Search Results (568)

Focused-ion-beam scanning electron microscopy (FIB-SEM) provides site-specific access to buried interfaces, particle interiors, porous electrode architectures, and localized degradation regions in energy materials. This capability is particularly valuable for rechargeable batteries, solid-state ion conductors, alkali-metal electrodes, and reactive solid–liquid interfaces, where the structures governing transport and failure are rarely exposed at a free surface. However, the preparation and imaging steps that reveal these regions may also alter them. Ion milling, environmental transfer, vacuum exposure, scanning electron microscopy (SEM), cryogenic handling, transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDS), electron energy-loss spectroscopy (EELS), and atom probe tomography (APT) can each modify local morphology, chemistry, or phase state. These effects are especially important when the intended evidence involves light elements, metastable phases, nanoscale coatings, reactive interphases, volatile species, or ion-conducting materials. This perspective develops a claim-specific framework for evaluating such results. Preparation- and imaging-induced changes are related to the material feature being interpreted and to the minimum control needed to distinguish the two origins. For porous electrodes, the relevant outputs include pore volume, connectivity, tortuosity, crack geometry, phase fraction, and active surface area. For reactive interfaces and solid electrolytes, the critical questions concern alkali-metal redistribution, surface amorphization, light-element contrast, implanted-species chemistry, and beam-induced phase formation. The discussion further compares conventional Ga-FIB, cryogenic FIB, Xe plasma FIB, low-energy Ar+ polishing, broad-ion-beam preparation, ultramicrotomy, and repeated particle-oriented FIB workflows. Reliable interpretation requires the preparation route, transfer conditions, imaging dose, analytical acquisition, and claim-specific controls to be reported together with the final microscopy result. Full article

Inorganic mercury ions (Hg²⁺) are highly toxic, posing a threat to aquatic ecosystems and human health. In this study, iron phthalocyanine (FePc) was anchored onto the surface of MXene via a self-assembly strategy to construct an FePc/MXene-x (F/M-x) heterostructure. Characterization by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption–desorption (BET) confirmed that the high specific surface area and good conductivity of MXene effectively inhibited FePc aggregation and increased the exposure of active sites. The F/M-x composite was then modified onto a glassy carbon electrode (GCE) to fabricate an electrochemical sensor, and the detection performance for Hg²⁺ was evaluated using square-wave anodic stripping voltammetry (SWASV). Under optimized conditions (pH = 5.0, accumulation at −1.2 V for 180 s), the F/M-100/GCE exhibited a linear range of 0.1–1.0 μM, a sensitivity of 19.02 μA/μM, and a detection limit of 5.9 nM. The sensor showed good anti-interference ability against coexisting metal ions such as Cd²⁺, Cu²⁺, and Pb²⁺, with a batch-to-batch RSD of 2.03% and a long-term stability RSD of 2.49%. Spike recovery experiments in real water samples (lake water and groundwater) verified the accuracy of the method. This study provides a new electrochemical platform for the rapid detection of trace Hg²⁺ in water environments. Full article

For the removal of hexavalent chromium [Cr(VI)] from drinking water, a hybrid biosorbent designated chitosan–natural diatomaceous earth (CNDE) was developed and thoroughly characterized. The material couples the ion-exchange and chelating capacity of chitosan—applied at an 85% degree of deacetylation—with the high-surface-area mineral framework of natural diatomaceous earth, onto which the polymer was deposited as a conformal coating. Surface morphology and internal microstructure were examined by scanning and transmission electron microscopy (SEM/TEM), while elemental composition across the hybrid matrix was resolved by energy-dispersive X-ray spectroscopy (EDX). Fourier transform infrared (FTIR) spectroscopy was employed to identify the surface functional groups responsible for chromate binding, and streaming current measurements established the pH of zero charge (pH_pzc), which governs the electrostatic environment at the sorbent–solution interface. Specific surface area was quantified by the Brunauer–Emmett–Teller (BET) method, and the balance of surface acidic and basic sites was determined through titrimetric analysis of total acidity and alkalinity. Thermogravimetric analysis (TGA) was conducted to assess thermal stability. Batch equilibrium isotherm experiments were performed to evaluate Cr(VI) uptake from model drinking water prepared using dilute potassium dichromate solutions adjusted to target pH levels. The effects of solution pH and competing anions (chloride and sulfate) were also investigated. Kinetic studies were conducted to determine the rate of Cr(VI) adsorption, and residual metal concentrations were measured using inductively coupled plasma mass spectrometry (ICP-MS). Results indicated that CNDE containing 30% chitosan (CNDE30) achieved effective Cr(VI) removal at pH 5. Adsorption was strongly pH-dependent, decreasing as pH increased from 5 to 8. Equilibrium data were well described by both Langmuir and Freundlich isotherm models, while kinetic data followed a pseudo-second-order model. The presence of chloride ions (15 mg/L) reduced adsorption capacity by approximately one-third, whereas sulfate at the same concentration significantly inhibited Cr(VI) removal. Overall, the isotherm results suggest that CNDE30 is a promising material for Cr(VI) removal from drinking water. Its cost-effectiveness, ease of synthesis, and potential for reuse make it particularly attractive for small-scale and decentralized water treatment applications. Full article

This review examines recent advances in multifunctional probes that integrate optical and electrochemical channels for in vitro/in vivo studies. Integration of electrodes with optical fibers provides a powerful platform for localized light delivery and simultaneous electrochemical detection of cellular metabolites both within and at the surface of single living cells. These hybrid devices bridge optical stimulation methods, including optogenetics, and electrochemical monitoring of the cellular response within the same experimental preparation. The review systematically categorizes distinct probe architectures: optical nanoendoscopes for intracellular measurements, probes with a shared opto-electrochemical channel, devices where optical and electrochemical channels are physically separated, and probes engineered for neural interfaces and scanning probe microscopy. For each category, fabrication approaches, surface modification strategies, and representative biological applications are discussed. Particular attention is given to the fundamental tension between optical transparency and electrical conductivity in shared-channel designs, to the mechanical requirements imposed by neural tissue on implantable probes, and to the spatial resolution limits of current scanning probe platforms. The review concludes with a critical assessment of current limitations and future directions, including higher spatial resolution, simultaneous multiplexed analyte detection and broader translation of these technologies toward in vivo experimental models. Full article

The pervasive issue of lead contamination in water systems necessitates the development of advanced and sustainable remediation methodologies. Powdered activated carbon synthesized from Pinus roxburghii has been meticulously evaluated as a high-performance capture medium to remove sequestration of lead ions from aqueous systems through batch adsorption studies. These adsorption dynamics were optimized by Response Surface Methodology integrated with Central Composite Design, enabling precise calibration of crucial influential factors such as pH, contact time, and adsorbent dosage. Morphological analysis conducted using Scanning Electron Microscopy confirmed a highly porous structure, while Fourier Transform Infrared Spectroscopy identified functional groups, such as hydroxyl groups coupled with carbonyl groups, which exhibit strong metal affinity. Under optimal conditions, a pH of 8.2, a time of 140 min, and an adsorbent dosage of 0.03 g/L resulted in a maximum lead removal efficiency of 99.86%. Validation trials substantiated the reproducibility of the process, yielding a marginally diminished efficiency of 98.62 ± 1.24%. The integration of RSM not only validated the statistical significance of the experimental outcomes but also reinforced the predictive accuracy. This study demonstrates the critical interplay of adsorption parameters and highlights the physicochemical properties of Pinus roxburghii-based activated carbon, emphasizing its potential for advanced water purification processes. Full article

The purpose of this study was to examine the utilization of 0–45 μm aluminum hydrate fraction (gibbsite) manufactured by Alum SA Tulcea, as a precursor in the hydrothermal synthesis process of nanosize boehmite from gibbsite suspensions. Furthermore, the use of the produced material as adsorbent of lanthanum (III) ions was investigated using aqueous solutions. Thermogravimetric analysis (TG), Fourier Transform InfraRed Spectroscopy (FT-IR), Wide-Angle X-Ray Scattering (WAXS), and atomic force microscopy (AFM) were used to demonstrate the preparation of the required material. Additionally, the material point of zero charge (pHpzc) and material specific surface (using BET approach) were evaluated. By conducting adsorption studies, the specific parameters for the lanthanum adsorption process were evaluated. The effects of pH, the ratio of adsorbent material to La(III) quantity from aqueous solution, contact time, and La(III) initial concentration were also assessed. Based on the obtained experimental data, it was proved that the maximum adsorption capacity of 97.7 mg/g was obtained for a solid:liquid ratio = 0.1 g:25 mL, pH between 3 and 6, temperature of 298 K, and contact time of 90 min. The studied adsorption process is most effectively described by the Sips model, suggesting an intricate interaction among the adsorbent material and La (III) ions. The prepared adsorbent exhibited a good desorption capacity (higher than 93%) when 20% HCl was used for desorption. Full article

In this study, zinc-modified biochar (ZBC) was prepared from rose willow, and NiCoMn-LDHs@ZBC composites were synthesized using a hydrothermal method. The composites were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area analysis, scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The adsorption mechanism of As(V) from aqueous solution onto NiCoMn-LDHs@ZBC was investigated through a series of arsenic adsorption experiments. The effects of various experimental parameters (including adsorbent composition and ratio, adsorbent dosage, solution pH, contact time, temperature, and coexisting ions) on the adsorption capacity were evaluated. Additionally, adsorption model fitting and kinetic analysis were conducted. The results indicate that the adsorption process follows the pseudo-second-order kinetic model (linear correlation coefficient R² = 0.99), while the isothermal adsorption process adheres to the Langmuir model, with a maximum adsorption capacity of 159.780 mg/g. The adsorption process is primarily dominated by chemisorption and involves three pathways: first, electrostatic attraction between the material surface and arsenic-containing ions; second, ion exchange between arsenic-containing ions and interlayer carbonate ions; and third, coordination reactions between the surface hydroxyl groups (-OH) of NiCoMn-LDHs@ZBC and As, forming As-O-M inner-sphere complexes as adsorption proceeds. Furthermore, the NiCoMn-LDHs@ZBC composite exhibits relatively stable reusability, demonstrating significant potential for the treatment of arsenic pollution in water bodies. Full article

NASICON-type Na₃V₂(PO₄)₃ (NVP) is widely regarded as a promising cathode for sodium-ion batteries owing to its robust three-dimensional framework and high operating voltage (~3.4 V vs. Na⁺/Na). However, NVP suffers severe capacity degradation under fast-charging conditions due to its intrinsically low electronic conductivity, which critically impedes its practical deployment. Herein, we systematically investigate the fast-charging failure mechanism of NVP and propose a trace Sm³⁺ doping strategy (x = 0.03) to address this limitation. Undoped NVP retains only 13.5% and 56.62% of its initial capacity after 1000 cycles at 5000 mA g⁻¹ and 1307 cycles at 2000 mA g⁻¹, respectively. Post-cycling scanning electron microscopy (SEM) reveals extensive crack formation and particle pulverization, providing direct morphological evidence for structural failure. To overcome this, Sm³⁺-doped Na₃V_1.97Sm_0.03(PO₄)₃/C (NVPSM) is synthesized via a sol–gel method. X-ray diffraction (XRD) confirms that the NASICON phase is preserved. Raman spectroscopy reveals an improved graphitization degree (I_D/I_G = 0.97 vs. 1.02 for NVP), and X-ray photoelectron spectroscopy (XPS) verifies the V³⁺ oxidation state and the incorporation of Sm³⁺. Electrochemically, NVPSM achieves capacity retentions of 60.3% after 2300 cycles at 5000 mA g⁻¹ and 83.89% after 1436 cycles at 2000 mA g⁻¹. Electrochemical impedance spectroscopy confirms reduced charge-transfer resistance, and post-cycling SEM shows markedly improved structural integrity. These results demonstrate that trace rare-earth doping effectively mitigates fast-charging-induced structural failure in NVP-based cathodes. Full article

K-ion batteries (KIB) are considered the future energy storage and conversion technology due to their remarkable performance. In this work, a high-temperature solid-state process was used to effectively synthesize KMnO₂, a promising cathode material for KIBs. The materials were examined using X-ray powder diffraction (XRPD), Raman and infrared spectroscopies, electron microscopy analysis, optical, and impedance spectroscopies. Rietveld refinement of X-ray diffraction data confirmed that the compound crystallizes in the monoclinic system with the P-2₁/m space group. Fourier transform infrared and Raman spectroscopies revealed the vibrational modes of the KMnO₂ compound and proved the existence of the octahedral environment MO₆ (M = Mn, K), which affirms structural configuration. The morphological distribution and grain size of the titled compound were examined using SEM studies. A direct band gap of around 3.12 eV was found by optical studies using UV–Vis spectroscopy, confirming the semiconducting nature of KMnO₂ and indicating its applicability for optoelectronic and energy-related applications. The characteristics of this material were further examined using impedance spectroscopy at temperatures between 343 and 443 K and a frequency range of 10⁻¹ Hz to 10⁶ Hz. The DC conductivity and relaxation time exhibited Arrhenius behavior, with a significant shift in activation energy at 373 K, suggesting a change in the conduction mechanism. The frequency behavior of AC conductivity, σ_ac, was analyzed using the universal Jonscher law. The findings of the charge transportation study on KMnO₂ indicate that this material follows a non-overlapping small polaron tunneling (NSPT) for T < 383 K and correlated barrier hopping (CBH) above for T > 383 K. A correlation between the ionic conductivity and the crystal structure was established and discussed. Full article

To clarify the control mechanism of water quality parameters on metal particle release from pipe scales in aging ductile iron water supply pipelines (service life > 20 years), this study conducted single-factor experiments to explore the effects of pH, temperature, concentration of humic acid (HA) and Mn²⁺ on Fe, Mn, and Al particle release. Combined with inductively coupled plasma optical emission spectrometry (ICP-OES) for quantitative detection, first-order/second-order kinetic fitting, and X-ray diffraction (XRD) and scanning electron microscopy-energy dispersive spectrometry (SEM-EDS) characterization, the results showed that an increase in temperature generally promoted the aggregation and sedimentation of metal particles, among which Fe and Mn particles were more sensitive to temperature changes. pH affected the sedimentation process by controlling metal ion speciation and particle surface charge: low pH significantly accelerated pipe scale dissolution, while weakly alkaline conditions prolonged particle suspension time. Low-concentration HA (0.5 mg/L) promoted particle dissolution, whereas high-concentration HA (1.0–2.0 mg/L) extended particle retention time through surface coating. Mn²⁺ concentration exhibited an obvious concentration-dependent effect: the range of 20–50 μg/L enhanced particle suspension stability, while 80–100 μg/L accelerated particle aggregation and sedimentation. The pipe scales mainly consisted of Fe₃O₄, Fe₂O₃, Mn₃O₄, and Al₂O₃, with metal release regulated by the “element complexation–particle aggregation–crystal growth” pathway. Particle sedimentation followed first-order kinetics. Controlling pH at 7.0, temperature < 30 °C, and reducing HA/Mn²⁺ concentrations effectively weakened metal particle migration. This study reveals the coupled effect mechanism of water quality parameters, providing theoretical and technical support for optimizing water quality control and solving the “yellow water” problem. Full article

Sustainable valorization of biomass through hydrothermal carbonization (HTC) represents an environmentally benign method for producing carbon materials for water treatment applications. This research aims to optimize the production of hydrochar from waste food by focusing on parameter optimization, physicochemical characterization, and the capacity of hydrochar to act as an adsorbent for the removal of the copper (II) ion from polluted water. A design of experiments using the RSM approach was employed to evaluate and optimize the influence of carbonization temperature, ranging from 180 to 250 °C, with a residence time of 2–5 h. The predictive ability of the MINITAB-generated model was close to accurate, as demonstrated by the design application for process simulation. The maximum % hydrochar yield was 72.65% for the experimental yield and 71.53% for the predicted yield, both obtained from a sample carbonized at 166 °C for 3.5 h. Batch adsorption experiments were conducted to assess the hydrochar’s ability to remove Cu²⁺ from aqueous solutions, and the Langmuir and the Freundlich isotherms were fitted at different pH levels. A comprehensive characterization of the produced hydrochar was conducted using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray fluorescence (XRF), and scanning electron microscopy (SEM-EDS). The results revealed significant modifications in surface morphology, pore development, and the presence of oxygen-containing functional groups. Based on the findings in this report, it is safe to conclude that hydrochar derived from food waste could serve as a potential adsorbent. Overall, the study demonstrates that sustainable hydrochar production from biomass can simultaneously address waste management challenges and provide an efficient solution for heavy metal removal, thereby advancing circular bioeconomy and environmental protection. Full article

This article presents the results of the development of an antibacterial coating based on polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG) fibers with embedded silver nanoparticles. Silver nanoparticles were synthesized via the use of PEG, which acts as a reducing agent for Ag⁺ ions and a stabilizer for the colloidal system. The resulting sols were pink, dark purple, and orange color. The viscosity of the compositions, which increased with increasing PEG and AgNO₃ concentrations, was studied. The sizes of the synthesized silver nanoparticles were determined via dynamic light scattering. For all compositions, monomodal particle size distributions were obtained with characteristic sizes of 50.75, 58.73, 13.54 and 28.21 nm. The highest ζ-potential value for the silver nanoparticles was −15.5 mV, indicating their stability. The electrical conductivity of the compositions increased with increasing molar concentration of AgNO₃. The resulting PVP-PEG compositions with silver nanoparticles demonstrated resistance to pathogenic bacteria such as Staphylococcus aureus and Escherichia coli. A portable electrospinning device was developed at the Mendeleev University of Chemical Technology of Russia to apply the compositions to the skin and form a protective coating of PVP-PEG fibers with an antibacterial effect. Fiber formation was confirmed by scanning electron microscopy. The incorporation of silver into the fiber structure was confirmed by the results of elemental analysis and surface mapping of the samples. Full article

Rapid urbanization has intensified challenges regarding urban waterlogging and vehicle exhaust pollution. While permeable asphalt mixtures mitigate waterlogging and nano-TiO₂ offers photocatalytic exhaust degradation capabilities, the direct application of nano-TiO₂ is hindered by agglomeration and low photocatalytic efficiency. This study developed a composite modified nano-TiO₂ via metal ion doping and support treatment to enhance its performance in asphalt pavements. Specifically, nano-TiO₂ was doped with Fe³⁺, Ag⁺, and La³⁺ via the sol–gel method, and supported on activated carbon (AC) or Al₂O₃. The exhaust degradation performance was evaluated using a custom-built system, while dispersion properties were assessed via fluorescence microscopy and UV-Vis spectrophotometry. Furthermore, X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy were conducted to investigate the microstructural mechanisms underlying the doping modification and support treatment. Photocatalytic permeable asphalt mixtures were prepared by partially replacing mineral powder with the composite modified nano-TiO₂ to validate exhaust degradation and pavement performance. The results indicated that metal doping substituted Ti⁴⁺ in the lattice, inducing defects and reducing crystallite size to boost photocatalytic activity. The optimal doping concentrations are determined to be 1.0% for Fe³⁺, 1.5% for Ag⁺, and 1.0% for La³⁺. Among these, Fe³⁺-doped nano-TiO₂ at 1.0% content exhibits superior exhaust degradation, achieving 46.7% efficiency for hydrocarbons (HC) and 33.5% for nitrogen oxides (NO). Regarding dispersion, while AC performs better at low support content, Al₂O₃ at 40% content provides superior dispersion properties by increasing active sites and surface hydroxyl groups. For photocatalytic permeable asphalt mixtures, replacing 40–50% of mineral filler with the composite modifier is recommended. The optimized mixture demonstrates superior exhaust degradation performance while maintaining the required high-temperature stability, low-temperature cracking resistance, water stability, and fatigue life. Specifically, compared to the control group, these indicators for the mixture with 50% of the mineral filler replaced by the composite modifier increases by 7.0%, 12.5%, 13.4%, and 22.9%, respectively. This study presents a viable technical solution for developing multifunctional asphalt mixtures with photocatalytic functionality as the core innovation and mechanical performance as the application baseline. Full article

In this study, a polyethylene glycol (PEG)-based solid electrolyte composite (PEG)₁₀LiClO₄/NaAlOSiO suitable for anodic bonding packaging was successfully fabricated via a combined ball milling and hot pressing process. The micromorphology, ion transport characteristics, and mechanical packaging properties of the composite were systematically investigated using characterization techniques including electrochemical impedance spectroscopy, X-ray diffraction, scanning electron microscopy, and anodic bonding performance tests. The results demonstrate that doping with NaAlOSiO molecular sieve can effectively reduce the crystallinity of the polymer matrix, construct more efficient carrier transport pathways, and simultaneously enhance the ionic conductivity and mechanical properties of the material. When the mass fraction of NaAlOSiO doping is 8 wt.%, the composite exhibits a room temperature ionic conductivity of up to 1.31 × 10⁻⁵ S·cm⁻¹. Under room temperature and a bonding voltage of 800 V, the sample with this doping ratio achieves the optimal anodic bonding with metallic Al, and the tensile strength of the bonding interface reaches 5.93 MPa, showing excellent application prospects in micro–nano-packaging. Full article

This study reports that titanium nanoparticles can be used as a surface coating to enhance the corrosion resistance of 316 stainless steel. It specifically examines the influence of the deposition temperature (T_dep) on the coating’s structural and morphological properties, including corrosion behavior. TiO₂ nanoparticles were thoughtfully deposited on steel substrates at temperatures of 300, 400, and 500 °C using a horizontal hot-wall tubular reactor. This equipment was expertly engineered at the CIDETEQ laboratory through the metal–organic chemical vapor deposition (MOCVD) concept. Titanium isopropoxide [Ti(OC₃H₇)₄] was used as the precursor for the coating synthesis. Structural analysis was conducted using X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), and scanning electron microscopy (SEM). Corrosion performance was evaluated under accelerated conditions in 0.5 M H₂SO₄ using potentiodynamic anodic polarization (AP), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The corrosion test indicates that increasing T_dep significantly differentiates the coating morphology and improves corrosion resistance. AP revealed that the pitting potential (E_pit) shifted to more positive values, ranging from +1.4 to +1.5 V. CV voltammograms indicated that coated samples had lower passive current densities (I_p ≈ 10⁴ to 10⁵ A/cm²) than the bare substrate. EIS analysis demonstrated that the coating deposited at 500 °C processed the most favorable electrochemical performance, resisting corrosion for over 28 days. This coating achieved the highest electrical resistance (297 kΩ·cm²) and the lowest capacitance (2.7 μF/cm²), attributed to the formation of a crystalline anatase phase composed of pyramidal-like nanoparticle agglomerates (~40 nm). The dense packing structure effectively blocks charge-transfer pathways, restricting electron and ion transfer. Finally, MOCVD-based chemical surface modification with TiO₂ nanoparticles is considered an innovative method to improve the corrosion resistance of stainless steel, thereby prolonging its durability under accelerated sulfuric acid exposure. Full article