Audrius Drabavicius - Academia.edu (original) (raw)

Papers by Audrius Drabavicius

Chemija, Apr 21, 2020

The carbon supported manganese(IV)-cobalt (II/III) oxides nanoparticles labelled as MnO 2-Co 3 O ... more The carbon supported manganese(IV)-cobalt (II/III) oxides nanoparticles labelled as MnO 2-Co 3 O 4 /C nanocomposites have been prepared by a simple one-step microwave-assisted heating method using different precursor materials. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and inductively coupled plasma optical emission spectroscopy (ICP-OES) have been used for the characterization of morphology, structure and composition of the synthesized nanocomposites, whereas the electrochemical performance of the prepared nanocomposites has been evaluated by using cyclic voltammetry (CV). It was determined that the use of different precursor materials for the synthesis of the carbon supported MnO 2 and Co 3 O 4 nanocomposites results in a different morphology of the prepared substances. A high specific capacitance (C s) of 658.8 F g −1 at a scan rate of 10 mV s −1 in a 1 M Na 2 SO 4 solution has been obtained for the MnO 2-Co 3 O 4 /C-2 nanocomposite that has a spherical shape of nanoparticles. Moreover, it significantly outperforms the MnO 2-Co 3 O 4 /C-1 nanocomposite that has a lamellar shape of nanoparticles.

ECS transactions, Nov 24, 2015

In this study a series of PtRuCo/GR with the different molar ratios were prepared by microwave-as... more In this study a series of PtRuCo/GR with the different molar ratios were prepared by microwave-assisted heating of the reaction mixture consisting of H2PtCl6, RuCl3, CoCl2 and ethylene glycol. The Transmission Electron Microscopy and Inductively Coupled Plasma Optical Emission Spectroscopy were employed to characterize the synthesized PtRuCo/GR catalysts. The electrocatalytic activity of the synthesized catalysts towards the oxidation of methanol was investigated by means of cyclic voltammetry and chronoamperometry. It was found that the PtRuCo/GR catalysts with the Pt:Ru:Co molar ratios equal to 1:2:2, 1:1.7:5.6 and 3.5:1:23 were prepared. The PtRuCo/GR catalyst with the Pt:Ru:Co molar ratio equal to 3.5:1:23 has a higher electrocatalytic activity towards the oxidation of methanol in acidic medium as compared with that of other synthesized catalysts.

ACS Applied Materials & Interfaces, Dec 12, 2018

Inorganic cesium lead halide perovskite nanowires, generating laser emission in the broad spectra... more Inorganic cesium lead halide perovskite nanowires, generating laser emission in the broad spectral range at room temperature and low threshold, have become powerful tools for the cutting-edge applications in the optoelectronics and nanophotonics. However, to achieve high-quality nanowires with the outstanding optical properties, it was necessary to employ long-lasting and costly methods of their synthesis, as well as postsynthetic separation and transfer procedures that are not convenient for large-scale production. Here we report a novel approach to fabricate high-quality CsPbBr3 nanolasers obtained by rapid precipitation from dimethyl sulfoxide solution sprayed onto hydrophobic substrates at ambient conditions. The synthesis technique allows producing the well-separated nanowires with a broad size distribution of 2-50 μm in 5-7 min, being the fastest method to the best of our knowledge. The formation of nanowires occurs via ligand-assisted reprecipitation triggered by intermolecular proton transfer from (CH3)2CHOH to H2O in the presence of a minor amount of water. The XRD patterns confirm an orthorhombic crystal structure of the as-grown CsPbBr3 single nanowires. Scanning electron microscopy images reveal their regular shape and truncated pyramidal end facets, while high-resolution transmission electron microscopy ones demonstrate their single-crystal structure. The lifetime of excitonic emission of the nanowires is found to be 7 ns, when the samples are excited with energy below the lasing threshold, manifesting the low concentration of defect states. The measured nanolasers of different lengths exhibit pronounced stimulated emission above 13 μJ cm-2 excitation threshold with quality factor Q = 1017-6166. Their high performance is assumed to be related to their monocrystalline structure, low concentration of defect states, and improved end facet reflectivity.

ECS Meeting Abstracts, 2020

In recent decades, alkaline direct alcohol fuel cells have been interested due to their advantage... more In recent decades, alkaline direct alcohol fuel cells have been interested due to their advantages over hydrogen fuel cell. Alcohols such as methanol and ethanol are the most common types of fuel used in direct liquid-feed fuel cells however alternative alcohols are increasingly being investigated. One of the choices for alkaline alcohol fuel cell is ethylene glycol. Ethylene glycol in an alkaline medium generates, as intermediates, oxalates, glyoxylate, glycolate, glycolaldehyde, glyoxal and carbon dioxide and it is considered an energy carrier for fuel cells. The importance of this fuel is attributed to several factors: low molecular weight, biomass origin, high energy density, high boiling point and lower toxicity than methanol. One more challenge is to find the most efficient electrocatalysts for various fuel oxidation reaction which could replace platinum in fuel cell anode materials in relation to its limited resources and high price. Lately, the most research is based on the ...

Catalysts, 2021

This paper describes the investigation of electrocatalytic activity of the AuCeO2/C catalyst, pre... more This paper describes the investigation of electrocatalytic activity of the AuCeO2/C catalyst, prepared using the microwave irradiation method, towards the oxidation of sodium borohydride and oxygen reduction reactions in an alkaline medium. It was found that the obtained AuCeO2/C catalyst with Au loading and electrochemically active surface area of Au nanoparticles (AuNPs) equal to 71 µg cm−2 and 0.05 cm2, respectively, showed an enhanced electrocatalytic activity towards investigated reactions, compared with the Au/C catalyst with an Au loading and electrochemically active surface area of AuNPs equal to 78 µg cm−2 and 0.19 cm2, respectively. The AuCeO2/C catalyst demonstrated ca. 4.5 times higher current density values for the oxidation of sodium borohydride compared with those of the bare Au/C catalyst. Moreover, the onset potential of the oxygen reduction reaction (0.96 V) on the AuCeO2/C catalyst was similar to the commercial Pt/C (0.98 V).

Journal of Physics: Conference Series, 2021

Tetramethyl orthosilicate and triethoxyphenylsilane, which contains hydrophobic phenyl groups, we... more Tetramethyl orthosilicate and triethoxyphenylsilane, which contains hydrophobic phenyl groups, were used as a silica (SiO2) source in a modified ligand-assisted reprecipitation synthesis approach for the fabrication of water-stable perovskite nanocrystals. Hydrolysis-condensation reaction of tetramethyl orthosilicate and triethoxyphenylsilane results in a formation of 3D siloxane network. Employing triethoxyphenylsilane in the synthesis enhances the hydrophobic properties of the SiO2 shell, which increases the stability of perovskites in aqueous medium. The stability of the CsPbBr3@SiO2 nanocrystals was estimated after 24 h of water exposure by the photoluminescence measurements at different time points. The synthesized CsPbBr3@SiO2 nanocrystals were visualized during in vitro experiments with murine melanoma B16-F10 cells. Hence, the potential of CsPbBr@SiO2 nanocrystals for bioimaging purposes was observed.

Chemija, 2020

AuCeO2/C and Au/C catalysts were obtained by adsorption of AuNPs on the CeO2/C and pure carbon (C... more AuCeO2/C and Au/C catalysts were obtained by adsorption of AuNPs on the CeO2/C and pure carbon (C) substrates from an Au colloidal solution. It has been found that AuNPs of ca. 50 nm in size were adsorbed on the surfaces of CeO2/C and C; however, electrocatalytic activity of the investigated AuCeO2/C and Au/C catalysts was different. Ethylene glycol oxidation current density values are ca. 3 times higher on the AuCeO2/C catalyst as compared to those of the bare Au/C catalyst. Moreover, the AuCeO2/C catalyst showed more positive onset potentials, as well as higher current in the mixed-kinetic-diffusion region towards the oxygen reduction reaction in an alkaline medium compared to that of the Au/C catalyst.

RSC Advances, 2016

The size of CeO2 nanoparticles can be controlled by VUV irradiation time and post annealing tempe... more The size of CeO2 nanoparticles can be controlled by VUV irradiation time and post annealing temperature.

Advances in Science and Technology, 2010

Niobium and nitrogen co-doped SrTiO3 possessing excellent visible light responsive photocatalytic... more Niobium and nitrogen co-doped SrTiO3 possessing excellent visible light responsive photocatalytic activity was successfully synthesized by microwave-assisted solvothermal reaction using SrCl2.6H2O, Ti(OC3H7)4, NbCl5 and hexamethylenetetramine in KOH aqueous solution. The photocatalytic activity was determined by DeNOx ability using LED lamps with the wavelengths of 627 nm (red), 530 nm (green), 445 nm (blue) and 390 nm (UV). The photocatalytic activity of SrTiO3 for DeNOx ability in visible light region could be improved by co-doping Nb5+ and N3-. The excellent visible light photocatalytic activity of this substance may be due to the generation of a new band gap that enables to absorb visible light and decrease in the lattice defects which acts as a recombination center of photoinduced electrons and holes.

Ceramics International, Nov 1, 2022

Chemija, Feb 26, 2020

MnO 2 /C nanocomposites have been prepared using a simple onestep microwave heating method by app... more MnO 2 /C nanocomposites have been prepared using a simple onestep microwave heating method by applying different concentrations of cationic surfactant-cetyl trimethylammonium bromide (CTAB). The morphology and composition of the prepared MnO 2 /C nanocomposites have been investigated using X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and inductively coupled plasma optical emission spectroscopy (ICP-OES). The electrochemical performance of the prepared nanocomposites has been analysed using cyclic voltammetry. It was found that a high specific capacitance (C s) of 742 F g −1 at a scan rate of 10 mV s −1 in a 1 M Na 2 SO 4 solution has been obtained for the MnO 2 /C nanocomposite that has the mass loading of 0.140 mg cm −2 and has been synthesized in the absence of CTAB. Meanwhile, the application of CTAB allowed the increase in the mass loading of MnO 2 in the nanocomposites. In the presence of CTAB, the highest value of 654 F g −1 at a scan rate of 10 mV s −1 has been obtained for MnO 2 /C that has the mass loading of 0.570 mg cm −2. This result confirmed a good performance of the prepared MnO 2 /C nanocomposites as the electrode material for supercapacitors.

Nano-Structures and Nano-Objects, Jul 1, 2018

h i g h l i g h t s • Cobalt ferrite nanoparticles against multidrug resistance pathogens. • Synt... more h i g h l i g h t s • Cobalt ferrite nanoparticles against multidrug resistance pathogens. • Synthesis and characterization of L-lysine and oleic acid stabilized cobalt ferrite nanoparticles. • While CoFe 2 O 4 @Ole Nps are more efficient antimicrobial agents than CoFe 2 O 4 @Lys Nps.

Materials, Nov 24, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Solid State Sciences, Oct 1, 2022

Applied Sciences

Laser ablation of a bulk graphite target in water using femtosecond laser pulses (pulse width ≤ 1... more Laser ablation of a bulk graphite target in water using femtosecond laser pulses (pulse width ≤ 190 fs) was performed to investigate the synthesis of polyynes and carbon-based nanomaterials and compare them with the well-studied cases of longer pulse (picosecond or nanosecond) ablations. The laser ablation products were characterized using UV-vis absorption spectroscopy, Raman spectroscopy, X-ray diffraction, and transmission electron microscopy, whereas the induced plasma plumes were characterized using laser-induced breakdown spectroscopy. Carbon-based nanomaterials and short-chain polyynes (C6H2 and C8H2) are formed in the solutions as proven by their characteristic absorption band at ~262 nm and peaks in the region of 190–240 nm as well as at around 2100 cm−1 in the Raman spectra, respectively. Polyynes (C8H2) are present in the solutions that are produced under an ablation that is carried out in two intervals with a short pause between them, which is contrary to a continuous ab...

Materials

Herein, we present a synthesis route for high-efficiency nitrogen-doped carbon materials using kr... more Herein, we present a synthesis route for high-efficiency nitrogen-doped carbon materials using kraft pulping residue, black liquor, and wood charcoal as carbon sources. The synthesized nitrogen-doped carbon materials, based on black liquor and its mixture with wood charcoal, exhibited high specific surface areas (SSAs) of 2481 and 2690 m2 g−1, respectively, as well as a high volume of mesopores with an average size of 2.9–4.6 nm. The nitrogen content was approximately 3–4 at% in the synthesized nitrogen-doped carbon materials. A specific capacitance of approximately 81–142 F g−1 was achieved in a 1 M Na2SO4 aqueous solution at a current density of 0.2 A g−1. In addition, the specific capacitance retention was 99% after 1000 cycles, indicating good electrochemical stability.