assisted grinding/compression: a facile mechanosynthetic route for the production of high-performing Co–N–C electrocatalyst materials
This research was supported by the Estonian Research Council grant PSG250; and by the EU through the European Regional Development Fund (TK141, “Advanced materials and high-technology devices for energy recuperation systems” and TK143, “Molecular Cell Engineering”).
Pasākumu organizēšanas tīmekļa vietne
Kvalifikācijas darbā izstrādāta un aprakstīta pasākumu organizēšanas vietne. Vietnē lietotājs var izveidot pasākuma aprakstu, ar mērķi informēt pasākuma dalībniekus, vai piesaistītu potenciālos dalībniekus. Pastāv divi pasākuma veidi – publisks, kur jebkuram reģistrētam lietotājam ir tiesības kļūt par organizatoru, tādējādi iegūstot tiesības mainīt pasākuma informāciju, un privāts pasākums, kurā lietotāji nevar iegūt tiesības mainīt pasākuma informāciju. Lietotājs var reģistrēties izmantojot vietnes reģistrāciju, vai arī pieslēgties izmantojot facebook vai draugiem.lv sociālo tīklu profilu. Nereģistrētam lietotājam ir tiesības tikai apskatīt pasākuma informāciju. Vietnes operatoriem ir piee…
The role of Nb in intensity increase of Er ion upconversion luminescence in zirconia
It is found that Nb co-doping increases the luminescence and upconversion luminescence intensity in rare earth doped zirconia. Er and Yb-doped nanocrystalline samples with or without Nb co-doping were prepared by sol-gel method and thermally annealed to check for the impact of phase transition on luminescence properties. Phase composition and grain sizes were examined by X-ray diffraction; the morphology was checked by scanning- and high-resolution transmission electron microscopes. Both steady-state and time-resolved luminescence were studied. Comparison of samples with different oxygen vacancy concentrations and different Nb concentrations confirmed the known assumption that oxygen vacanc…
Photocatalytic Activity of TiO2 Coatings Obtained at Room Temperature on a Polymethyl Methacrylate Substrate
Titanium dioxide (TiO2) coatings have a wide range of applications. Anatase exhibits hydrophilic, antimicrobial, and photocatalytic properties for the degradation of organic pollutants or water splitting. The main challenge is to obtain durable anatase nanoparticle coatings on plastic substrates by using straightforward approaches. In the present study, we revealed the preparation of a transparent TiO2 coating on polymethylmethacrylate (PMMA), widely used for organic optical fibres as well as other polymer substrates such as polypropylene (PP), polystyrene (PS), and polycarbonate (PC). The films were spin-coated at room temperature without annealing; therefore, our approach can be used for …
Cirkonija dioksīda nanokristālu luminiscence
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