A key task nowadays is the development of novel materials and the enhancement of known ones in order to design high-performance anodes for sodium-ion batteries. This article presents a one-pot method of preparing a nanocomposite with hierarchical structure based on sodium trititanate and iron(III) oxide. In this method, simultaneous hydrothermal treatment of TiO2 and FeCl3 in a concentrated NaOH solution results in the formation of microscale particles self-assembled of Na2Ti3O7 nanotubes and Fe2O3 nanospheres. A Na2Ti3O7-Fe2O3 nanocomposite is being investigated for the first time as a potential anode material for sodium-ion batteries. It was found that combining Na2Ti3O7 with Fe2O3 as a high-capacitive modifier within the hierarchical structure improves Na-ion storage performance. Its specific capacity reaches about 220 and 50 mAh g-1 at 0.1C and 4 & Scy;, respectively. The pure Na2Ti3O7 gives only around 145 and 10 mAh g-1 at the same current densities. Besides, the Na2Ti3O7-Fe2O3 nanocomposite operates stably during 1000 charge/discharge cycles at a rate of 2C with a reversible capacity of 90 mAh g-1, whereas both pure Na2Ti3O7 and Fe2O3 exhibit worse long-term performance. These findings improve our knowledge of how to combine different materials in order to enhance their functionalities for application as an anode in sodium-ion batteries.

This article discusses potential solutions to overcome current limitations for clinical implementation of Mg implants by forming the biocompatible hybrid PEO-based inhibitor- and polymer-containing coatings for a controlled corrosion degradation of the bioresorbable material. Multifunctional hybrid coatings were obtained on MA8 magnesium alloy. The porous ceramic-like coating synthesized by plasma electrolytic oxidation served as a base for further modification with bioresorbable polymer (polycaprolactone, PCL) contained halloysite nanotubes (HNTs) with corrosion inhibitor (benzotriazole, BTA). The method for HNT impregnating with BTA and introducing them into the matrix of PCL was proposed. The chemical composition of the protective layers was studied using SEM-EDX, XRD, XPS, and Raman microspectroscopy. Anticorrosion protection level of the coated specimens was determined by means of electrochemical techniques, weight loss, and hydrogen evolution tests. The samples with hybrid layers showed the best corrosion protection during 23 h exposure to Hanks' Balanced Salt Solution ( |Z|f = 0.1 Hz = 1.02 M Qcm2 , IC = 11 nA cm-2 , Rp = 2.4 M Qcm2 ) and the lowest degradation rate (0.021 mm/year) after 7 day of exposure to HBSS among all the tested samples. The electrochemical activity on microscale of samples with the studied coatings was estimated by localized electrochemical techniques. The degradation mechanism of specimens with hybrid layers was proposed. The prospects of hybrid layer application in regulating the resorption process of Mg alloys were shown. (c) 2025 Chongqing University. Publishing services provided by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )

The LaMnO3/TiO2/Ti composite active in the oxidation of CO into CO2 at 300-400 degrees C was formed by plasma electrolytic oxidation (PEO) in silicate electrolyte containing dispersed lanthanum manganite (LMO) nanoparticles (NPs). In PEO process, inert and reactive mechanisms of LMO NPs incorporation are realized, which leads to the formation of a 33 +/- 4 mu m thick coating consisting of TiO2 (rutile), LaMnO3 and La7 & sdot;58(Si1 & sdot;048O4)6O2. Both individual NPs and their micro-sized agglomerates, tightly fixed in the TiO2 layer, were found on the melted areas of the coating surface. In addition, the particle agglomerates fill open pores on the surface and cavities in the bulk of the coating, including those near the coating/titanium interface. According to XPS data, the surface layer contains 1.2 at% La3+ and 1.7 at% (Mn3++Mn4+). After catalysis, the total concentrations of lanthanum and manganese are preserved, but the percentage of more oxidized manganese Mn4+ increases. The relatively low catalytic activity of the LaMnO3/TiO2/Ti composite may be due to its low specific surface area, the stoichiometry of the embedded LMO NPs, their interaction with the coating material, and the low concentration of manganese in the outer layer.

The advancement of sodium-ion batteries (SIBs) depends on designing high-performance anode materials. Hard carbon (HC) is a suitable candidate due to the availability and low cost of resources for production, but its limited reversible capacity and unsafeness upon high-rate charging remain obstacles. Herein, a novel simple strategy combining low-temperature pyrolysis and hydrothermal treatment for the fabrication of a synergistic composite based on hard carbon coated by molybdenum disulfide nanosheets has been developed. The MoS2@HC composite shows superior electrochemical characteristics for SIBs in contrast with HC and MoS2 on their own. In particular, it demonstrates almost two times better sodium storage ability at high current densities as compared to HC. The operating potential of the MoS2@HC composite is higher than that of HC, implying improved battery safety. At the same time, the composite shows a better cycle life than MoS2. It stays stable during long-term cycling, whereas MoS2 shows unacceptable behavior already after the 100th cycle. The resulting MoS2@HC composite at low current density of 20 mA g–1 delivers a reversible capacity stabilized at 304 mAh g–1. It also demonstrates cycling stability at high current densities with a capacity of 131 mAh g–1 over 200 cycles at 1000 mA g–1. This research opens a facile way for designing hard carbon based anode for sodium-ion batteries with increased capacity and improved safety.

Na2Ti3O7 has attracted attention as an alternative to hard carbon anode for Na-ion batteries due to suitable sodiation potential and, hence, no serious safety issues at high current densities. However, unfavorable electronic transport properties of Na2Ti3O7 need to be addressed to make it applicable for practice. Herein, a hydrothermal method was adopted to fabricate Na2Ti3O7 having a hierarchical micro/nano architecture and to dope it with copper through one stage. As compared to the non-doped Na2Ti3O7, the copper-containing product shows increased electronic conductivity (2.5 times higher) due to a smaller band gap (reduced by similar to 1 eV). Because of Cu-doping, the Na2Ti3O7 crystal structure has evolved, and its unit cell volume has increased by about 9.5 %. Doping with Cu enhances the electrochemical performance of Na2Ti3O7 in Na-ion batteries, which demonstrates higher rate capability (2.0-2.5 times more capacity at high current densities) and remarkable cycleability (85 % capacity retention over 300 cycles at 2C). The calculations show that Cu-doped Na2Ti3O7 is characterized by improved Na+ ion diffusion and increased contribution of the pseudocapacitive current during the sodiation-desodiation process. The research discloses the aspects of copper-doping strategy that enable to unfold the capability of Na2Ti3O7 for energy storage applications.

The present study investigates the physical and chemical characteristics, behavior in vitro and in vivo, and biocompatibility of coatings containing Ta2O5, which are obtained by plasma electrolytic oxidation (PEO) on MA8 magnesium alloy. The obtained coatings demonstrate in vivo biocompatibility and in vitro bioactivity. Compared to the base PEO coating, the layers containing Ta2O5 facilitate the development of apatite in simulated body fluid, suggesting that the inclusion of nanoparticles improves bioactivity of the coatings. It was found that incorporation of Ta2O5 nanoparticles increases roughness and porosity of the formed layers by increasing particle concentration in electrolytes for the PEO process contributing to sufficient soft tissue ingrowth in vivo. Based on in vivo studies, these coatings also provide favorable tissue response and minimal inflammatory reaction in comparison with the bare magnesium alloy due to protection of living tissues from deleterious corrosion events of magnesium implant such as local alkalization and intense hydrogen evolution. The results obtained in the present study concluded biocompatibility, tissue integration of the PEO coatings containing Ta2O5 nanoparticles making them a promising protective layer for biodegradable magnesium implants.

The efficiency of the green inhibitors (sodium salts of fumarate, glycolate and gluconate) in suppressing corrosion of the structural MA8 magnesium alloy (MgMnCe) and the biomedical Mg0.8Ca alloy was studied using the hydrogen evolution measurements, mass loss test, EIS, PDP, SVET/SIET. The analysis of the morphology, chemical composition, and growth kinetic of corrosion films formed in 0.9 wt% NaCl solution with and without corrosion inhibitors was carried out. The most compact surface film with the smallest thickness was formed in a saline solution with sodium fumarate. The Mg alloy samples exhibited the highest polarization resistance, the lowest localized electrochemical activity, and the lowest corrosion rate in saline with the addition of sodium fumarate and sodium glycolate. The efficiency of the applied inhibitors was up to 81 %. The model of the corrosion mechanism based on the sorption of molecules of organic inhibitors is proposed. The results show the high compatibility of the used inhibitors with the calcium-phosphate PEO-matrix, indicating the possibility of forming a self-healing coating by means of these active substances.

Catalytically active coatings on titanium were formed by plasma electrolytic oxidation (PEO) in the aqueous electrolytes containing Na6P6O18, NaVO3, and/or Na2MoO4. The coatings were investigated by EDS, XPS, and SEM methods. The results show that the replacement of NaVO3 by Na2MoO4 in the electrolyte leads to the substitution of V for Ti in the coatings and the concentrating Mo in the surface layers. In turn, this causes a smoothing of the surface relief, a change in the shape of large pores from oval to round, and a decrease in surface porosity. As to XPS, partially reduced Mo4+ (or Mo5+) and V4+, along with Mo6+, V5+, are present in the surface part of the coatings, facilitating the formation of catalytically active sites on the specimen surfaces. Screening shows that all PEO-coated specimens catalyze the reactions of oxidative denitrogenation (ODN) and oxidative desulfurization (ODS) using hydrogen peroxide as the oxidizing agent. Tendencies were found for a decrease in the conversion of dibezothiophene in 4 h with an increase in the Ti + Mo concentration and for a decrease in the conversion of thiophene, methylphenyl sulfide and pyridine with a decrease in the concentration of Ti + V + Mo. The regularities of simultaneous oxidation of thiophene and pyridine in their mixture were determined for Vcontaining catalysts and for Mo-containing ones. It was found that V-containing PEO composite accelerates both ODS and ODN reactions, while Mo-containing one accelerates the ODN reaction and slows down the ODS reaction.

V-, W-containing oxide-phosphate layers on titanium were obtained by plasma electrolytic oxidation (PEO) for 5 min at anode current density i = 0.08 A/cm2 in electrolytes containing 0.05 mol/L Na6P6O18 and 0.1 mol/L (Na2WO4 + NaVO3). The effect of replacing vanadate with tungstate (NaVO3:Na2WO4 = 0:1, 1:3, 1:1, 3:1, and 1:0) was studied on voltage-time responses, PEO coatings surface morphology, composition, optical and pho-tocatalytic properties. The coatings were investigated by X-ray diffraction analysis, scanning electron micro-scopy, energy-dispersive X-ray microanalysis, X-ray photoelectron spectroscopy, and diffuse reflectance spectroscopy. Under experimental conditions, amorphous coatings with a thickness of 18-27 mu m and a surface porosity of 1.5-3.6% were formed. Results show that vanadium (up to 10.5 at. %) and tungsten (up to 5.2 at. %) are incorporated into surface layers in proportion to their concentrations in electrolyte. The main mechanism for the incorporation of V and W into coatings is assumed to be thermolysis of vanadungstophosphate hetero-polyoxoanions, while high concentrations of polyphosphate species contribute to the amorphization of coatings and the formation of a titanium phosphate matrix. The band gap of V-containing composites decreases from 2.22 to 1.97 eV as tungsten replaces vanadium. For W-containing composites (V-free ones), the band gap is 3.19 eV. All formed coatings exhibit photocatalytic activity in the degradation of methyl orange (10 mg/L MO, 10 mmol/L H2O2) in a neutral medium (pH 6.8) under visible and UV irradiation. The gradual substitution of vanadium for tungsten in the coatings leads to a decrease in MO degradation (from 87 to 50% and from 32 to 9% under 3-h UV and visible irradiation) with a simultaneous increase in their durability due to a decrease in vanadium leaching. An electrolyte with Na2WO4:NaVO3 = 1:3 is optimal for the formation of photoactive and stable composites. When using composites obtained in this electrolyte, MO conversions are 83 and 31% under UV and visible irradiation, respectively. The mechanism of the photocatalytic action of WO3-V2O5-TiO2 composites is consid-ered, and the role of hydrogen peroxide is discussed.

A -0.8-0.9 & mu;m thick Mg2Si film was grown by pulsed deposition of Mg on Si(111) at 340 degrees C in UHV. The X-Ray Diffraction (XRD) and cross-sectional High-resolution Transmission Electron Microscopy (x-HRTEM) data demonstrate the high crystal quality and nearly 100% texture of the film. Energy Dispersive X-ray spectroscopy (EDX) and X-ray Photoelectron Spectroscopy (XPS) depth profiling show that the synthesized Mg2Si contains some oxygen. Hall measurements reveal the p-type conductivity of 130 S/cm and carrier concentration of 6 x 1018 cm-3 at room temperature (RT), the acceptor concentration of -1.4 x 1018 cm-3 at 190 K, hole activation energy Ea & AP;26 meV, mobility & mu;-5050 cm2/V & BULL;s at 75 K and & mu;-134 cm2/V & BULL;s at RT. The p-type conductivity is related to either unintentional doping with oxygen or/and Mg vacancies occurred during the non-equilibrium process of silicide ultra-fast formation. The outstanding transport parameters of the film are explained by its high crystal quality and texture. The films with such thickness and transport properties are suitable for photo-voltaic and thermoelectric applications.

The high corrosion rate of magnesium and its alloys in chloride-containing solution significantly reduces the potential of this material for diverse applications. Therefore, the formation of a smart protective coating was achieved in this work to prevent degradation of the MA8 magnesium alloy. A porous ceramic-like matrix was obtained on the material by plasma electrolytic oxidation (PEO). Further surface functionalization was performed using layered double hydroxides (LDH) served as nanocontainers for the corrosion inhibitor. Several methods of LDH intercalation with benzotriazole (BTA) were proposed. The composition and morphology of the formed coating were studied using SEM-EDX analysis, XRD, XPS, and Raman microspectroscopy. The corrosion behavior of the coated samples was evaluated using electrochemical impedance spectroscopy and potentiodynamic polarization. The corrosion rate was estimated using volumetry and gravimetry methods. The formed composite coating provides the Mg alloy with the lowest corrosion activity (|Z|f = 0.1 Hz = 8.48·105 Ω·cm2, Ic = 1.4·10−8 A/cm2, PH = 0.21 mm/year) and improves the protective properties of the PEO-coated sample (|Z|f = 0.1 Hz = 8.37·103 Ω·cm2, Ic = 4.1·10−7 A/cm2, PH = 0.31 mm/year). The realization of the self-healing effect of the inhibitor-containing LDH/PEO-coated system was studied using localized electrochemical methods (SVET and SIET) with two artificial defects on the surface. A mechanism involving three stages for the active corrosion protection of the alloy was proposed. These findings contribute to the follow-up work of developing modified LDH/PEO-based structures that promote the Mg alloy with high corrosion resistance, superior electrochemical performance for applications in various fields of industry and medicine.

The protective coating with a self-organized microtubular structure was formed using plasma electrolytic oxidation (PEO) on AlMg3 aluminum alloy in the tartrate-fluoride electrolyte. This protective layer was further modified using corrosion inhibitors of the azole group (1,2,4-triazole, benzotriazole) and polymer material (polyvinilidene fluoride, PVDF). X-ray diffraction analysis and scanning electron microscopy with energy dispersive spectroscopy were used to study the morphology and composition of the obtained oxide coatings. The presence of the inhibitor in the PEO-layer was confirmed using micro-Raman spectroscopy and X-ray photoelectron spectroscopy. The level of corrosion protection of formed coatings as well as the effect of loaded inhibitors on the anticorrosion efficiency was evaluated using electrochemical impedance spectroscopy (EIS) and localized scanning techniques (SVET/SIET). The coating impregnation with corrosion inhibitors of the azole group significantly improves the corrosion characteristics of the material. Impregnation of the base PEO-layer with 1,2,4-triazole during 24 h results in a 36 times increase in the impedance modulus measured at the lowest frequency (|Z|f=0.1Hz). Additional sealing of impregnated coating with polymer improves the corrosion stability of the treated material. On the base of the obtained data, the optimal way of protective inhibitor- and polymer-containing formation using surface treatment was suggested. The best barrier properties were established for hybrid coatings obtained by the immersion of a PEO-coated sample in 1,2,4-triazole solution for 24 h and following spraying the PVDF solution. The value of |Z|f=0.1Hz for this protective layer increased by more than two orders of magnitude in comparison with the base PEO-layer. The three-stage mechanism of corrosion inhibition of the sample with smart inhibitor-containing coating was established.

A novel approach to surface modification was developed to improve the corrosion performance of biodegradable magnesium alloys. Additively manufactured magnesium samples and Mg-Mn-based magnesium alloys were used in this study. This method involves the combination of plasma electrolytic oxidation to create a porous ceramic-like matrix, followed by treatment with protective biocompatible agents. The most efficient method for the PEO-layer impregnation using sodium oleate and polycaprolactone was selected and optimized. The correlation between the structure, composition, and protective properties of the hybrid coatings was established. The composition of the formed polymer-containing layers was established using XPS and Raman microspectroscopy. The presence of sodium oleate and its distribution across the coating surface was confirmed at the microscale. The corrosion-protection level of the hybrid layers was assessed using potentiodynamic polarization measurements, electrochemical impedance spectroscopy, hydrogen evolution testing, and gravimetry (mass-loss tests) in vitro. The oleate-containing polycaprolactone layers (HC-SO 0.1–2) demonstrated stable corrosion behavior even after 7 days of immersion in Hank’s balanced salt solution. The corrosion-current density and impedance modulus measured at a frequency of 0.1 Hz for the samples with hybrid coating after 7 days of exposure were equal to 5.68 × 10−8 A∙cm−2 and 2.03 × 106 Ω∙cm2, respectively. The developed method of surface modification demonstrates the coating’s self-healing properties. The effectiveness of employing hybrid anticorrosive bioactive PEO coatings for biomedical products made from magnesium and its alloys was demonstrated.

The method of hybrid coating formation on the surface of a bioresorbable wrought magnesium alloy and magnesium obtained by additive technology was proposed. Plasma electrolytic oxidation (PEO) with subsequent treatment of the material using an organic biocompatible corrosion inhibitor and a bioresorbable polymer material was used to obtain the protective layers. The optimal method of surface treatment was suggested. Using SEM/EDX analysis, XRD, XPS, and confocal Raman microspectroscopy, the composition of the formed surface layers was determined. The corrosion protection performance of the formed coatings was studied by potentiodynamic polarization and electrochemical impedance spectroscopy techniques in 0.9 wt.% NaCl and HBSS. Hydrogen evolution and mass loss tests were performed to study the corrosion rate of samples with different types of protective coatings. Sealing the pores of PEO coating with a polymeric material contributes to a significant reduction in the amount of the inhibitor diffusing into a corrosive medium. The best barrier properties were established for the hybrid coating formed with a one-stage application of benzotriazole and polycaprolactone. Such layers reduce the rate of alloy degradation due to active protection.

The work provides the results of the one-step formation of boron-containing coatings on an Mg–Mn–Ce alloy by plasma electrolytic oxidation. The results of studies of the composition, structure and morphology of heteroxide coatings are presented. It was established that the boron is contained in the coating mainly in the form of B or B2O3. The introduction of B changes the color of coatings, and also helps to increase their porosity. The method of determining the full cross section of the interaction of thermal neutron absorption efficiency by samples material using the installation of neutron-activation analysis based on 252Cf was developed. It was shown that the introduction of boron into the formed coatings allows to increase the macroscopic cross-section of the interaction of samples with thermal neutrons by 3.8 times. This effect opens the potential for the use of synthesized material in the field of nuclear technologies and aerospace industry.

FexCo1−xWO4 films on the titanium were formed by one-step plasma electrolytic oxidation in tungstate electrolytes containing Fe(II)-EDTA and/or Co(II)-EDTA anions. The resulting composites were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS), diffuse reflection, and electrochemical impedance spectroscopy (EIS). All formed coatings contain TiO2 in the anatase modification and orthorhombic WO3. The oxide layers obtained in a tungstate electrolyte with the addition of only Co(II)-EDTA ions also include CoWO4. Based on Mott–Schottky plots all samples show a positive slope, indicating the behavior of an n-type semiconductor. For the composites obtained, the values of the band gap determined by the Tauc method for direct allowed transitions are 2.5–2.9 eV. The resulting composites exhibit photocatalytic activity in the degradation of methyl orange (10 mg/L, pH 6.8, С(Н2О2) = 10 mmol/L) under UV and visible light irradiation. The highest MO degradation reaches 80

Titanium-supported TiO2-WO3-Eu2(WO4)3 film heterostructures have been formed by combining two methods -plasma electrolytic oxidation (PEO) of titanium in acidic tungstate solution and extraction pyrolytic (EP) deposition of europium organic extract paste. As a result of annealing of the composites at 700 and 800 degrees C for 2 h, Eu2(WO4)3 and WO3 crystallize in their composition, while anatase from PEO coating transforms into rutile. WO3 microcrystals and elongated chains of molten formations attributed to Eu2(WO4)3 are visible on SEM images of the composite surfaces. XPS confirms the presence of Eu3+, W6+, W5+, and W4+in the subsurface layers of the composites. The luminescence properties of the resulting composites were evaluated from the luminescence excitation spectra and luminescence spectra at 300 K. All composites exhibit luminescence in the red region with a maximum at lambda max approximate to 620 nm (lambda ex= 250 nm). All formed coatings exhibited photocatalytic activity in the reaction of degradation of indigo carmine (IC, 10 mg/L, pH 4.6) under UV irradiation.(c) 2023 Elsevier B.V. All rights reserved.

Herein, a method for the preparation of hard carbon via carbonization of chemically modified (molybdenum-doped) commercially available viscose fiber was developed. The effects of a molybdenum dopant on carbonization conditions were studied. The carbonization products retained the fibrous structure and flexibility. The structural features of the synthesized hard carbon materials were investigated, and their relationships to the carbonization temperature and the amount of the molybdenum dopant were analyzed. The texture of materials was studied, and correlations between the specific surface area and porosity, on the one hand, and the synthesis conditions, on the other, were discovered. The usefulness of the products as anode materials for sodium-ion batteries was evaluated. The electrochemical tests, together the extant relevant data, indicate that molybdenum induces the structural rearrangement of the carbon framework upon annealing, accompanied by the growth and ordering of graphite-like nanoclusters. The material prepared at 1050°C exhibited the best electrochemical performances among the synthesized products and the stable cyclability with a capacity of 290 (mA h)/g at a current density of 25 mA/g.

A comprehensive study of the properties of coatings formed on a magnesium alloy by plasma electrolytic oxidation (PEO) using the electrolytes with nanosized particles of anatase (titanium dioxide) has been carried out. Formed coatings reduce corrosion current density 2.5-fold and increase hardness by 25% compared to a coating without particles. Confocal micro-Raman spectroscopy revealed the presence of anatase and rutile phases in the composition of PEO coating due to the incorporation of TiO2 nanoparticles during plasma electrolytic treatment. The presence of titanium dioxide had a positive effect on the photocatalytic properties of coatings: the constant rate of the methyl orange and methyl blue decomposition is increased in 1.6 and 1.8-fold, respectively, compared to the coating formed in electrolyte without TiO2 particles.

Ti/TiO2-Sb-SbOx multifunctional sensors were obtained by plasma electrolytic oxidation in the anodic–cathodic mode. The resulting films contain TiO2 and up to 5 at.