Spectroscopic Techniques Research Articles

Tailored Growth of Transition Metal Dichalcogenides' Monolayers by Chemical Vapor Deposition.

Here, results on the tailored growth of monolayers (MLs) of transition metal dichalcogenides (TMDs) are presented using chemical vapor deposition (CVD) techniques. To enable reproducible growth, the flow of chalcogen precursors is controlled by Knudsen cells providing an advantage in comparison to the commonly used open crucible techniques. It is demonstrated that TMD MLs can be grown by CVD on large scale with structural, and therefore electronic, photonic and optoelectronic properties similar to TMD MLs are obtained by exfoliating bulk crystals. It is shown that besides the growth of the "standard" TMD MLs also the growth of MLs that are not available by the exfoliation is possible including examples like lateral TMD1-TMD2 ML heterostructures and Janus TMDs. Moreover, the CVD technique enables the growth of TMD MLs on various 3D substrates on large scale and with high quality. The intrinsic properties of the grown MLs are analyzed by complementary microscopy and spectroscopy techniques down to the nanoscale with a particular focus on the influence of structural defects. Their functional properties are studied in devices including field-effect transistors, photodetectors, wave guides and excitonic diodes. Finally, an outlook of the developed methodology in both applied and fundamental research is given.

Engineering of self-assembled silver-peptide colloidal nanohybrids with enhanced biocompatibility and antibacterial activity

Several bacterial strains have developed resistance against commercial antibiotics, and interestingly, supramolecular nanomaterials have shown considerable advantages for antibacterial applications. However, the main challenges in adopting nanotechnology for antibacterial studies are random aggregation, compromised toxicity, multi-step preparation approaches, and unclear structure-function properties. Herein, we designed the amphiphilic tripeptide that acts as a reducing and capping agent for silver metal to form silver-peptide colloidal nanohybrids with the mild assistance of UV light (254 nm) through the photochemical reduction method. The nanohybrids are characterized by different spectroscopic and microscopic techniques, and non-covalent molecular interactions between metal and peptide building blocks confirm their central role in the formation of nanohybrids. The tripeptide is biocompatible and can reduce the toxicity of silver ions (Ag+) by reducing to Ag0. These colloidal nanohybrids showed antibacterial activity against gram-negative and gram-positive bacterial strains, and the possible mechanism of killing bacterial cells could be membrane disruption. This synthetic strategy is facile and green, which helps avoid using toxic chemicals or reagents and complicated methods for colloidal nanohybrid preparation for biomedical applications.

Metal-organic frameworks based on pyrazolates for the selective and efficient capture of formaldehyde

Indoor air pollution is one of the major threads in developed countries, notably due to high concentrations of formaldehyde, a harmful molecule difficult to eliminate. Addressing this purification challenge while adhering to the principles of sustainable development requires the use of innovative, advanced sustainable materials. Here we show that by combining state-of-the-art spectroscopic techniques with density-functional theory molecular simulations, we have developed an advantageous mild chemisorption synergistic mechanism using porous metal (III or IV) pyrazole- di-carboxylate based metal-organic framework (MOF) to trap formaldehyde in a reversible manner, without incurring significant energy penalties for regeneration. A straightforward, environmentally friendly, and scalable synthesis protocol was established for the porous, water-stable aluminum pyrazole dicarboxylate known as Al-3.5-PDA or MOF-303, capable of functioning as a highly efficient and reusable filter. It demonstrates selectivity and high storage capacity for formaldehyde under conditions typical of severe indoor use, such as in housing or vehicle cockpits, including varying VOC mixtures and concentrations, humidity, and temperature, without any accidental release. Furthermore, we have successfully regenerated this sorbent using a simple domestic protocol, ensuring the material reusability for at least 10 cycles.

Au(I) complexes installed on a self-assembled peptide efficiently catalyze intramolecular cyclization reactions.

Self-assembled peptides are used for diverse applications in the biomedical and technological fields. The morphology and function of the assembled systems are dictated by the peptide sequence and length. In this work, a supramolecular catalyst was obtained upon self-assembly of the diphenylalanine peptide conjugated to a triphenylphosphine Au(I) complex in acetonitrile. The assembled molecules were characterized by spectroscopic techniques and by scanning electron microscopy. The activity of the catalyst was tested on two substrates in cyclization reactions. The morphology and the dimensions of the assembled systems vary depending on the presence of a carboxyl versus an amide C-terminal end. The catalyst efficiently promotes intramolecular cyclization reactions. Results obtained encourage the use of self-assembled peptides for the obtainment of new and efficient catalysts.

In-silico Studies, Synthesis, and Antacid Activities of Magnesium (II) Complexes.

Nowadays, acidity is a severe problem worldwide caused by excessive gastric acid secretion by the stomach and proximal intestine. Antacids are drugs capable of buffering stomach acid. Therefore, in our research work, we have reported the in-silico studies, synthesis, characterization, and evaluation of antacid activities of magnesium (II) complexes via the acid-base neutralization process. In this research, some magnesium complexes were synthesized and their antacid behavior was compared with marketed products. Also, in-silico studies were performed on H+/K+ ATPase (Proton pump). All synthesized compounds were characterized by various spectroscopic techniques like UV-Vis, FT-IR, XRD, and DSC techniques. Spectroscopic analysis results showed that the semicarbazone ligand shows keto-enol isomerism and forms a coordinated stable complex with magnesium ions in the crystalline phase. The FT-IR results confirmed the presence of Mg-O stretching, N-H bending, and C=N stretching vibrations in Mg (II) complexes. The antacid activities of Mg (II) complexes were excellent as compared to the semicarbazone ligand and comparable with that of marketed antacid drugs like ENO, and Pantop-D. Insilco studies also confirmed that semicarbazone ligand and its Mg (II) complexes were both found to be fitted into the active sites of molecular targets, and Mg (II) complexes showed better binding affinities towards macromolecular as compared to semicarbazone ligand.

Synthesis, Antimicrobial and Antioxidant Activity of Some New Pyrazolines Containing Azo Linkages.

Pyrazolines and azo-pyrazolines are influential groups of heterocyclic compounds with two nitrogen atoms inside the five-membered ring. They play an important role in a wide range of biological processes, such as antifungal, antioxidant, antimalarial and other antimicrobial activities. The main objective of this study is to synthesize some new heterocyclic compounds with antioxidant and antimicrobial activity Methods: One-pot three components and traditional synthesis of new azo-pyrazoline compounds were achieved in this work. The preparation process has been started by diazotizing 4-(6-methylbenzothiazol-2-yl) benzamine and its coupling reaction with 4-hydroxy acetophenone producing azo-acetophenone, followed by benzylation with benzyl chloride to form the starting material, azo-benzyloxy acetophenone. A series of substituted benzaldehydes were reacted with the latter compound via one pot and classical methods, forming new chalcones containing azo linkages and benzyloxy moieties, which were then converted into new target azo-pyrazoline derivatives. The structures of the synthesized compounds were confirmed by spectroscopic techniques using FT-IR, 1H-NMR, 13C-NMR, and 13C- DEPT- 135 spectra. Finally, the synthesized compounds were screened for their antioxidant and antimicrobial activities against Staphylococcus aureus and Escherichia coli. Overall, the one-pot three-component synthesis of pyrazoline compounds generally provides advantages in terms of efficiency, simplicity, and time-consumption compared to classical synthesis methods. Hence, the study advocates the one-pot method because it eliminates the tedious process of making chalcones, which takes time, materials, and unnecessary effort. Therefore, this is the most convenient and effective approach to green chemistry.

Dendritic copper nanostructures for ultrasensitive detection of rhodamine 6G and Congo red

Surface-Enhanced Raman Scattering (SERS) is a fast-responding and non-destructive ultra-sensitive detection technique that can replace traditional chromatographic and spectroscopic analysis techniques. In this experiment, dendritic copper nanostructures were prepared by the solid-state ionics method and the vacuum hot evaporation process with an applied current of I=9μA. Using them as a SERS substrate, Raman detection was performed on the dye molecules Rhodamine 6G (R6G) and Congo Red (CR) to determine SERS enhancement performance. It is found that the growth of the prepared copper nanostructures has a top-end dominant phenomenon. The fractal dimension of the copper nanostructure was calculated using fractal theory, and it was revealed to be 1.560. Scanning electron microscopy (SEM) results showed that a large number of 60-80 nm regularly arranged copper nanoparticles were attached to the surface of the dendritic copper nanostructure. This is beneficial to increase the surface roughness of the substrate and improve the detection level of dye molecules. Subsequently, copper nanostructures can sensitively detect R6G and CR solutions as low as 1×10-13 mol/L and 1×10-7 mol/L, reaching single-molecule levels. The Raman mapping experiment showed that the mean relative standard deviation (RSD) values of R6G and CR were 12.3% and 12.9%, indicating high uniformity and reproducibility of the structure. This structure effectively achieves the fusion of uniformity, repeatability, and sensitivity, and shows broad application prospects in food detection.

Analysis of Eleonore Koch's artwork and powdered pigments from MAC-USP and Pinacoteca of São Paulo collections

Eleonore Koch is a German artist known for her paintings featuring arrangements of colors and ordinary objects. She spent a significant part of her life in Brazil, where she had the opportunity to interact with and learn from Alfredo Volpi, a colorist artist who introduced her to the tempera technique and the use of natural and mineral pigments, replacing oil-based industrial ones. A collection of powdered pigments she used during her lifetime was studied by spectroscopic analysis, forming an initial basis of knowledgement about Koch's pigments. In this paper, one painting from the Museum of Contemporary Art of the University of Sao Paulo (MAC-USP) collection was analyzed by spectroscopic (ED-XRF, Raman and FTIR) and imaging techniques. The painting palette was compared with some powdered pigments from the artist's collection. The pigments identified in the artwork are Chrome Oxide Green, Titanium White, Phthalocyanine Blue, Ivory or Bone Black and a yellowish/brown pigment rich in hematite. The findings indicate that most of the pigments found in Koch's artwork were also part of her personal collection.

Novel 3D plate-like g-C3N4/BiOCl heterojunction as a highly efficient photocatalyst for the degradation of carbofuran in wastewater under visible light irradiation

The g-C3N4/BiOCl (gCN-BCl) heterojunction photocatalyst was synthesized using a low-temperature precipitation method for effective photocatalytic degradation of carbofuran (CBF). All gCN-BCl composites demonstrate greater efficacy in removing CBF compared to its individual constituents. The synergistic effect of incorporating the 0D structured BiOCl onto the 2D structured g-C3N4 was comprehensively examined using various microscopic, X-ray, and spectroscopic analytical techniques. Additionally, optical and photoelectrochemical analyses were conducted. The findings validated that the interaction between the two semiconductors at the heterointerfaces enhanced remarkable physical and structural stability, promoted high charge separation and transfer properties, and improved photocatalytic degradation. Under optimal conditions, 5-gCN-BCl (0.25 g/L) achieved a CBF (5 mg/L) removal efficiency of 95.7 % under visible light irradiation of 120 min, achieving 3.1- and 5.9-times higher degradation rate than the pure BiOCl and g-C3N4, respectively. The radical trapping experiments indicated that the h+ and •O2− were the primary reactive species involved in the CBF degradation. Furthermore, the potential toxicity of CBF and its intermediates was assessed, revealing that the photocatalytic degradation process significantly lowered the ecotoxicity of pesticide wastewater. The potency of 5-gCN-BCl was also evaluated in tap water and real wastewater samples, with CBF degradation efficiencies of 85.8 %, 47.6 %, and 38.7 % in tap water, municipal, and pesticide industry wastewater, respectively. Additionally, artificial neural network (ANN) modeling was employed to predict and optimize the photocatalytic degradation process, providing further insights into the system’s performance. The outcomes of this work offer valuable insights into the development of heterojunction photocatalysts with superior stability and efficacy for eliminating pesticides from water bodies.

Photocatalytic degradation of cetirizine hydrochloride using polypyrrole decorated zinc ferrite nanohybrids under visible light irradiation.

The present work reports photocatalytic degradation of cetirizine hydrochloride (CTZ-HCl) utilizing polypyrrole (PPy) nanohybrids with ZnFe2O4 (ZnFe) nanoparticles. The synthesized materials were characterized using UV-visible spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), photoluminescence (PL) spectroscopy, BET, and scanning electron microscopy (SEM) techniques. UV diffuse reflectance studies (UV-DRS) revealed that the band gap was found to decrease with increase in the loading of PPy and Kubelka-Munk plots confirmed the bandgap values to be 2.14eV for ZnFe, 1.94eV for 1% PPy/ZnFe, 1.66eV for 3% PPy/ZnFe, and 1.38eV for 5% PPy/ZnFe. The photocatalytic performance against CTZ-HCl degradation was performed under visible light irradiation for 60min. The effect of catalyst dosage and the effect of drug concentration were investigated to confirm degradation behavior of the PPy/ZnFe photocatalysts. The degradation followed the pseudo-first-order kinetics model. Maximum photocatalytic degradation was observed to be 98% within 60min using 5% PPy/ZnFe as the photocatalyst. The recyclability tests revealed that the 5% PPy/ZnFe photocatalyst was reusable up to 4 cycles. Radical scavenging studies confirmed the generation of ●OH radicals that were responsible for the drug degradation. The degraded fragments were analyzed using LCMS technique and the tentative mechanism of degradation was proposed.

Organometallic Ru(III) Catalysts for α-Alkylation of Carbonyl Compounds using Alcohols: Mechanistic Insights via Detection of Key Intermediates.

Three novel cyclometalated ruthenium complexes ([Ru.L(9)] [Ru.L(10)] and [Ru.L(11)]) featuring azo functionalities were synthesized and characterized using a variety of spectroscopic techniques, namely FT-IR, electronic absorption spectroscopy, and ESI-MS. Representative solid-state structures of the acquired complexes were determined through X-ray crystallography. These complexes were evidenced to be efficient catalysts for the synthesis of various α-alkylated compounds utilizing simple acetophenone derivatives with easily affordable and economically viable alcohols, which were isolated and characterized via 1H and 13C NMR spectroscopy. The optimum reaction conditions were found by employing toluene as solvent, potassium tert-butoxide as base at 115 oC temperature utilizing 0.8 mol% of catalyst [Ru.L(10)]. The yield of the desired compounds found to be in the range of 83 - 97%. Additionally, mass spectrometry provided insights into the in-situ generated ruthenium hydride and ruthenium alkoxy intermediates, shedding light on the catalytic mechanism.

An Estimation of Baricitinib by AQbD-driven UV Spectrophotometry Development and Validation Process

Background: Baricitinib (BCTB) is a novel Janus Kinase (JAK) 1 and 2 inhibitor used in the therapy of rheumatoid arthritis, approved by the “Food and Drug Administration” in 2018. It has significant dose-dependent effectiveness and severe side effects. Thus, it is crucial to figure out its concentration in developed dosage forms. The literature search revealed that there has only been one UV spectroscopy technique documented up to this point. Methanol was chosen as the detection medium in this approach, which is not comparable with plasma or serum. As a result, the preliminary research suggested developing a UV spectroscopic approach that can estimate BCTB concentration and compare it to its concentration in the plasma or serum. Thus, in the proposed method, 7.4 pH phosphate buffer was selected as a mobile phase. Aim: Using the Analytical Quality by Design (AQbD) methodology, a simple, robust spectrophotometric method for the detection of BCTB in API form and Niosomes drug delivery system is designed and assessed. Methods: In the AQbD approach, a face-centered CCD design of Design Expert 13 software was used to evaluate two critical method variables: scanning speed and sampling interval. The design space suitability was confirmed by standard error and overlay plots. The 2-D contour and 3-D response surface plots were used to forecast the relationship between the response variable and predictor variables. Results: Baricitinib displays an absorption maximum at 249.40 nm in saline phosphate buffer pH 7.4. The distinguished linearity of the method was obtained over a concentration of 5–30 µg/ml with a correlation coefficient (R2 ) value of 0.998. BCTB % assay was found to be near 99 %. Intraday and Interday precision were found to have % RSDs of 0.067–0.488 and 0.146–0.942, respectively. Conclusion: The established spectrophotometric technique was observed to be precise as per ICH revised guidelines ICH Q2 (R1) and Q14 for analytical method validation. Our findings are instructional for the future design and development of safe and reliable therapeutic dosage forms of BCTB for rheumatoid arthritis.

Integrated adsorption and electrochemical sensing of Th(IV) ions using graphene oxide and chitosan decorated magnetite-based adsorbent.

Nuclear waste management is a crucial aspect as the most significant threat to the ecosystem is caused by radioactive waste in which thorium contamination remains a prominent issue. This work represents an integrated approach for the elimination of thorium through the adsorption technique and subsequent electrochemical sensing using Magnetite@Graphene Oxide@Chitosan (M@GO@Cs). Moreover, the sorption of Th(IV) ions is optimized through batch studies, which are consistent with the results derived from ANOVA using the Box-Behnken Design model, and the ideal parameters resulted in 95.79% removal efficiency of Th(IV) ions using 6 mg of adsorbent in 10 mL of 50 mg/L Th(IV) ions solution at a pH of 5 within 20 min. Maximum adsorption capacity (833.33 mg/g) is obtained from Langmuir adsorption isotherm and process was aligned with the pseudo-second-order kinetic model. M@GO@Cs exhibited high recyclability sustaining high performance across nine consecutive adsorption-desorption cycles while maintaining excellent removal efficiency upto 85%. Furthermore, the electrochemical characterization of the synthesized M@GO@Cs nanoadsorbent was studied using the Cyclic Voltammetry, and Electron Impedance Spectroscopy techniques and quantification of Th(IV) ions was done utilizing the Differential Pulse Voltammetry method with the Limit of Detection (LOD) of 0.2 mg/L within a linear range of 10-100 mg/L.

Syntheses of Novel Spirobenzazepinoindole Derivatives via Lewis-Acid Catalyzed Pictet-Spengler Cyclization.

The syntheses of novel spirobenzazepinoindole derivatives has been achieved through a highly efficient and synthetic route. The approach involves a two-step reaction, utilizing indole derivatives, 2-amino benzyl alcohol, and ninhydrin as key starting materials under mild reaction conditions. The reaction proceeds via a sequential cascade process involving cyclization, condensation and spiro-annulation, leading to the formation of the spirobenzazepinoindole core structure in good to excellent yields. The method offers broad substrate scope, high atom economy, and operational simplicity. The synthesized spirobenzazepinoindoles were fully characterized by spectroscopic techniques, including NMR (1H & 13C), IR and mass spectrometry. The methodology provides a valuable tool for the rapid generation of structurally complex spirobenzazepinoindoles, which could serve as scaffolds for the development of new therapeutic agents.

ASSESSMENT OF NEWLY SYNTHESIZED SALICYLALDEHYDE-BASED SCHIFF BASES AS CORROSION INHIBITORS FOR CARBON STEEL IN AQUEOUS ENVIRONMENT

A novel and eco-friendly approach for synthesizing two salicylaldehyde-based Schiff bases (2HPP and BHBD) in aqueous environments has been successfully conducted. These synthesized Schiff bases were subjected to a range of physicochemical analyses, including CHNS elemental analyses, molar conductivity measurements, and spectroscopic techniques like IR, electronic, 1HNMR, and mass spectra, to ascertain their properties. The research also involved investigating the inhibitory properties of these Schiff bases against mild steel corrosion in hydrochloric acid solutions at a temperature of 30°C. The results obtained from this study revealed the remarkable inhibitory potential of 2HPP and BHBD on mild steel corrosion in HCl solution. The inhibition efficiency was found to increase with increasing concentration, ultimately reaching an impressive maximum inhibition efficiency of 91.50% and 94.54 % for 2HPP and BHBD, respectively. The adsorption behavior of 2HPP and BHBD followed the Langmuir isotherm, indicating a favorable interaction with the metal surface. Moreover, the investigations included the use of quantum chemical parameters, which were computed utilizing the Density Functional Theory (DFT) method. These calculations included energy gap assessments, which lent support to the excellent inhibiting performance of both Schiff basses. However, BHBD appeared to be a more efficient inhibitor than 2APP.

Multifunctional hybrid films made from CoT3OTx4 and CoFeT2OT4 nanoparticles inside a poly 3-hydroxybutyrate matrix and study of their impact in methyl orange photodegradation.

This work aims to produce hybrid materials with potential applications in dye photodegradation. Therefore, hybrid films were obtained by incorporating cobalt (II, III) oxide (Co3O4) or cobalt ferrite (CoFe2O4) nanoparticles (NPs) with 18 ± 1.6 nm and 26 ± 1.3 nm, respectively, into a poly 3-hydroxybutyrate (P3HB) polymeric matrix. The Co3O4@P3HB and CoFe2O4@P3HB hybrid films were fabricated by solvent casting in a ratio of 85 mg to 15 mg (P3HB-NPs). Different spectroscopic and microscopy techniques characterized the Co3O4 and CoFe2O4 NPs and the P3HB, Co3O4@P3HB and CoFe2O4@P3HB films. The optical band gap for Co3O4 and CoFe2O4 NPs was estimated from their diffuse reflectance spectra (DRS) around 2.5 eV. X-ray diffraction (XRD) of the hybrid films revealed that the nanometric sizes of the Co3O4 and CoFe2O4 nanoparticles incorporated into the P3HB are preserved. The magnetic hysteresis curve of CoFe2O4 nanoparticles and CoFe2O4@P3HB film showed a ferromagnetic behaviour at 300 K. Transmission electron microscopy (TEM) confirmed the formation of nanocrystals, and scanning electron microscopy (SEM) provided evidence for the successful incorporation of the NPs into the P3HB matrix. The surface roughness and hydrophilicity of the hybrid films are increased compared to the P3HB film. The impact of the nanoparticles and the hybrid films on the photodegradation of methyl orange (MO) in its acidic form was studied. The photodegradation tests were carried out by direct sunlight exposure. The CoFe2O4@P3HB hybrid film achieved 85% photodegradation efficiency of a methyl orange solution of 20 ppm after 15 minutes of exposure to sunlight. After 30 minutes of exposure to sunlight, the nanoparticles and the hybrid films reached about 90% of the MO degradation. The results suggest that combining nanoparticles with the polymer significantly enhances photodegradation compared to isolated nanoparticles.

Recent Progress in Nanomaterial-Based Surface-Enhanced Raman Spectroscopy for Food Safety Detection

Food safety has recently become a widespread concern among consumers. Surface-enhanced Raman scattering (SERS) is a rapidly developing novel spectroscopic analysis technique with high sensitivity, an ability to provide molecular fingerprint spectra, and resistance to photobleaching, offering broad application prospects in rapid trace detection. With the interdisciplinary development of nanomaterials and biotechnology, the detection performance of SERS biosensors has improved significantly. This review describes the advantages of nanomaterial-based SERS detection technology and SERS’s latest applications in the detection of biological and chemical contaminants, the identification of foodborne pathogens, the authentication and quality control of food, and the safety assessment of food packaging materials. Finally, the challenges and prospects of constructing and applying nanomaterial-based SERS sensing platforms in the field of food safety detection are discussed with the aim of early detection and ultimate control of foodborne diseases.

Fluorescent Microscopy Investigation of Cytotoxic Impact on MCF-7 Cell Line Treated With Zinc Nanoparticles Synthesized From Jania rubens.

Zinc nanoparticles (ZnNPs) are a viable option in a number of disciplines, including cancer treatment, due to their special features. Among the several techniques for synthesizing ZnNP, biosynthesis with natural extracts is a highly effective and environmentally benign method, especially for uses in biomedicine. Using an aqueous extract of the marine red seaweed Jania rubens, we created a unique biosynthetic technique in this study to manufacture ZnNPs. The produced ZnNPs have a characteristic flower-like form, as seen by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The effective production of ZnNPs and the involvement of biomolecules in the synthesis process were validated by energy-dispersive X-ray spectroscopy (EDAX) and Fourier transform infrared spectroscopy (FTIR) techniques. Using the MTT assay, the cytotoxic effects of the biosynthesized ZnNPs were evaluated, indicating their ability to inhibit MCF-7 breast cancer cells. Furthermore, ZnNPs' cytotoxicity against MCF-7 cells was validated by live/dead imaging experiments, which supported the MTT results.

Spatial distribution of corrosion products from a bridge pier

AbstractThis paper studies the spatial distribution of corrosion by-products by a bridge pier within a conductive medium. An electrochemical impedance spectroscopy (EIS) technique was used to investigate an uncoated metallic bridge pier submerged in static distilled water. An equivalent circuit model, derived from EIS results, served as the foundation for the study. Further, the role of diffusion was analysed, considering its significance in characterising the transfer of particles from the pier into the surrounding water. This exploration revealed the complex interaction between the diffusion processes of various corrosion by-products as a function of distance. In addition, by evaluating the spatial distribution of iron (II) corrosion by-products and modelling nanoparticle diffusion, the research examined the impact of diffusion and concentration on corrosion particle transmission. The findings, analysed via Nyquist and Bode plots, demonstrate significant differences between theoretical and empirical diffusion coefficients. Results indicated that under natural corrosion conditions, the primary product of the corrosion reaction, iron (II), disperses into the medium when oxidation occurs. The elevated resistivity due to the presence of iron (II) underscores the diffusion effect, leading to corrosion product precipitation and reaching saturation level. Additionally, the results demonstrated ideal values for the diffusion coefficient, which are crucial for advanced corrosion modelling. The results emphasised the need for empirical data to improve corrosion prediction models and informed maintenance strategies for submerged structures.

Impacts of distorted local chemical coordination on electrochemical performance in hydrated vanadium pentoxide

Modulating and elevating the operating voltage of a given cathode is a significant challenge to enhance the energy density of secondary batteries without sacrificing power output. The chemical coordination strongly influences the energy levels of d-orbitals of redox cations in cathode materials, which tie to their operating voltage. In contrast to concentrated studies on enhancing the specific capacity, in this study, we choose bi-layered hydrated vanadium pentoxide as the model to modulate the d-orbital energy levels through local chemical coordination manipulation, achieving a higher operating voltage in rechargeable aqueous zinc ion batteries. Here we show that, by employing X-ray absorption spectroscopy (XAS) and pair distribution function (PDF) techniques, we can analyze the distortion of [VO6] octahedra and extract chemical bond information, deciphering the correlation between the chemical coordination and operating voltage in cathode materials. The fundamentals could guide the designing and developing RAZIBs with higher energy and power density.