Energetska tranzicija i vodonična evolucija

The escalating concerns over climate changes and environmental disturbances resulting from anthropogenic influence have propelled the scientific community to seek efficient models for the energy transition. Hydrogen emerges as a promising energy carrier with the potential to replace fossil fuels and mitigate global warming, a pressing threat to life on Earth. This research paper primarily focuses on the electrolytic production of hydrogen, deemed the environmentally acceptable method for this purpose. The central emphasis lies in enhancing the electrodes utilized in this process to elevate the significance of the Hydrogen Evolution Reaction (HER). By improving HER, a pivotal step in the hydrogen production process, the trajectory of civilization's evolution can be positively influenced.Sve veća zabrinutost zbog klimatskih promena i ekoloških poremećaja koji su rezultat antropogenog uticaja naterali su naučnu zajednicu da traži efikasne modele za energetsku tranziciju. Vodonik se pojavljuje kao perspektivan nosilac energije sa potencijalom da zameni fosilna goriva i ublaži globalno zagrevanje, goruću pretnju životu na Zemlji. Ovaj istraživački rad se prvenstveno fokusira na elektrolitičku proizvodnju vodonika, koja se smatra ekološki prihvatljivom metodom za ovu svrhu. Centralni naglasak je na poboljšanju elektroda koje se koriste u ovom procesu kako bi se podigao značaj reakcije evolucije vodonika (HER). Poboljšanjem HER, ključnog koraka u procesu proizvodnje vodonika, može se pozitivno uticati na putanju evolucije civilizacije

In-situ grafting of Fe and Cu nanoparticles on carbon for electrolytic hydrogen production

In order to reduce air pollution by green-house gases released during fossil fuels combustion, hydrogen has been suggested as an alternative, clean fuel [1]. The most promising method of obtaining green hydrogen (and oxygen) is electrolytic water splitting [2]. For splitting process to be efficient, it is necessary to useelectrocatalysts with high activity, but they should also be economically accessible. Ionic liquids are used in the most diverse fields of sciencedue to their unique physical and chemical properties, and in this regard, they can be used for the development of electrocatalystsby direct carbonization [3]. Within this study, carbon catalysts doped with iron and copper (Fe/C, Cu/C and FeCu/C) were prepared by carbonization of ionic liquids containing the corresponding metal and characterized for the hydrogen evolution reaction (HER) in alkaline (8 M KOH) media. Electrochemical measurements were made by cyclic voltammetry (CV), linear cyclic voltammetry (LSV), electrochemical impedance spectroscopy (EIS) and chronoamperometry (CA). All electrocatalysts showed good activity for HER. Tafel slope (b) values of -132, 155 and -151 mV dec-1 (Table 1) were obtained for HER at 25 oC for Fe/C, Cu/C and FeCu/C, respectively. Also, the exchange current density (j0) was determined and the values ranged from 1.28 to 2.94 10-2 mAcm-2. The results (Table 1) show that Fe/C, Cu/C and FeCu/Care promisingelectrocatalysts for hydrogen gas production by water splitting.Ninth Symposium Chemistry and Environmental Protection : June 4-7, Kladovo, 2023

Na zelenom putu inovacija – vodonik iz laserski potpomognute alkalne elektrolize

The dominant problem that needs to be solved today is the issue of energy sources and how to use them, which must be ecological and sustainable - in a word, green. As the best candidate for a global solution to this problem, hydrogen produced electrolytically stood out as a green fuel with no carbon footprint. However, for a hydrogen-based economy to have a realistic and sustainable perspective in the future, it largely depends on its efficient and economically viable production that would meet the market's needs. Special attention in this paper is devoted to the influence of laser radiation on the possibility of improving the process of alkaline electrolysis for obtaining hydrogen, as well as on increasing the amount of separated hydrogen when the electrolytic cell is directly irradiated with a laser beam during the electrolysis process itself. After the experiments, it was determined that the application of direct irradiation of the electrolyte with a green laser at 532 nm wavelength significantly increases the amount of hydrogen produced and reduces the voltage of the electrolytic process, which is directly related to the increase in the energy efficiency of the overall hydrogen production process.Dominantan problem koji danas treba rešiti je pitanje energenata i načina njihove upotrebe koji moraju biti ekološki i održivi – jednom rečju zeleni. Kao najbolji kandidat za globalno rešenje ovog problema istakao se vodonik proizveden elektolitičkim putem, kao zeleno gorivo bez ugljeničnih otisaka. Da bi ekonomija zasnovana na vodoniku imala realnu i održivu perspektivu u budućnosti, u velikoj meri zavisi od njegove efikasne i ekonomski podobne proizvodnje koja bi zadovoljila potrebe tržišta. Posebna pažnja u ovom radu posvećena je uticaju laserskog zračenja na mogućnost poboljšanja procesa alkalne elektrolize za dobijanje vodonika, kao i na povećanje količine izdvojenog vodonika pri direktnom ozračivanju elektrolitičke ćelije laserskim snopom tokom samog procesa elektrolize. Nakon izvršenih eksperimenata utvrđeno je da se primenom direktnog ozračivanja elektrolita zelenim laserom talasne dužine 532 nm u značajnoj meri povećava količina proizvedenog vodonika i smanjuje napon elektrolitičkog procesa, što je u direktnoj vezi sa povećanjem energetske efikasnosti ukupnog procesa dobijanja vodonika

Applicability of Construction and Demolition Waste in Geopolymers – A Screening Test

In this study, the applicability of construction and demolition waste (C&DW) in geopolymerization technology was investigated. The C&DW components, concrete and solid bricks, were collected from demolition sites in Belgrade, Republic of Serbia. The concrete sample came from a demolished fifty-year-old construction road, while the remains of solid bricks originated from a 1930s building. Prior to mechanical testing, the C&DW components were characterized by XRD analysis for their mineralogical composition. The results showed that the concrete waste consisted mainly of quartz (SiO2) and calcite (CaCO3), while the brick waste sample contained anorthite from the feldspar group (CaAl2Si2O8), wollastonite (Ca0.957Fe0.043O3Si) and mullite (Al2.4O4.8SiO6). The mechanical properties were examined using the screening method on three geopolymer mixtures, one of each mixture of concrete and brick powders and a mixture of both C&DW components. According to the standard SRPS EN 12390-3:2010 for cubic samples, the geopolymer samples were prepared with alkaline activators for testing the compressive strength as the dominant parameter in the mortar and concrete evaluation. The compressive strength values increased in the range of 2.4 MPa for concrete, 10.2 MPa for brick, and 10.8 MPa for the mixed geopolymer sample. The low compressive strength result of the concrete sample was the consequence of the mineral composition, i.e., the absence of aluminosilicate. However, the brick and the sample with a combination of both types of waste showed moderately satisfactory compressive strength, which could be the starting point for further investigations

Synthesis and Properties of Ni-doped Goethite and Ni-doped Hematite Nanorods

Ni-doped goethite (α-FeOOH) nanorods were synthesized from mixed Fe(III)-Ni(II) nitrate solutions with various Ni/(Ni+Fe) ratios (0, 5, 10, 20, 33 and 50 mol % Ni) by hydrothermal precipitation in a highly alkaline medium using the strong organic alkali, tetramethylammonium hydroxide (TMAH). Ni-doped hematite (α-Fe2O3) nanorods were obtained by calcination of Ni-doped goethite nanorods at 400 °C. The Ni 2+ -for-Fe 3+ substitution in goethite and hematite was confirmed by determination of the unit cell expansion (due to the difference in the ionic radii of Fe 3+ and Ni 2+ ) using XRPD and determination of the reduction of a hyperfine magnetic field (due to the difference in magnetic moments of Fe 3+ and Ni 2+ ) using Mössbauer spectroscopy. Single-phase goethite nanorods were found in samples containing 0 or 5 mol % Ni. A higher Ni content in the precipitation system (10 mol % or more) resulted in a higher Ni 2+ -for-Fe 3+ substitution in goethite, and larger Ni-doped goethite nanorods, though with the presence of low crystalline Ni-containing ferrihydrite and Ni ferrite (NiFe2O4) as additional phases. Significant changes in FT-IR and UV-Vis-NIR spectra of prepared samples were observed with increasing Ni content. Electrochemical measurements of samples showed a strong increase in oxygen evolution reaction (OER) electrocatalytic activity with increasing Ni content. © 2018 Croatian Chemical Society. All Rights Reserved

Ab Initio Study of Graphene Interaction with O-2, O, and O-

A systematic ab initio (DFT-GGA) study of adsorption of various oxygen species on graphene has been performed in order to find out general trends and provide a good starting point to analyze the oxidation of more complex carbon materials. Particular attention was paid to finding an appropriate supercell model. According to our findings, atomic O is characterized by stable adsorption on graphene and very strong adsorption on defective graphene. On the other hand, O-2 does not adsorb on graphene and is allowed to diffuse freely to the defect, where it is expected to dissociate into two strongly adsorbed O atoms. The obtained results were compared with available theoretical data in the literature and good agreement was achieved

Supplementary material for the article: Milošev, M. Z.; Jakovljević, K.; Joksović, M. D.; Stanojković, T.; Matić, I. Z.; Perović, M.; Tešić, V.; Kanazir, S.; Mladenović, M.; Rodić, M. V.; et al. Mannich Bases of 1,2,4-Triazole3-Thione Containing Adamantane Moiety: Synthesis, Preliminary Anticancer Evaluation, and Molecular Modeling Studies. Chemical Biology and Drug Design 2017, 89 (6), 943–952. https://doi.org/10.1111/cbdd.12920

Supporting Information: [https://doi.org/10.1111/cbdd.12920]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2482]Related to accepted version: [http://cherry.chem.bg.ac.rs/handle/123456789/3221

Supplementary material for the article: Milošev, M. Z.; Jakovljević, K.; Joksović, M. D.; Stanojković, T.; Matić, I. Z.; Perović, M.; Tešić, V.; Kanazir, S.; Mladenović, M.; Rodić, M. V.; et al. Mannich Bases of 1,2,4-Triazole3-Thione Containing Adamantane Moiety: Synthesis, Preliminary Anticancer Evaluation, and Molecular Modeling Studies. Chemical Biology and Drug Design 2017, 89 (6), 943–952. https://doi.org/10.1111/cbdd.12920

Supporting Information: [https://doi.org/10.1111/cbdd.12920]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2482]Related to accepted version: [http://cherry.chem.bg.ac.rs/handle/123456789/3221

Energy consumption of the electrolytic hydrogen production using Ni-W based activators-Part I

The aim of this work is to investigate the energy consumption of alkaline electrolyser with the in situ added ionic activators. Several concentrations of nickel and tungsten based ionic activators were used in the same alkaline electrolyser, and the energy consumption was calculated and compared to conventional electrolyte. The electrolyser operated at several current densities and temperatures, in order to obtain the optimal concentration of the ionic activators. We have obtained lowering of the energy needed to produce certain amounts of hydrogen for about 15% compared to standard electrolyte, just using simplified process of the in situ activation with Ni and W based ionic activators. Alkaline electrolyser operated with the selected concentration of d-metals has shown long term stability under industrial conditions. (C) 2011 Elsevier B.V. All rights reserved