Electrical Neutrality Research Articles

COMPOSITION AND THE RELATIVE STABILITY OF SULFUR DIOXIDE INTERACTION PRODUCTS WITH POTASSIUM AND MONOETHANOLAMMONIUM TAURATES AQUEOUS SOLUTIONS. PROLONGED-ACTION CHEMOSORBENT

Much research attention has been paid to amino acids as an alternative to amino alcohols for capture of sulfur dioxide. Taurine (Tau) occupies a special place among amino acids. This study was stimulated by the limited literature data on the nature of the interaction of SO2 with Tau salts aqueous solutions, the composition and relative stability of the corresponding reaction products. Chrono-pH-, chrono-redox- and chrono-conductometric studies of SO2 chemisorption with potassium taurate (TauK) and monoethanolammonium (TauMEA) aqueous 0.1 M solutions were carried out in the temperature range 293–313 K to study these processes. The maxima on the differential pH-metric titration curves positions coincide with the positions of the jumps on the integral and maxima on the redox-metric titration differential curves, as well as with breaks on the conductometric curves position. Δk negative values indicate the formation of weakly dissociated particles or less mobile ions in the solutions under study that is confirmed by the data of mathematical calculations. Using a mathematical model that takes into account the law of mass action, material balance and electrical neutrality principle, SO2 – TauK – H2O solutions ion-molecular composition and ionic strength were calculated. With an increase in the chemisotption SO2 amount, the taurate anions concentration decreases due to the hydrolytic transformation into zwitter ions +NH3CH2CH2SO2O - and the sequential transformation of hydrotaurate-sulfite (4:1 and 2:1; I and II), taurate-sulfite (2:1; III), hydrotaurate-hydrosulfite (2:1; IV) and taurate-hydrosulfite (1:1; V) associates. The concentration and thermodynamic constants for the formation ionic associates I–V were calculated. TauK input into impregnated fibrous chemisorbents (IFCS) composition obtained by impregnating viscose fibers with monoethanolamine aqueous 0.25 M solutions (IFCS-0.25MEA) leads to a synergistic increase in quantity of adsorbed SO2. IFCS-0.25MEA-TauK are long-acting sulfur dioxide chemisorbents, and TauK itself serves as a promoter-modifier towards IFCS-0.25MEA preventing the MEA removal from IFCS surface by the GPS flow due to the ionic associates formation and promoting deeper HOCH2CH2NH2 «response».

Influence mechanism of direct current electric field on the sulfur removal of fluorine-containing spent refining slag

To promote the recycling of spent refining slag effectively, the effect of direct current (DC) voltage (0–4 V) on sulfur migration, structure and properties of CaO-SiO2-Al2O3-MgO-F-S slag with 4–7 wt% F was investigated at in present study. It was concluded that with the increase of voltage, the slag network structure depolymerized, the melting temperature decreased, and the sulfur removal rate increased. Thereinto, the highest mobility of sulfur removal, which was up to 85%, was achieved when the voltage was 4 V with the slag containing 5 wt% F. The coupled electrochemical mechanism of sulfur migration was reflected by the comprehensive effect of cathodic and anodic reactions. In the slag, Ca2+ and Mg2+ undergone cathode reaction, some of which generated gas overflow and some migrated to molten steel, while the [SiO4]4- cathodic reaction had less influence on electrochemical balance. To maintain electrical neutrality, S2- in the slag underwent anodic reaction and migrated to the molten steel, while CO generated by the anodic reaction at slag-metal interface led to large size gas holes. However, the loss of electrons of Fe2+ and Fe3+ caused negative electrons to accumulate at the slag-metal interface, which formed the charge resistance of sulfur migration. Collectively, as voltage increased in the range of 0–4 V, the electric field force enhanced, diffusion resistance depleted and charge resistance aggregated, resulting in an overall increase in sulfur migration from spent refining slag to molten steel.

CITRIC ACID–SODIUM CITRATE–WATER SOLUTIONS ACID-BASE AND ELECTROCHEMICAL BEHAVIOR

The protolytic equilibria in the system citric acid (H3Cit)–sodium citrate (Na3Cit)–water at a total content of citrates forms (citric acid, dihydrocitrate (H2Cit-), hydrocitrate (HCit2-) and citrate (Cit3-) anions) 1.0 mol/l have been studied by pH- and conductometric methods in the temperature range 293 ÷ 313 K. The first concentration ranges at which pH – lg(νH3Cit/νNa3Cit) and κ – CNa+/Ccit functions are linear correspond to the H3Cit/H2Cit- buffer system; the second ones – to H3Cit/H2Cit- and H2Cit-/HCit2-; the third ones to – HCit2-/Cit3- buffer system. The investigated solutions ion-molecular composition and ionic strength (m, mol/l) have been calculated using the mathematical model taking into account the law of mass action, material balance for citrates and electrical neutrality principle. The ionic strength concentration dependences have a complex character due to the ion-molecular composition multicomponent nature for the studied solutions. The ionic strength values are directly proportional to the ratio [Na+]/CCit in the concentration intervals 0 ≤ [Na+]/CCit ≤ 1.0 and 2.0 ≤ [Na+]/CCit ≤ 3.0. In the concentration range 1.0 ≤ [Na+]/CCit ≤ 2.0, the values of m = 1.15 ± 0.27 mol/l) weakly depend on the [Na+]/CCit ratio and practically do not depend on temperature. Citric acid concentration and thermodynamic constants for the first, second, and third dissociation stages have been determined. The obtained data on the acid-base and electrochemical characteristics of the solutions HOC3H4(COOH)3 – HOC3H4(COONa)3 – H2O(СCit = 1.0 mol/l; СNa+ = 0 ÷ 1.0 mol/l) can be used in chemical analysis, microbiological and biochemical studies, and the acidity data of the solutions studied can simulate chemisorption of acidic (SO2) and/or basic (NH3) gases.

Antifouling Electrochemiluminescence Biosensor Based on Bovine Serum Albumin Hydrogel for the Accurate Detection of p53 Gene in Human Serum.

To detect biomarkers in complex samples, it is fundamental to avoid the nonspecific adsorption of impurities to improve the selectivity of biosensors. In this study, a sensitive antifouling electrochemiluminescence biosensor was proposed based on bovine serum albumin (BSA)- and exonuclease III (Exo III)-mediated nucleic acid cycle signal amplification strategy. Ti3C2Tx-NH4, which has a large surface area and high metal conductivity, was crosslinked with BSA to improve the conductivity of the sensing interface, which shows antifouling performance excellently due to the electrical neutrality and good hydrophilicity of BSA hydrogel. The cyclic amplification strategy based on Exo III and DNA hybridization chain reaction significantly amplified the electrochemiluminescence signal and improved the sensitivity of p53 gene detection. The linear range of the biosensor is 1 fM-1 nM with a detection limit of 0.26 fM. More importantly, the sensor showed excellent selectivity when it was used to detect the p53 gene in real samples, such as serum. Thus, this unique antifouling sensing interface is expected to construct various electrochemical biosensors in clinical diagnosis and biopathological analysis.

A simple procedure for accurately assessing the stoichiometry and structural disorder of TiN ceramics by X-ray diffractometry

Accurately assessing the stoichiometry and structural disorder of TiN ceramics is very important for understanding their properties, but is often not done because it requires complex Rietveld refinements of the corresponding X-ray diffraction (XRD) patterns. As an alternative, a simple procedure is developed here that allows such information to be extracted from the XRD patterns without Rietveld refinements. For this purpose, the stability ranges of super-stoichiometric and sub-stoichiometric TiN are first determined theoretically mathematically from the general principles of Wyckoff position occupation and electrical charge neutrality, and then constrained by theoretical thermodynamic calculations of the Gibbs potential. Subsequently, theoretical simulations of the XRD patterns of a large set of super-stoichiometric and sub-stoichiometric TiN ceramics in their stability ranges are used to reveal the existence of linear relationships between the stoichiometry and the intensity ratio of the hkl peak to the 200 peak (i.e., Ihkl/200 (%) with hkl being 111, 220, 311, 222, 400, and 331), which is then exploited to formulate an analytical model that easily assesses the stoichiometry and structural disorder of TiN ceramics from I111/200 (%). Finally, as an experimental validation and example of application, the stoichiometry of a TiN ceramic fabricated by spark plasma sintering is experimentally evaluated using both the Rietveld method and the proposed model showing marked agreement between their results.

High entropy BaFe12-x(Ti/Mn/Ga/In)xO19 (x = 1–7) oxides: Correlation of the composition, entropy state, magnetic characteristics, and terahertz properties

The BaFe12-x (Ti/Mn/Ga/In)xO19 (x = 1–7) high-entropy oxides (HEOs) were obtained by solid-phase synthesis. The correlation of the chemical composition (the level of the Fe replacement), structural parameters, magnetic characteristics, and terahertz (THz) properties was investigated. All studied samples were single-phase (SG: P63/mmc). Lattice parameters showed a monotonic increasing trend with an increase of (x). The key role in increasing the lattice parameters of HEOs may belong to the influence of In3+ ions, which are much larger in size than Fe3+ ions. As one of the possible reason for explanation of the lattice parameters behavior we hypothesized that partial charge transformation of the Mn3+ state to the Mn2+ state takes place in order to maintain electrical neutrality. Other cations (Ti/Ga/In) have stable oxidation state. The anisotropic nature of the increase in lattice parameters was demonstrated. No strong correlation between chemical composition and microstructural parameters of the investigated HEOs was observed. The magnetic characteristics of the BaFe12-x (Ti/Mn/Ga/In)xO19 (x = 1–7) HEOs were investigated at broad intervals of magnetic fields and temperatures. The behavior of the magnetic characteristics was shown to be the result of the magnetic structure frustration. In addition, terahertz electrodynamic properties were studied by measuring spectra of complex dielectric permittivity at frequencies 0.2–1.2 THz in the temperature interval 20–300 K. The spectra indicate the presence of a higher-frequency infrared phonon resonance, whose damping decreases with cooling, as well as an excitation below 0.2 THz that freezes out at low temperatures, the origin of which is associated with the polycrystalline nature of the materials.

A centrifugal microfluidic platform for rapid detection of pathogens based on chitosan nucleic acid extraction and RAA-T7-CRISPR/Cas13a nucleic acid detection

This study reported a bacterial detection platform using chitosan electrostatic adsorption for nucleic acid purification, RAA-T7-CRISPR/Cas13a system for nucleic acid quantification and centrifugal microfluidic platform for full-automatic operation. First, the nucleic acids in the lysed bacterial sample were captured by chitosan modified in the microfluidic PDMS channel through electrostatic adsorption, followed by washing with sodium acetate buffer solution. Then, these captured nucleic acid templates were eluted using Tris-HCl buffer solution through restoring the electrical neutrality of chitosan. Finally, the eluted nucleic acid templates were transferred into the RAA-T7-CRISPR/Cas13a system and isothermally amplified at 37 °C, followed by real-time detection of fluorescent products. A centrifugal microfluidic chip was elaborately designed with a chitosan modified channel, eight functional chambers and three siphon valves to achieve sequential capture, washing, elution, amplification and detection of nucleic acids. This platform has the capacity of automatically detecting Salmonella within 1 h. The detection limit of this platform was 10 CFU/mL in chicken supernatant under the use of optimal conditions. The average recovery and standard deviation of this platform are 106.9% and 6.4%, respectively.

Design, development, and in-vitro/in-vivo evaluation of docetaxel-loaded PEGylated solid lipid nanoparticles in prostate cancer therapy

Docetaxel (DOC) is a potent anticancer molecule widely used to treat various cancers. However, its therapeutic efficacy as a potential anticancer agent has been limited owing to poor aqueous solubility, short circulation time, rapid reticuloendothelial system uptake, and high renal clearance, which consecutively showed poor bioavailability. In the present investigation, we developed polyethylene glycol (PEG) decorated solid lipid nanoparticles (SLN) using the solvent diffusion method to increase the biopharmaceutical properties of DOC. PEG monostearate (SA-PEG2000) was initially synthesized and characterized using various analytical techniques. Afterwards, DOC-loaded SLN was synthesized with and without SA-PEG2000and systematically characterized for in-vitro and in-vivo properties. Spherical-shaped SA-PEG2000-DOC SLN showed hydrodynamic diameter and zeta potential of 177 nm and −13 mV, respectively. During the in-vitro release study DOC-loaded SLN showed a controlledrelease of approximately 54.35 % ± 5.46 within 12 h with Higuchi release kinetics in the tumor microenvironment (pH 5.5).In an in-vitro cytotoxicity study,SA-PEG2000-DOC SLN showedsignificantlylower IC50values(p < 0.001)compared to DOC-SLN and DOC aloneagainst prostate cancer cell lines (PC-3). Similarly, an in-vitro cellular uptake study showed a significant increase in intracellular DOC concentration for SA-PEG2000-DOC SLN. Additionally, inin-vivostudies,PEGylated SLN of DOC showed around 2- and 15-fold increase in the maximum concentration of drug (Cmax) and area under the curve (AUC), respectively, as compared to plain DOC solution due to the uniquehydrophilicity and hydrophobicity balance and electrical neutrality of specially designed PEG architect. The biological half-life (t1/2) and mean residence time (MRT) was found to increase from 8.55 and 11.43 to 34.96 and 47.68 h, respectively, with SA-PEG2000-DOC SLN. Moreover, the bio-distribution study indicates high DOC concentration in the plasma which signifies the more pronounced blood residence time of SA-PEG2000-DOC SLN. In a nutshell, SA-PEG2000-DOC SLNwasfound to bea promising and efficient drug delivery platform for the management of Metastatic Prostate cancer.

Influence mechanism of plant litter mediated reduction of iron and sulfur on migration of potentially toxic elements from mercury-thallium mine waste

The decomposition of plant litter in soil changes soil nutrient content and plays an important role in regulating soil pH and availability of potentially toxic elements (PTEs). However, there remains limited studies on the mechanism under which litter influences the transport of PTEs in the process of ecological restoration. This study examined the effect of plant litter decomposition mediated reduction of iron and sulfur components on migration of PTEs from mercury-thallium mine waste. The results showed that the four kinds of litter alleviated the acidity of the waste, especially the Bpa and Tre litter. The nitro and nitroso groups produced by the decomposition of the litter were adsorbed onto the waste, thereby providing an electron transfer medium for iron reducing microorganisms, such as Geobacter. This promoted the reduction and release of Fe3+ to Fe2+ and reduced the electronegativity (El) value of waste. The reduced El promoted the adsorption of metal cations such as Hg and Tl to maintain electrical neutrality. However, it was not conducive to the adsorption of oxygen containing anions of As and Sb. An increase in litter resulted in an increase in reductivity of mercury-thallium mine waste. This maintained the reduction of Fe3+ to Fe2+ and changed or destroyed the structure of silicate minerals. PTEs, such as Tl, Hg, As, and Sb, were released, resulting in reductions in their residual fraction. However, the strong reduction conditions, especially the decomposition of Bpa, caused part of the released Hg(II) combining with S2− produced by the reduction of SO42− to form insoluble HgS, thereby reducing its migration. The findings could provide a theoretical basis to guide the situ-control and ecological restoration of PTEs in waste slag site.

Physicochemical Analysis of Chloride Diffusion and Adsorption in Water-saturated Concrete: Theory and Measurement

The theory of ionic diffusion in water-saturated concrete accompanying ion exchange with mobile or immobile adsorbed ions was constructed by using the general theory of diffusion and the condition of electrical neutrality. Analysis of the diffusion profile of chloride (Cl−) ions in concrete with the theory revealed that adsorbed Cl− ions in AFm and C-S-H are as mobile as free Cl− ions in the pore solution, so that the adsorption does not retard the ingress of Cl− ions. The existing test methods for determining the effective or apparent diffusion coefficient of Cl− ions were evaluated on the bases of the present theory and new experimental findings. It was revealed that steady-state electrochemical methods such as NTBUILD-355 and ASTM C1202 are not suitable for determining the diffusion coefficient, because the steady state methods expel preexisting diffusible ions which strongly affect the diffusion of Cl− ions. Moreover, the steady state methods overestimate the diffusion rate because the methods assume that adsorbed Cl− ions are immobile. The electrochemically-accelerated method NT BUILD 443 is also unsuitable for the diffusion test, because the acceleration is induced by the electro-osmotic flow of the external solution into concrete. The present diffusion theory necessitates the effective self-diffusion coefficient of not only Cl− ions but also all the other diffusible ions in concrete. A simple method of determining the effective self-diffusion coefficients of arbitrary ions in concrete from the diffusion profile of Cl− ions was presented.

SELECTIVE SORBENTS BASED ON DIAMINODICYCLOHEXYLCROWN ETHERS

Macromolecules with crown ether groups are a fundamentally new type of sorbents whose active centers are ligands that retain electrical neutrality in the process of simultaneous binding of cations, anions, or organic compounds. The purpose of this work is to create new selective sorbents based on diaminodicyclohexylcrown ethers and to study their complexing properties with respect to alkali metal ions. Methodology. To study the composition and properties of the products of the synthesis of crown ether-containing sorbents, chemical and physicochemical methods of analysis were used: infrared spectroscopy, atomic absorption spectrophotometry. Results and discussion. Chemical grafting of cycloaliphatic crown ethers onto a macroporous chloromethylated copolymer of styrene and divinylbenzene has been carried out. Under the chosen conditions, when using diaminodicyclohexyl-18-crown-6, polycrown ethers were obtained with a content of crown ether grains of 1.42 mmol/g, when using diaminodicyclohexyl-24-crown-8, the content of macrocyclic groups was 1.24 mmol/g. The extraction of alkali metals under static conditions by grafted sorbents based on various macrocycles has been studied. The high values of the distribution coefficients of alkali metals (Na+, K+, Cs+) by the synthesized sorbents in an acidic medium are shown. The following selectivity series were found for the sorbent with diaminodicyclohexyl-18-crown-6 fragments: K+ ˃ Cs + ˃ Na+, and for the sorbent with diaminodicyclohexyl-24-crown-8 fragments: Cs+ ˃ K+ ˃ Na+ metals. Conclusion. The efficiency of extracting metal ions from aqueous solutions containing Crown esters is affected by the presence of amino groups. It is known that the amino group promotes the formation of a polymer that swells in water. It was noted that the use of sorbents based on polymers that swell in water when metal salts are removed from the aqueous medium leads to an increase in the sorption capacity of sorbents by facilitating the access of metal ions in water to the active areas of the immobilized sorbent.

Perspective on Biomass-Based Cotton-Derived Nanocarbon for Multifunctional Energy Storage and Harvesting Applications

The demand for renewable-energy-based efficient systems is a practical indication to develop sustainable energy nanomaterials for energy storage and conversion to reduce the use of pollution-based nonrenewable energy systems. The use of biomass-derived energy components is a new age for the development of sustainable energy electrode nanomaterials. Among biomass, cotton-based electrodes are more popular, as they are cost-effective and efficient energy materials. Cotton-plant-derived porous or pristine nanocarbons have good textural and morphological properties with high specific surface area, hierarchical porous structure, and large pore volume. The functionalization, addition of active moieties, and easy synthetic routes improve the properties and enhance the performance of various electronic devices. The functionalization of derived materials with a heteroatom perturbs the electrical neutrality of the framework. The incorporation of active sites enhances the surface area and creates defects in the framework. These properties speed up the charge storage and energy conversion reaction for better performance of fabricated devices. This Review gives a detailed understanding and advancements about cotton-derived energy nanomaterial. Also, it gives insight about the key factors affecting the performance of cotton-based electrodes, electrolytes, and other components of energy devices. This Review concludes with the cotton-plant-derived supercapacitor, fuel cell, and battery, with a deep insight into their physicochemical properties. This Review also discusses the role of the active mass of the material used for the different device fabrications, which alters the performance. Further, a deep insight has been provided with a brief discussion of other electronic devices like photovoltaic, triboelectric, and piezoelectric devices based on cotton-derived nanocarbon.

Rapid and selective removal of Pb ions by electroactive titanium Dioxide/Polyaniline ion exchange film

The slow accumulation of heavy metal in the sediment and aquatic food chain, leads to extremely bad health influence in human body. Most of the traditional adsorption materials have deficient adsorption capacity and selectivity. In this research, the TiO2/PANI composite material is synthesized successfully by intercalating 2HT (intercalating agent) and PANI into the interlayer of the TiO2 nanosheet for the separation of Pb2+. During this synthesis process, the layer spacing of TiO2/PANI can be controlled precisely by adjusting the concentration of 2HT and PANI. The rapid Pb2+ uptake/ release process is triggered through turning the redox states of composite film which can leads to the conversion between Ti4+ and Ti3+ and the conversion between –OH and -O-Pb covalent bond for maintaining the electrical neutrality. In addition, the directional H+ proton migration, fast electronic transporting network and superfast Pb2+ ion transport path both are benefit for the transmission and uptake of Pb2+. As a result, this composite film illustrates ultrahigh uptake capacity (1499.99 mg∙g−1) and selectivity (KD = 15.2 L·g−1). It can even treat real wastewater to a level lower than WHO. Hence, this composite film with superior electrochemical performance is a promising material, which could be used for uptake/release of Pb2+.

Engineering excellent Pd/CeO2-ZrO2-Al2O3 catalyst with abundant oxygen vacancies by Pr surface modification for eliminating NO and C3H8

In this work, a series of aliovalent additives M (M=La3+, Nd3+, Pr3+/4+, and Y3+) have been introduced to CeO2-ZrO2-Al2O3 (CZA) to increase the surface oxygen vacancies by surface modification according to electrical neutrality principle, in which Pr exhibited the most significant promotion effect. Then by in-situ infrared, X-ray photoelectron spectroscopy (XPS) and CO-Fourier transform infrared spectroscopy (CO-FTIR) measurements, it could be indicated that Pr/CZA with increased oxygen vacancies can establish strong electronic interactions with the supported Pd species, which stabilizes the Pd species in oxidation states and smaller particle size for achieving more active centers. Meanwhile, more monodentate nitrate/nitrite intermediates, which are highly active to be transformed by C3H8, could easily be formed on the surface of modified Pd/Pr/CZA catalyst. As a result, the Pd/Pr/CZA exhibited the best conversion efficiency of C3H8 and NO, the T90 (the light-off temperature at 90 % conversion) of which was reduced by 25 °C and 20 °C comparing with that of Pd/CZA even being thermally aged at 900 ℃ for 6 h, respectively.

A Self‐Sustained Charge Neutrality Intracloud Lightning Parameterization Containing Channel Decay and Reactivation

AbstractA self‐sustained charge neutrality parameterization scheme of intracloud (IC) lightning is presented in this paper. The scheme contains the following features: simultaneous development of multiple branches, polarity asymmetry of positive and negative leaders, nonlinear electrical parameters, complete charge neutrality, and channel decay and reactivation. Nonlinear electrical parameters and charge neutrality are the key factors that determinate channel decay and reactivation. To demonstrate the simulation capacity of this scheme, two simulated intracloud flashes by this scheme under the tripole charge structure are chosen for analysis. These two IC flashes show clearly the above features, where reactivation processes that initiated from different branches and the real‐time changes in nonlinear electrical parameters are mainly analyzed. The simulation results are in line with the current knowledge on lightning, which also suggests that the new scheme may become a useful tool to deeply explore the discharge phenomena involving channel decay and reactivation.

Osmotic-Enhanced-Photoelectrochemical Hydrogen Production Based on Nanofluidics

Osmotic-Enhanced-Photoelectrochemical Hydrogen Production Based on Nanofluidics

Exploring the dielectric and conduction characteristics of iodine substituted CaCu3Ti4O12-xIx

AC electrical measurements were carried out on iodine doped, CaCu3Ti4O12-xIx (x = 0, 0.005, 0.05 and 0.2) ceramic specimens sintered at 1100 °C for 12 h in the temperature (300–450 K) and frequency (20 Hz - 1 MHz). The crystalline structure, microstructure, and oxidation state of various ions of pure and iodine-substituted sintered specimens were carried out through XRD, SEM, and XPS, respectively. The dielectric relaxations in grains, grain boundaries, and sample-electrode interfaces for different compositions were investigated through impedance and modulus spectroscopic techniques and were reported in the first part of the investigation. It revealed the involvement of similar types of charge carriers in conduction and relaxation processes in grains and grain boundaries, respectively. This second section emphasizes the dielectric and conduction properties of CaCu3Ti4O12 (CCTO) with iodine doping at the anion site. The XPS study reveals that the concentration [VO••] is reduced, and [VM″] gets increased with increasing concentration of iodine from x = 0.05 to 0.2. This observation also supports the point defect model as reported earlier for charge compensation of impurity defect IO• i.e., with increasing substitutions of iodine, the charge on IO• change from electronic to cationic vacancies, VTi//// or copper VCu// or both to keep electrical charge neutrality. The metal ions get segregated at grain boundaries. This, in turn, will minimize hopping due to electrons between Ti4+ and Ti3+ or Cu2+ and Cu1+. As a result, it increases resistivity and minimizes dielectric losses for the higher concentration of iodine doping. Thus, a high concentration of iodine doping at the oxygen site promotes the formation of a barrier layer capacitor.

Spatial Band Separation in a Surface Doped Heterolayered Structure for Realizing Efficient Singlet Oxygen Generation.

Singlet oxygen (1 O2 ) with electrical neutrality and long lifetime holds great promise in producing high-added-value chemicals via a selective oxidation reaction. However, photocatalytic 1 O2 generation via the charge-transfer mechanism still suffers from low efficiency due to the mismatched redox capacities and low concentration of photogenerated carriers in confined systems. Herein, by taking bismuth oxysilicate (Bi2 O2 SiO3 ) with alternating heterogeneous layered structure as a model, it is shown that iodine doping can facilitate the spatial redistributions of bands on alternated [Bi2 O2 ] and [SiO3 ] layers, which can promote the separation and transfer of photogenerated charge carriers. Meanwhile, the band positions of Bi2 O2 SiO3 are optimized to match the redox potential of 1 O2 generation. Benefiting from these features, iodine-doped Bi2 O2 SiO3 exhibits efficient 1 O2 generation with respect to its pristine counterpart, leading to promoted performance in the selective sulfide oxidation reaction. A new strategy is offered here for optimizing charge-transfer-mediated 1 O2 generation.

Crevice Corrosion Behavior of Alloy 690 in High-Temperature Aerated Chloride Solution.

Crevice corrosion behavior of Alloy 690 in high-temperature aerated chloride solution was studied using a self-designed crevice device. The SEM, EDS, XRD, and XPS analyses results indicated that the oxide films outside the crevice consisted of Ni-Cr oxides containing a small amount of hydroxides, and the oxide films on crevice mouth consisted of a (Ni,Fe)(Fe,Cr)2O4 spinel oxides outer layer and a Cr(OH)3 inner layer, and the oxide films inside the crevice consisted of a α-CrOOH outer layer and a Cr(OH)3 inner layer. When crevice corrosion occurred, the hydrolysis of Cr3+ led to the formation of Cr(OH)3 inside the crevice, and caused the pH value of crevice solution to decrease, and Cl− migrated from outside the crevice into inside the crevice due to electrical neutrality principle and accumulation. When the water chemistry inside the crevice reached the critical value of active dissolution of metal, the active dissolution of metal inside the crevice occurred. In addition, (Ni,Fe)(Fe,Cr)2O4 spinel oxides on the crevice mouth were formed by the deposition of metal ions migrated from inside the crevice. The mechanism of crevice corrosion and the formation mechanism of oxide films at different regions were also discussed.

Revealing the mechanism of electrochromic sticking image behavior in tungsten oxide film prepared from tungstate precursors

Ammonium tungstate precursor system are one of promising preparation routes for sol-gel tungsten oxide (WO3) film because of its low-cost preparation, good solution stability, and good solvent compatibility. Nevertheless, we notice that an incomplete ion extraction (called electrochromic sticking image) behavior of electrochromic WO3 film prepared from tungstate precursor, which weakens its electrochromic performance. In this work, some key factors such as residual precursor ammonium ions and oxygen vacancy defects are investigated to understand the electrochromic sticking image behaviors. For the amorphous WO3 film, the film components consist of WO3 and tungstate. The endogenic ammonium ions can preferentially participate in the coloring process to occupy the WO3 lattices. However, in the bleaching process, there is always part of ions remaining in the film due to electrical neutrality principle (between tungstate anions and positive ions), resulting in the electrochromic sticking image. For the crystalline WO3 film, the increasing concentration of oxygen vacancy and film density become a main factor that inhibits the extraction of Li+ ions, which is reflected by the low diffusion coefficient and high charge transfer resistance. For this case, a long-term bleaching bias is valid to eliminate the electrochromic sticking images for crystalline WO3 film. This work provides a mechanism understanding for improving the electrochromic memory of sol-gel WO3 film.