Raman spectral identification of phase distribution in anodic titanium dioxide coating

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 CAMART

Synthesis and studying of reduced few-layered graphene coatings in gas sensor applications

In this work reduced few-layered graphene (rFLG) nanoparticles were synthesized using electrochemical pulse exfoliation method from waste graphite crucibles. The regular change in voltage polarity in the synthesis process ensures both the separation of graphite in layers and the reduction of graphene oxide. A method for synthesizing free-standing rFLG and nitrocellulose (NC) composite film has been developed involving creation of rFLG-NC ink that can be deposited on various substrates. It has been observed that a successful synthesis of a free-standing composite coating is possible with the mass ratio of rFLG:NC at least 9:1 of which resistivity is on the order of approximate 10 ohm-centimetres in dependence from temperature and surrounding atmosphere. Sensor electrode was prepared by simple dip-coating method and the response to humidity, organic solvent vapours and nitrogen containing gases was measured and conclusion made that rFLG-NC coating is sensitive to many kinds of gases (cross-sensitive) what may result in false detecting or can be used to multi-sensor chips for artificial olfaction devices.Latvian Council of Science 2018-1/0194; 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 CAMART

Traffic induced air pollution modeling: Scenario analysis for air quality management in street canyon

This study was supported by the Riga City research project DMV-17-60-lī-03.02.2017. The authors wish to thank the Riga City Council and Latvian Environment, Geology and Meteorology Centre for data used in this study.Mathematical models are intensively used in environmental science for various reasons - status quo assessment, statistical modeling, forecasting, and planning, scenario analysis. Traffic flow and related atmospheric pollution modeling is one of the most complex challenges because of various aspects, - wide versa of affecting factors, daily, diurnal, weekly, monthly and yearly variability and non-stability of them. In the present study atmospheric model OSPM (Operational Street Pollution Model) is used to calculate NOx and PM10 concentration levels in the historical center (street canyon) of the city of Riga (Latvia) in order to make further assumptions (e.g., for the traffic load) for minimizing traffic induced air pollution in street canyons. In total five different scenarios were analyzed involving prioritizations of public transport, restrictions for old private cars or flow limitations in traffic jam situations during working days.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 CAMART

TRAFFIC FLOW HYPOTHETICAL MODELLING FOR AIR QUALITY IMPROVEMENT AND PLANNING PURPOSES

The main emphasis of this research was to describe air pollution level and dispersion in a typical street canyon (Valdemara Street in Riga (Latvia) city centre), afterward to postulate potential development scenarios and perform modelling in order to understand the influence on air pollution level. For this purpose special mathematical model was used - Operational Street Pollution Model (OSPM), which was developed by the National Environmental Research Institute in Denmark. Following development scenarios were tested: (1) realistic environmentally friendly - decrease of traffic flow by 50 %, as according to street interviews about 36 - 50 % of drivers are ready to change driving habits from car to bicycle; (2) strictly limited – “green light” for public transport, but restrictions for old private cars, flow speed limitations.  

AB Initio Calculations of CU N @Graphene (0001) Nanostructures for Electrocatalytic Applications

Funding from European Union’s Horizon 2020 Research and Innovation Programme project under grant agreement No. 768789 is greatly acknowledged.Substitution of fossil-based chemical processes by the combination of electrochemical reactions driven by sources of renewable energy and parallel use of H 2 O and CO 2 to produce carbon and hydrogen, respectively, can serve as direct synthesis of bulk chemicals and fuels. We plan to design and develop a prototype of electrochemical reactor combining cathodic CO 2 -reduction to ethylene and anodic H 2 O oxidation to hydrogen peroxide. We perform ab initio calculations on the atomistic 2D graphene-based models with attached Cu atoms foreseen for dissociation of CO 2 and H 2 O containing complexes, electronic properties of which are described taking into account elemental electrocatalytical reaction steps. The applicability of the model nanostructures for computer simulation on electrical conductivity of charged Cu n /graphene (0001) surface is also reported.Horizon 2020 Framework Programme 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 CAMART

LESSONS FROM TEACHING RENEWABLES: DOMESTIC AND CROSS-BORDER EDUCATION ACTION – LATVIAN SOLAR CUP

From 2008 the education action – Latvian Solar Cup – is organized in University of Latvia. In this event, intended for pupils andstudents, the basics of one of the types of renewable energy – solar photovoltaic – are taught, and pupils from 5th to 12th classes arebeing taught, and students – those who teach. Lectures about renewable technologies are organized for pupils, and materials aredistributed them for homework – to built up just a solar-powered vehicle. First Solar Cup became with an active participation ofCzech colleagues (University of Ostrava) and their experience in organizing similar initiatives. Over the next few years the Germancolleagues from the University of Kassel (Germany) shared with their experience from German Solar Cup activities.KEY WORDS: renewable energy technologies, solar cup, education action, photovoltaics

Prospects of Decarbonizing Industrial Areas in the Baltic States by Means of Alternative Fuels

This work has been supported by the National Research Programme, project “Trends, Challenges and Solutions of Latvian Gas Infrastructure Development” (LAGAS), No. VPP-EM-INFRA-2018/1-0003.All three Baltic States have reached good fi gures regarding the change in total greenhouse gas emissions from transport during 1990-2017. Particularly successful is Lithuania, showing a negative value of -2.7%. Latvia considerably lags behind Estonia (+15.1% vs. +1.5%). Amid the achievement of Latvian scientists, engineers and merchants, the authors point out the work of Lithuanian engineers who investigated how gaseous hydrogen affects the parameters of diesel internal combustion engine. Important to note that in the Baltic States, the activities of inland waterway vessels and the shunting locomotives are concentrated in only a few main cities. Regarding that, Baltic scientists and environment specialists nowadays are developing plans also for local air pollution decreasing, which can be carried out in particular cities or industrial areas, thereby allowing for improvements in air cleanliness and the ecological situation in concerned local area. A numerical estimation shows that applying the NYSMART technology, introduced in this paper, will make areas of active action of the high-volume diesels cleaner in the same amount as gained by photosynthesis of the urban green flora. In recent years, the developed technology of hydraulic piston compression allows producing numerous different vehicle fueling appliances for the CNG/bio-CNG fuel. The further development of this technology means the producing of various solutions, applicable at biogas/biomethane production sites, for CNG/bio-CNG compression, transportation and fast natural gas vehicles refueling in a cost effective and convenient way. The hydraulic piston compression and NYSMART have a potential in small and medium-scale technologies and therefore need to be developed further for applications with hydrogen. Production of biomethane and green hydrogen is delayed by the lack of state aid programmes in the Baltic States. Lithuania is on the way to change the situation in the coming years, with one of the first biomethane gas production plants due to be built near Panevėžys, in Šilagalys near the Via Baltica motorway. Summing up all aspects, the preconditions for the use of alternative fuels in the Baltic States are similar, allowing one to learn from other’s experience and to consider joint projects. © 2022. Journal of Ecological Engineering All Rights ReservedNational Research Programme VPP-EM-INFRA-2018/1-0003; Institute of Solid State Physics, University of Latvia 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

Nafion® and polyaniline composite modification with Li and Mg ions

Funding from European Union`s Horizon 2020 Research and Innovation Program project under grant agreement No 768789 is greatly acknowledged.Modification of Nafion®-based samples with polyaniline (PANI) and positive charged ions could potentially allow achieving good proton conductivity at higher working temperatures what is observed in typical polymer electrolyte membrane fuel cells. In this work Nafion® polymer was modified with 1% polyaniline emeraldine salt and Li and Mg ions containing solutions. The influence of activation process and the type of ions on composites' proton conductivity was investigated. To define the best composition the physiochemical properties of synthesized materials were determined by the means of thermogravimetric analysis, impedance spectroscopy, determination of water absorption and its kinetics, and FTIR. From the original samples the best results of σ=155 mS/cm were shown by Nafion®/PANI membrane what was modified by Li+ reduction solution. This membrane also had better thermal characteristic compared to other researched samples: membrane degradation starts on higher temperature interval.Horizon 2020 Research and Innovation Program project under grant agreement No 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 CAMART