Suchergebnisse

Growing need for cleaner environment and energy production has brought about a hunt for perspective materials. One of such perspective materials is titanium dioxide (TiO2, titania) due to its chemical stability and photocatalytic properties. Titania can be synthesized through many methods but anodization process is one of the prevailing methods to produce high active surface nanostructured titania. Various anodization electrolytes produce different polymorphs of TiO2. Uniform phase distribution on the surface is crucial for higher photocatalytic activity. In this research, the influence of two electrolytes on polymorph phase distribution of TiO2 was investigated. Phase distribution correlation with optical band gap, charge density and photocurrent values were tested. Successful Raman investigation of anodized titania revealed uniform, single and multi-phase, as well as nonuniform phase distributions produced respectively in PO43‒ and SO42‒ ions containing electrolytes. Uniform single phase titania shows highest photocurrent (PCR) and charge density values compared to phase composition and nonuniform phase distributions. We have shown Raman microprobe analysis as indispensable method for wholesome sample characteristics. ; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union's Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART²

The authors gratefully acknowledge financial support from the Latvian Council of Science, Project LZP FLPP No. LZP-2018/1 0194, and the Institute of Solid State Physics, University of Latvia that as the Center of Excellence has received funding from the European Union's Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2026-2017-TeamingPhase2 under Grant Agreement No. 739508, Project CAMART2. ; Graphene was discovered in the early 21st century, but has already proven itself in many applications – energy, medicine, electronics, food and sports, and more. Functionalization of nanostructured carbon materials with both non-metallic and metallic atoms is possible in various ways, imparting enhanced or new properties to the starting material, even catalytic activity. A method of electrochemical exfoliation was used to obtain the graphene sheets and simultaneously functionalize them with nitrogen. To ensure N-doping the process is done in a NaN3 electrolyte solution which provides less quantity of oxygen groups that tend to block defect sites on the graphene, compared with such solvents as NaNO2. Two graphite electrodes are inserted into the electrolyte and a pulse power of 0–10V is applied. The solution containing the obtained material is filtered through a 0.1 µm filter and dried. The material is characterized using SEM, XRD and XPS. In the XPS characterization graphene oxide is used as a reference material. ; Latvian Council of Science, Project LZP FLPP No. LZP-2018/1 0194; the Institute of Solid State Physics, University of Latvia that as the Center of Excellence has received funding from the European Union's Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2026-2017-TeamingPhase2 under Grant Agreement No. 739508, Project CAMART2.

The research has been funded by the Ministry of Economics of the Republic of Latvia, project "Trends, Challenges and Solutions of Latvian Gas Infrastructure Development (LAGAS)", project No. VPP EM-INFRA-2018/1-0003. ; As EU is steadily moving in the direction of emission reduction, each country must develop plans to decarbonise the transport and energy sectors. In Latvia, transport sector is one of the biggest emission sources. The heating applications come next. Both require carbon containing fuels and a transfer to carbon neutral fuel is necessary; therefore, hydrogen may be the answer to achieve the overall EU targets. As Latvia has renewable energy sources, some production, storage and use of hydrogen are possible. Currently clear guidelines for Latvia have been investigated. The existing natural gas network may be used for two tasks: large-scale hydrogen transportation and decarbonisation of natural gas network. To open the natural gas networks for hydrogen, the first evaluations are made and a possible scenario for hydrogen implementation in network supplying consumers in the household sector is analysed to evaluate decarbonisation with an overarching goal of carbon neutrality. ---//---This work is licensed under a CC BY 4.0 license. ; Ministry of Economics of the Republic of Latvia project No. VPP EM-INFRA-2018/1-0003; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union's Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART².

The research was funded by the Latvian Council of Science project "Nanostructured Nitrogenated Carbon Materials as Promoters in Energy Harvesting and Storage Technologies", project No LZP-2018/1-0194, "New biomass origin materials hybrid carbon composites for energy storage" project No LZP-2020/2-0019 and postdoc project "Nitrogen and phosphorus-containing biomass based activated carbons for fuel cells and supercapacitors" project No 1.1.1.2/VIAA/4/20/596. ; Fuel cells, batteries and supercapacitors are critical to meet the rising global demand for clean, sustainable energy. Biomass-derived activated carbon can be obtained with tailored properties to fulfil the extensive need for low-cost, high-performance, catalyst and electrode materials. To investigate the possibility of nanoporous nitrogen-doped carbon materials as catalysts in fuel cells and electrodes in lithium-ion batteries, biomass precursors were thermochemically activated with NaOH at 800 °C, nitrogen was introduced using dicyandiamide and doping was performed at 800 °C. The chemical composition, porous structure, texture and electrochemical properties of the obtained materials change depending on the biomass precursor used. It has been found that the most promising precursor of the obtained materials is wood char, both as an oxygen reduction catalyst in fuel cells, which shows better properties than the commercial 20% Pt/C catalyst, and as an anode material in Li-ion batteries. However, catalysts based on black liquor and hybrid material have comparable properties with commercial 20% Pt/C catalyst and can be considered as a cheaper alternative. © 2021 by the authors. Licensee MDPI, Basel, Switzerland. ; Latvian Council of Science LZP-2018/1-0194, LZP-2020/2-0019; postdoc project 1.1.1.2/VIAA/4/20/596; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union's Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2.

Energy harvesting with lowest environmental impact is one of key elements for cleaner future. Photocatalytic as well as electrocatalytic CO2 reformation processes are considered as prominent methods. Thus, extensive research of CO2 reformation is being done to find the right materials that holds crucial qualities. For photocatalysis that includes pronounced separation of light-generated opposite sign charge carriers, sensitivity to visible light, high quantum yield. In electrocatalysis high CO2 adsorption, chemical stability, multielectron reaction catalysts are necessary. Additionally, materials participating in the reaction process must be provided with charge carriers at proper reduction and oxidation potentials. To meet the set goal of lowering environmental impact and lower CO2 amounts exhausted into the atmosphere by human activities, it is necessary to find right technology for capturing, storing, and reusing carbon dioxide. Various technologies and materials in different levels of readiness are available and under development, such as CuO loaded TiO2 nanotubes for photocatalytic reformation or electrocatalytic reduction on copper. Not only the proof of concept is necessary but estimation and more importantly determination of the efficiency of both electro and photo catalytic reformation of CO2. In this work review of reactions and efficiency of both processes based on existing established technological methods is done. ; Horizon 2020 Research and Innovation Program 768789; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union's Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART²