Gediminas Niaura

Gediminas Niaura
Center for Physical Sciences and Technology | CPST · Organic Chemistry

PhD

About

325
Publications
57,962
Reads
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7,083
Citations
Additional affiliations
October 2010 - September 2016
Center for Physical Sciences and Technology
Position
  • Chief research associate
February 1999 - present
Vilnius University
Position
  • Chief research associate

Publications

Publications (325)
Article
The N-doped lignin-based carbon material has a promising activity and stability for its application as supercapacitor as well as non-noble metal-based catalysts for fuel cells, metal–air batteries .
Article
Photoelectrochemical conversion of solar energy into fuel products such as H2 or CH4 is an appealing, but technologically difficult process due to the simultaneous requirements for stability, efficiency and selectivity in the photoelectrode. One approach to design a photoelectrode with suitable properties is by using different materials that can co...
Article
Full-text available
Noble metal nanoparticles, specifically gold and silver, are extensively utilized in sensors, catalysts, surface-enhanced Raman scattering (SERS), and optical-electronic components due to their unique localized surface plasmon resonance (LSPR) properties. The production of these nanoparticles involves various methods, but among the environmentally...
Article
Full-text available
Carbonization of biomass residues followed by activation has great potential to become a safe process for the production of various carbon materials for various applications. Demand for commercial use of biomass-based carbon materials is growing rapidly in advanced technologies, including in the energy sector, as catalysts, batteries and capacitor...
Article
This research focuses on a straightforward synthesis method for laser-induced graphene using green (532 nm) and UV (355 nm) picosecond laser irradiation of graphene oxide dispersion. Structural analysis revealed that the laser operating at 355 nm is more favorable to producing a product with a higher content of the restored sp2 network, a higher gr...
Article
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Amphiphilic diblock copolymers containing a block of 2-methacryloyloxyethyl phosphorylcholine (MPC) with unique properties to prevent nonspecific protein adsorption and enhance lubrication in aqueous media and a block of dopamine methacrylamide (DOPMA) distinguished by excellent adhesion performance were synthesized by reversible addition fragmenta...
Article
Differently shaped periodic gold nanostructures on the surface of a thin metal film are fabricated utilizing the direct laser writing technique. The variations in the energy of single femtosecond pulses lead to the formation of morphologically distinct hollow nanostructures. The arrays that excite hybridized plasmonic modes are characterized by ele...
Article
Full-text available
Manganese- and nitrogen-doped carbon materials were produced using NaOH-activated wood char and wood-processing residues such as wood chips and black liquor and evaluated as oxygen reduction catalysts for further application in fuel cells or metal–air batteries. The elemental and chemical composition, with special attention given to types of nitrog...
Article
In this study, an efficient manganese (Mn) and nitrogen (N) co-doped carbon materials were prepared using the three raw materials, namely alder charcoal (Mn-N-C AC ), hydrothermally carbonised birch wood (Mn-N-C W ), and black liquor (Mn-N-C BL ). At first, biomass-based activated carbon materials were synthesized. Mn and N were co-doped in one ste...
Article
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The present study introduces a novel method for the synthesis of magneto-plasmonic nanoparticles (MPNPs) with enhanced functionality for surface-enhanced Raman scattering (SERS) applications. By employing pulsed laser ablation in liquid (PLAL) to synthesize plasmonic nanoparticles and wet chemistry to synthesize magnetic nanoparticles, we successfu...
Article
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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 a...
Article
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Generation of hybrid gold-silver nanoparticles from different metal ratios by thermal heating thin metal films on a glass surface with a nanosecond pulsed laser is presented. The optical properties of obtained nanoparticles are dependent on localized surface plasmon resonance (LSPR), which can be tuned in the range of 400–530 nm by varying the rati...
Article
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Nitrogen-doped activated carbons with controlled micro- and mesoporosity were obtained from wood and wastes via chemical processing using pre-treatment (pyrolysis at 500 °C and hydrothermally carbonization at 250 °C) and evaluated as oxygen reduction catalysts for further application in fuel cells. The elemental and chemical composition, structure...
Article
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Magneto-plasmonic nanoparticles were fabricated using a 1064 nm picosecond-pulsed laser for ablation of Fe/Au and Fe/Au/Fe composite thin films in acetone. Nanoparticles were characterized by electron microscopy, ultraviolet-visible (UV-VIS) absorption, and Raman spectroscopy. Hybrid nanoparticles were arranged on an aluminum substrate by a magneti...
Article
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This study focuses on fabricating cobalt particles deposited on graphitic carbon nitride (Co/gCN) using annealing, microwave-assisted and hydrothermal syntheses, and their employment in hydrogen and oxygen evolution (HER and OER) reactions. Composition, surface morphology, and structure were examined using inductively coupled plasma optical emissio...
Article
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Tethered bilayer lipid membranes (tBLMs) are increasingly used in biosensor applications where electrochemical impedance spectroscopy (EIS) is the method of choice for amplifying and recording the activity of membrane-damaging agents such as pore-forming toxins or disrupting peptides. While the activity of these biological agents may depend on the...
Article
Water-assisted ultrashort laser pulse processing of semiconductor materials is a promising technique to diminish heat accumulation and improve process quality. In this study, we investigate femtosecond laser ablation of deep trenches in GaAs, an important optoelectronic material, using water and ambient air environments at different laser processin...
Article
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Providing a 3D environment that mimics the native extracellular matrix is becoming increasingly important for various applications such as cell function studies, regenerative medicine, and drug discovery. Among the most critical parameters to consider are the scaffold’s complicated micro-scale geometry and material properties. Therefore, stereolith...
Article
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Tethered bilayer lipid membranes (tBLMs) are versatile platforms for the analysis of biochemical and biophysical processes at biological membranes. To control the stability and functional properties of these artificial constructions, molecular-level knowledge on the organization and structure is required. We used surface-enhanced infrared absorptio...
Article
Raman spectroscopic study of poly(N-methylaniline) as a thin layer deposited at a electrode was performed in an electrochemical system. A broad range of Raman excitation wavelengths from UV (325 nm) through blue (442 nm) and red (633 nm) to NIR (785 nm) were used. Two limiting redox forms, a reduced (leucoemeraldine) and a fully oxidized one, were...
Article
In this research, Cu2ZnSnS4 (CZTS) particles were successfully fabricated via the molten salt approach from the copper, zinc and tin sulphides as raw precursors. SEM analysis revealed that CZTS particles are tetragonal-shaped with sharp edges, smooth flat plane morphology, and crystal size varying from 10.8 to 28.7 µm. The phase and crystalline str...
Article
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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, resp...
Article
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Magnesium whitlockite (Mg-WH, Ca18Mg2(HPO4)2(PO4)12) is a promising candidate for biomedical application in bone regeneration; however, the fabrication of Mg-WH bioceramics by conventional methods is limited. Mg-WH is known to be...
Article
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Graphene-polypyrrole (GP) nanocomposites were synthesized by a wet-way protocol using a graphite bisulfate (GBS) precursor. Consequently, GBS, a type of graphite intercalation compound, was prepared in the presence of concentrated sulfuric acid in the presence of a potassium periodate oxidizer. Three different types of graphite precursor with parti...
Article
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To fabricate graphene-based high-frequency electronic and optoelectronic devices, there is a high demand for scalable low-contaminated graphene with high mobility. Graphene synthesized via chemical vapor deposition (CVD) on copper foil appears promising for this purpose, but residues from the polymethyl methacrylate (PMMA) layer, used for the wet t...
Article
Surface enhanced Raman spectroscopy (SERS) is a powerful tool for the investigation of low concentration analytes. To improve this method, magnetic nanoparticles were introduced to the system. Magnetic nanoparticles together with plasmonic silver or gold nanoparticles or shells not only enhance the SERS signal but also facilitate to focus the sampl...
Article
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The fabrication of nanostructured composite materials is an active field of materials chemistry. However, the ensembles of nanostructured titanium monoxide and suboxide species decorated with polyaniline (PANI) species have not been deeply investigated up to now. In this study, such composites were formed on both hydrothermally oxidized and anodize...
Article
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An essential amino acid, histidine, has a vital role in the secondary structure and catalytic activity of proteins because of the diverse interactions its side chain imidazole (Im) ring can take part in. Among these interactions, hydrogen donating and accepting bonding are often found to operate at the charged interfaces. However, despite the great...
Article
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The imidazole ring (Im) of histidine side chains plays a unique role in the function of proteins through covalent bonding with metal ions and hydrogen bonding interactions with adjusted biomolecules and water. At biological interfaces, these interactions are modified because of the presence of an electric field. Self-assembled monolayers (SAMs) wit...
Article
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Improving the performance of kesterite solar cells requires high-quality, defect-free CZTS(Se) films with a reduced number of secondary phases and impurities. Post-annealing of the CZTS films at high temperatures in a sulfur or selenium atmosphere is commonly used to improve the quality of the absorbing material. However, annealing at high-temperat...
Article
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We present a detailed study of the structural and electrical changes occurring in two graphene oxide (GO) samples during thermal reduction in the presence of malonic acid (MA) (5 and 10 wt%) and P2O5 additives. The morphology and de-oxidation efficiency of reduced GO (rGO) samples are characterized by Fourier transform infrared, X-ray photoelectron...
Article
We used vibrational sum-frequency generation (VSFG) spectroscopy to elucidate the possible effect of various levels of isotopic substitution (H/D) on the properties of the DPPC monolayer by probing DPPC/D2O interface. We found that deuteration of the choline group has a great impact on monolayer properties, while monolayers with deuterated alkyl ch...
Article
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Bismuth films with thicknesses between 6 and ∼30 nm were grown on Si (111) substrate by molecular beam epitaxy (MBE). Two main phases of bismuth — α-Bi and β-Bi — were identified from high-resolution X-ray diffraction (XRD) measurements. The crystal structure dependencies on the layer thicknesses of these films were analyzed. β-Bi layers were epita...
Poster
Full-text available
#SpecialIssue "New Vibrational Spectroscopy Developments of Material Characterization", edited by Dr. Gediminas Niaura (Center for Physical Sciences and Technology, Lithuania) and Dr. Martynas Talaikis (Institute of Biochemistry, Life Sciences Center, Vilnius University, Lithuania) is open to submissions! https://lnkd.in/gKfcDsFh Keywords #surface-...
Article
Recently, great attention has been focused on biomass-derived electrocatalysts for the oxygen reduction reaction (ORR). In the present study, the wood-derived nitrogen-doped carbon nanomaterials with graphene-like structures have been synthesized from wood biomass using a chemical activation method with NaOH to achieve a high specific surface area...
Article
N-doped carbons are widely used in the energy storage and conversion field because of their excellent electrical conductivity, high specific surface area, and superb electrochemical stability. Herein, high-efficiency carbon material has been derived using the kraft pulping residues – black liquor as the carbon source. The carbon material was prepar...
Article
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In the present research, graphene was synthesized directly on a Si(100) substrate via combining direct microwave plasma-enhanced chemical vapor deposition and protective enclosure. The graphene flake orientation was controlled using suitable synthesis conditions. We revealed that high processing temperatures and plasma powers promote vertical graph...
Article
Full-text available
The synthesis of magnetic particles triggers the interest of many scientists due to their relevant properties and wide range of applications in the catalysis, nanomedicine, biosensing and magnetic separation fields. A fast synthesis of iron oxide magnetic particles using an eco-friendly and facile microwave-assisted solvothermal method is presented...
Article
In this paper, two different reduced graphene oxide samples rGO_H and rGO_M derived, respectively, from the graphene oxide (GO) obtained using traditional and modified Hummers methods were synthesized. Thermal reduction of GO was performed in the presence of malonic acid (MA) and P2O5 additives. The prepared rGO samples were investigated as active...
Article
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Hafnium oxide (HfO2) films on silicon have the potential for application in photovoltaic devices. However, very little is known about the photoelectrochemical and protective properties of HfO2 films on Si. In this study, ultrathin films of HfO2 in the range of 15–70 nm were deposited on p-Si and Au substrates by atomic layer deposition (ALD). Grazi...
Article
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In this work, graphite intercalation compounds (GICs) were synthesized using three different oxidizers: (NH4)2S2O8, K2S2O8, and CrO3 with and without P2O5 as a water-binding agent. Furthermore, the samples obtained were heat-treated at 800 °C. Specimens were characterized by optical microscopy, Raman spectroscopy, Fourier transform infrared spectro...
Article
Full-text available
Vibrational spectroscopy provides the possibility for sensitive and precise detection of chemical changes in biomolecules due to development of cancers. In this work, label-free near-infrared surface enhanced Raman spectroscopy (SERS) was applied for the differentiation between cancerous and normal human bladder tissues via analysis of the extracel...
Article
A detailed study on Raman spectroelectrochemistry of poly(N-methylaniline) (PNMA) layer deposited at a gold electrode was performed. Raman spectra were excited by four different laser wavelengths: UV line at 325 nm, a blue line at 442 nm, a red line at 633 nm, and a NIR line at 785 nm in solutions of different pH ranging from 1 to 9, and at differe...
Article
Full-text available
Graphene research and technology development requires to reveal adsorption processes and understand how the defects change the physicochemical properties of the graphene-based systems. In this study, shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) and graphene-enhanced Raman spectroscopy (GERS) coupled with density functional theo...
Article
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The structural state and crystal structure of Lu(1−x)ScxFeO3 (0 ≤ x ≤ 1) compounds prepared by a chemical route based on a modified sol–gel method were investigated using X-ray diffraction, Raman spectroscopy, as well as scanning electron microscopy. It was observed that chemical doping with Sc ions led to a structural phase transition from the ort...
Article
The formation of kesterite (Cu2ZnSnS4) in a quartz tube furnace attached to a special separate chamber for evaporation of sulphur has been studied. Ar gas was used to transport the sulphur vapour to the reaction zone at the centre of tube furnace. A Cu-Zn-Sn (CZT) precursor on the Mo/glass substrate was formed by the electrochemical deposition of a...
Preprint
Full-text available
Sm-doped BiFeO3 compacted powders with composition across the morphotropic phase boundary region were prepared by sol-gel method. Crystal structure, morphology and magnetic state of the compounds were analyzed as a function of dopant concentration, temperature and external pressure using synchrotron and laboratory X-ray diffraction, electron micros...
Article
Full-text available
Surface-enhanced Raman spectroscopy (SERS) substrates fabricated using a repeated laser treatment of thin gold films are demonstrated. The presented SERS substrates consist of the gold nanoparticles, whose density and size depend on the used film thickness and number of treated films. The larger number of the treated gold film layers increases the...
Article
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Two kinds of natural silicate garnets from the known origin countries were investigated: pyralspites – pyrope (Russia), almandine (India), rhodolite (India), spessartine (India), blue colour-change garnet (Sri Lanka), and ugrandites – andradite (Russia), demantoid (Russia), topazolite (Russia), rainbow garnet (Japan), grossular (Kenya-Tanzania), co...
Article
Sm-doped BiFeO3 compacted powders with composition across the morphotropic phase boundary region were prepared by sol-gel method. Crystal structure, morphology and magnetic state of the compounds were analyzed as a function of dopant concentration, temperature and external pressure using synchrotron and laboratory X-ray diffraction, electron micros...
Article
La:BaSnO3 has recently emerged as an outstanding perovskite oxide material due to its high electron mobility. To-date, lower electron mobility in thin films compared to the single-crystal are discussed in terms of the presence of dislocations, nearly neglecting the role of cation nonstoichiometry. However, by controlling Sn/Ba compositional ratio,...