Maria Shipochka

Bulgarian Academy of Sciences | BAS · Institute of General and Inorganic Chemistry

In order to improve the specific capacity of intercalation electrodes for sodium-ion batteries, it is necessary to identify materials capable of storing Na⁺ ions by activating multi-electron redox reactions. Herein, we report a NaFeVPO4(SO4)2 compound as a multi-electron electrode that combines the most abundant Fe and V ions, having multiple oxida...

Novel fibrous cellulosic substrates impregnated with meta-polybenzimidazole (PBI)-stabilized carbon nanotubes/zinc oxide with different weight content of ZnO and with the use of dimethylacetamide as dispersant media. The pristine ZnO nanoparticle powder was prepared by plant extract-mediated synthesis using Vaccinium vitis-idaea L. The green synthe...

The introduction of new regulations needs to develop eco-friendly systems to prevent corrosion. In this work, a natural corrosion inhibitor caffeine (CAF) was encapsulated in polysaccharide-based nanoparticles, capable of the responsive release of CAF during corrosion. The nanoparticles were prepared using electrostatic complexation between two nat...

In this paper, hybrid coatings based on ZnO dispersion in water soluble chitosan oligosaccharides (COS) as dispersion medium were prepared. The obtaining procedure of anti-corrosion hybrid zinc-based coatings containing COS coated ZnO particles in the metal matrix has been described. The available ZnO particles coated with COS were observed by TEM...

The key technological implementation of sodium-ion batteries is converting biomass-derived hard carbons into effective anode materials. This becomes feasible if appropriate knowledge of the relations between the structure of carbonized biomass products, the mineral ash content in them, and Na storage properties is gained. In this study, we examine...

This work presents the enhanced corrosion resistance of newly developed two-layer composite coatings deposited on low-carbon steel: electrodeposited zinc alloy coatings (Zn–Ni with 10 wt.% Ni (ZN) or Zn–Co with 3 wt.% Co (ZC), respectively) and a top ZrO2 sol–gel layer. Surface morphology peculiarities and anti-corrosion characteristics were examin...

New Poly(lactic acid)/Polyvinylpyrrolidone, containing green synthesized Hydrozincite (GHZ) emulsion elec-trospun fibers and drop spread films possessing antibacterial and photocatalytic activity were prepared. The PLA/PVP/GHZ films possess higher photocatalytic efficiency towards Malachite Green (MG) dye discoloration (85%) than that of the fibers...

This study aimed to present the differences in the corrosion properties and protective ability of two bi-layer systems obtained on low-carbon steel in a model corrosive medium of 5% NaCl solution. These newly developed systems consist of Zn-Co (3 wt.%) or Zn-Ni (10 wt.%) alloy coatings as under-layers and a very thin TiO2 sol-gel film as a top-laye...

The presented investigations demonstrate the corrosion behavior and protective ability of hybrid zinc coatings specially designed for combined protection of low-carbon steel from localized corrosion and biofouling. Polymer-modified copper oxide (CuO) nanoparticles as widely used classic biocide are applied for this purpose, being simultaneously ele...

Diamond-like carbon (DLC) films were deposited at 300 °C, 400 °C and 500 °C on 304 L stainless steel substrates by electron-beam physical vapor deposition. The obtained coatings were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy and X-ray photo electron spectroscopy (XPS). The FTIR results demonstrate the prese...

Diamond-like carbon (DLC) films were deposited at room temperature, 100°C, 200°C, 300°C and 400°C on Si substrates by means of electron-beam physical vapor deposition. The obtained coatings were characterized by Fourier Transform Infrared Spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The FTIR results demonstrate the presence of sp...

Samarium doped (0.5-5 at.%) ZrO2 films with high surface and optical quality were obtained by sol-gel method using inorganic zirconium precursor. The morphology and roughness of the samples were investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). A phase transition following the doping with Sm³⁺ ions was registered...

In this study, we present the results of the effect of duplex surface modification of 304-L stainless steel substrates by an electron-beam treatment (EBT) and subsequent deposition of diamond-like carbon coatings on the surface roughness and corrosion behavior. During the EBT process, the beam power was varied from 1000 to 1500 W. The successful de...

In our study, transparent and conductive films of NiOx were successfully deposited by sol-gel technology. NiOx films were obtained by spin coating on glass and Si substrates. The vibrational, optical, and electrical properties were studied as a function of the annealing temperatures from 200 to 500 °C. X-ray Photoelectron (XPS) spectroscopy reveale...

Enhanced corrosion efficiency of low-carbon steel was achieved by newly developed hybrid multilayers, composed of low-carbon steel coated with an electrodeposited zinc sublayer (1 µm), a chitosan (CS) middle layer and ZrO2 coating by the sol–gel method (top-layer). The middle chitosan layer was obtained by dipping galvanized steel substrate in 3% t...

Dense, highly textured, hydrophobic ZrO2-TiO2 (1:1) coatings with amorphous structure were prepared using the sol-gel method. Both organic and inorganic zirconium precursor salts were used. The present study dealt with the investigation of their protective ability in a selected model corrosive medium with chloride ions as corrosion activators. The...

Biomass-derived carbonaceous materials are considered as one of the most perspective electrodes for symmetric supercapacitors working with alkaline-basic electrolytes. However, they still exhibit lower energy density. Herein, we demonstrate the capacitance performance of the commercial carbon product (YP-50F, “Kuraray Europe” GmbH), obtained from c...

Sol gel TiO2-ZrO2 composite films were dip coated on stainless steel substrates and treated at 300, 400 and 500oC. The morphology and surface features were examined by Scanning electron microscopy (SEM) and X ray photoelectron spectroscopy (XPS). Xray diffraction analyses (XRD) was applied to investigate the phase composition. The corrosion resista...

CaWO4 nanoparticles were successfully obtained by direct mechanochemical synthesis. In the search of new and advanced catalysts, the CaWO4 has been modified by Pd and characterized by various techniques such as: N2-physisorption, XRD, IR, TEM, XPS, TPR and TPD. The results from the instrumental methods confirmed that CaWO4 can be formed at room tem...

The presence of triple phase TiO2 new mixture (Magneli of higher order homologous series, brookite and anatase) containing P dopant ensures positive changes in the structure, in the phase composition and in the chemical composition. These changes explained the reasons for the enhanced UV/Vis photocatalytic efficiency towards oxidative degradation o...

The present work explores in detail the effect of alkaline-basic electrolytes on the capacitance performance of biomass-derived carbonaceous materials used as electrodes in symmetric supercapacitors. The proof-of-concept is demonstrated by two commercial carbon products (YP-50F and YP-80F, Kuraray Europe GmbH, Vantaa, Finland), obtained from coconu...

The present work explores in detail the effect of alkaline-basic electrolytes on the capacitance performance of biomass-derived carbonaceous materials used as electrodes in symmetric supercapacitors. The proof-of-concept is demonstrated by two commercial carbon products (YP-50F and YP-80F, Kuraray Europe GmbH, Vantaa, Finland), obtained from coconu...

Corrosion-resistant ZrO 2 coatings were deposited on stainless steel plates using organic (A) and inorganic (B) Zr precursors containing polyethylene glycol as structure directing agent. The dipping-drying cycles were repeated five times; the coatings were then treated at 500 °C. The samples were studied by atomic force microscopy (AFM), X-ray diff...

New and complex results on catalytic activity, thermal stability, effect of H 2 O and SO 2 on the Pd/La 2 O 3 -CeO 2 -Al 2 O 3 model system in methane combustion have been obtained. The catalyst characterization has been made by N 2 - physisorption, XRD, SEM/EDX, HRTEM, XPS, TPD, TPR and FTIR methods. The observed high activity is related to the st...

One-component CeO2 coatings and bi-component CeO2/ZrO2 multilayer coatings were obtained by a sol gel process. The phase composition, surface morphology and roughness of the samples were studied by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), Atomic force microscopy (AFM) and X-ray scanning electron microscopy (XPS). The co...

Transparent and homogeneous ZrO 2 films were obtained by sol-gel technique using different acids as stabilizing agents. Tetragonal ZrO 2 phase with small nanosized crystallites is characteristic for the studied films. The surface morphology of the samples is smooth and continuous without visible cracks. An average transmittance of about 80% was obs...

Photocatalytically visible light active thin SnO2/TiO2 bicomponent coatings with SnO2 underlayer, were deposited by spray pyrolysis. XRD, AFM, XPS and DRS analyses were used to characterize their morphology, phase and chemical composition, structure and band gap width. The model wastewater contaminant was diazo dye and the photocatalytic properties...

This work is focused on structural modification of phosphate materials by doping with transition metal oxides. The structure of (TiO2)x(V2O5)y(P2O5)100-x-y composites is discussed in terms of composition, structural units and valence variations. XRD diffraction, IR and XPS spectroscopic techniques are used to analyze the materials. The addition of...

Sol gel prepared nanocrystalline ZnO thin films are modified by combined usage of complexing agent (diethanolamine or monoethanolamine) and polymer (hydroxypropyl cellulose or ethylcellulose) in the initial sol. X-ray diffraction, Scanning electron microscopy and Atomic force microscopy are applied to get information about the crystallographic stru...

A two-step method has been applied to the synthesis of zinc orthostannate, Zn2SnO4. As a first step X-ray amorphous hydroxide precursor had been obtained by coprecipitation of Zn(NO3)2 and SnCl2 solutions using Na2CO3. In the second step the precursor was subjected to hydrothermal treatment (HT) in the presence of sodium hydroxide or ammonium hydro...

Interaction of a third harmonic of DPSS laser, wavelength 355 nm and pulse duration of 30 ns with titanium wafers was studied. It was investigated the structure of laser ablated titanium surface, depending on the laser beam scanning speed, and laser pulse frequency. The titanium surface modification was studied by scanning electron microscopy (SEM)...

The spray pyrolysis method has been applied to obtain cerium and chromium modified titania coatings. Wear resistance tests of the obtained samples have been carried out to compare the effects of Ce and Cr additives. The experimental runs of abrasive wearing of coatings were realised by means of the test rig TABER ABRASER according to the kinematica...

In this study ZnO photocatalysts were prepared by polymer-assisted precipitation, followed by hydrothermal treatment at 140 °C. The precursors were zinc acetate and a three-block copolymer. The obtained materials were char- acterized by X-ray diffraction (XRD), infrared spectroscopy (IRS) and BET analysis. The X-ray analysis and IRS proved the form...

Nanosized TiO2 films were deposited by spray pyrolysis and thermally treated at 400 o C. Then the films were dipped in 1M aqueous solution of HCl. The activated samples were divided into two parts – one part was dried (A) and another was annealed (AT) in air. The photocatalytic degradation of Reactive Black (RB5) textile dye under visible light was...

The crystallographicphase,surfacefeaturesandphotocatalyticpropertiesinthereaction of decolorizationofMalachiteGreendyeoverTiO2 (0–100mol%)dopedZnOfilmshave been investigated.Thefilmshavebeenpreparedbypolymermodifiedspraypyrolysis.The crystallization degreeandthesizeofthecrystallitescomprisingthefilmshavebeenfound to beinfluencedbytheTiO2 contentint...

Samples of Bulgarian perlite mineral deposit (natural alumino-silicate glass) in the Rhodope mountain were coated with Ag particles via a spray pyrolysis method. This method allows uniform distribution of the silver particles on the outer shell surfaces. SEM, XPS, FT-IR, and XRD methods were applied for characterization of the samples. The XRD inve...

Copper-doped ZnO nanoparticles have been prepared by the precipitation method. The dopant contents in the samples were 0.24, 0.35 and 1.07 at.%. A set of techniques including XRD, XPS, TG - DTA, EPR and BET analysis has been applied to characterize Cu-doped ZnO samples. The results showed that the crystallite sizes of ZnO and Cu-doped ZnO nanoparti...

The Bulgarian natural alumino-silicate glass (a deposit of "The Broken Mountain", municipality of Djebel) was coated with Cu nanoparticles via spray pyrolysis method. The formation of Cu-contained nanomaterial was proved by arc-AES, scanning electron microscope, XPS, IR and XRD methods. The developed by us methodology allows distribution of thin na...

Photocatalytically active ZnO nanosized films were deposited by polymer modified spray pyrolysis method. The influence of the polymers and the type of zinc precursor on the chemical composition, surface morphologies and the photocatalytic properties towards Malachite Green dye degradation were investigated. The amount of oxygen in the lattice (OL)...

Thin nano-sized TiO2 films were deposited on aluminum foil substrates by the spray pyrolysis method, using Ti(i-OPr)4 (TIP) and TiCl4 (TC) as precursors. The films were characterized by means of X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS). According to the XRD patterns the as-deposited film...

Nanocrystalline porous ZnO films are deposited onto alumina foil substrates by polyvinyl alcohol (PVA) modified spray pyrolysis. Water and ethanol–water mixture were used for preparation of the sols. The effect of polyvinyl alcohol on the morphological and photocatalytical properties of ZnO films was studied. It was found that the polyvinyl alcohol...

Thin nanocrystalline TiO2–SnO2 films (0–50 mol% SnO2) were prepared on quartz and stainless steel substrates by sol–gel coating method. The obtained films were investigated by XRD, Raman spectroscopy and XPS. The size of the nanocrystallites was determined by XRD–LB measurements. We ascertained that the increase of treatment temperature and concent...

Nanocrystalline porous ZnO films are deposited onto alumina foil substrates by polyvinyl alcohol (PVA) modified spray pyrolysis. Water and ethanol–water mixture were used for preparation of the sols. The effect of polyvinyl alcohol on the morphological and photocatalytical properties of ZnO films was studied. It was found that the polyvinyl alcohol...

Spray pyrolysis procedure for preparation of nanostructured TiO2 films with higher photocatalytic effectiveness and longer exploitation life is presented in this study. Thin films of active nanocrystalline TiO2 were obtained from titanium isopropoxide, stabilized with acetyl acetone and characterized by X-ray photoelectron spectroscopy (XPS), scann...

Thin nanocrystalline TiO2–SnO2 films (0–50 mol% SnO2) were prepared on quartz and stainless steel substrates by sol–gel coating method. The obtained films were investigated by XRD, Raman spectroscopy and XPS. The size of the nanocrystallites was determined by XRD–LB measurements. We ascertained that the increase of treatment temperature and concent...

Thin nano-sized TiO2 films were deposited on aluminum foil substrates by the spray pyrolysis method, using Ti(i-OPr)4 (TIP) and TiCl4 (TC) as precursors. The films were characterized by means of X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS). According to the XRD patterns the as-deposited film...

Bulgarian natural clinoptilolite was coated with copper and its oxides via spray pyrolysis method. D.C. arc-AES method revealed the presence of copper atoms. XRD patterns showed that after loading the Heulandite-type (HEU- type) structure is preserved. It is also proved that several copper phases exist on the zeolite: Cu, CuO and Cu 2O. The chemica...

Silver loaded zeolite was obtained by the spray pyrolysis method. The material was characterized by DC arc atomic emission spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), IR spectroscopy and scanning electron microscopy (SEM). The concentration of Ag in the final samples, calculated from the XPS spectra, corresp...

Photocatalytically active TiO 2 fi lms were successfully prepared by sol gel method. The solutions as well as suspensions enriched with Degussa P25 powder were spin coated on glass substrates. The phase composition and crystallite size of the fi lms were characterized by means of X-ray dif-fraction (XRD). The morphology and chemical composition wer...

Thin photocatalytically active TiO 2 fi lms are successfully deposited on glass and alumina foil substrates by spray pyrolysis method. The fi lms are characterized by means of X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), Thermal Analyses (TG-DTA). The XRD spectra of TiO 2 thin fi lms, treated...

Thin photocatalytically active TiO2 fi lms are successfully deposited on glass and alumina foil substrates by spray pyrolysis method. The films are characterized by means of X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), Thermal Analyses (TG-DTA). The XRD spectra of TiO2 thin fi lms, treated at...

Photocatalytically active TiO2 fi lms were successfully prepared by sol gel method. The solutions as well as suspensions enriched with Degussa P25 powder were spin coated on glass substrates. The phase composition and crystallite size of the fi lms were characterized by means of X-ray diffraction (XRD). The morphology and chemical composition were...

A clinoptilolite zeolite was coated with copper via ion exchange and spray pyrolysis methods. Cu-clinoptilolites were tested as catalysts for decomposition of gas phase ozone. Catalytic activity up to 90% ozone conversion was observed for samples loaded via spray pyrolysis and at the same time the catalysts remained active over time. Ion exchanged...

The Bulgarian natural alumino-silicate glass (A deposit of "The Broken Mountain" near the village of Vodenicharsko, municipality of Djebel) perlite was coated with Ag via the Spray pyrolysis method. Direct current arc Atomic Emission Spectroscopy (DC arc-AES), Scanning Electron Microscopy (SEM), X-ray photoelectron Spectroscopy (XPS), Infrared Spec...

Nanocrystalline porous ZnO films are deposited onto alumina foil substrates by polymer-modified spray pyrolysis of zinc nitrate and zinc acetate solutions. The dependence of the concentration of added ethylcellulose and the type of zinc precursor on both the photocatalytic properties and films morphologies is investigated. It is established that th...

Thin nanocrystalline TiO2–SnO2 films (0–50 mol% SnO2) are coated on quartz and stainless steel substrates by spray pyrolysis method. The synthesized films are investigated by XRD, Raman spectroscopy and XPS.The diffraction peaks of anatase phase fade while the peaks of rutile phase appear in the X-ray profiles with increasing of the treatment tempe...

TiO2 layers for gas sensing applications were obtained by Liquid Phase Deposition (LPD). The layers were deposited on gold-coated piezoelectric quartz crystals. The surface structure, morphology and chemical properties were analysed by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS). SEM showed...

The use of lasers in materials processing is an increasingly attractive choice for high technology manufacturing. Factors influencing the laser ablation process include laser beam parameters, such as wavelength, energy or fluence and pulse length, the material properties of the target, such as melting temperature, thermal diffusion rate, optical re...

The process of laser ablation of an aluminum surface with copper bromide laser (511 nm) was investigated by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), with the laser fluence varying from 5.3 to 11.1 J/cm2 and the laser beam scanning velocity from 20 to 100 mm/s. The experiments were done in two kinds of ambient a...