Oxide Chloride Research Articles

Partially selenized FeCo layered double hydroxide as bifunctional electrocatalyst for efficient and stable alkaline (sea)water splitting

Seawater electrolysis to produce hydrogen is a clean and sustainable strategy for the development of clean and sustainable energy storage systems. However, the erosion and destruction of electrocatalysts of the devices by Cl− in seawater during splitting process make it very difficult to realize. In this work, a partially selenized FeCo layered double hydroxide (Se-FeCo-LDH) catalyst is successfully synthesized, which shows good electrocatalytic performance in seawater during water splitting due to both its excellent conductivity and large surface area. Moreover, an anion aggregation layer around the electrode during the catalytic process can be formed to avoid electrode erosion and destruction by Cl− as well as the competitive reaction of chloride oxidation with the oxygen evolution reaction (OER), which not only improves the catalytic efficiency but also the durability of the catalyst. As a result, the overpotential is only 229 mV at a current density of 100 mA cm−2 for OER in 1 M KOH. Only 1.446 V and 1.491 V voltages are required to reach a current density of 10 mA cm−2 in overall alkaline water and seawater splitting, respectively. Besides, this Se-FeCo-LDH catalyst also achieves long-term stability up to 245 h in overall alkaline seawater splitting. The development of Se-FeCo-LDH catalyst should have an enlightening effect in the field of hydrogen production by (sea)water electrolysis.

A Reflection on Sustainable Anode Materials for Electrochemical Chloride Oxidation.

Chloride oxidation is a key industrial electrochemical process in chlorine-based chemical production and water treatment. Over the past few decades, dimensionally stable anodes (DSAs) consisting of RuO2 - and IrO2 -based mixed-metal oxides have been successfully commercialized in the electrochemical chloride oxidation industry. For a sustainable supply of anode materials, considerable efforts both from the scientific and industrial aspects for developing earth-abundant-metal-based electrocatalysts have been made. This review first describes the history of commercial DSA fabrication and strategies to improve their efficiency and stability. Important features related to the electrocatalytic performance for chloride oxidation and reaction mechanism are then summarized. From the perspective of sustainability, recent progress in the design and fabrication of noble-metal-free anode materials, as well as methods for evaluating the industrialization of novel electrocatalysts, are highlighted. Finally, future directions for developing highly efficient and stable electrocatalysts for industrial chloride oxidation are proposed.

Carrier Trap Density Reduction at SiO2/4H-Silicon Carbide Interface with Annealing Processes in Phosphoryl Chloride and Nitride Oxide Atmospheres.

The electrical and physical properties of the SiC/SiO2 interfaces are critical for the reliability and performance of SiC-based MOSFETs. Optimizing the oxidation and post-oxidation processes is the most promising method of improving oxide quality, channel mobility, and thus the series resistance of the MOSFET. In this work, we analyze the effects of the POCl3 annealing and NO annealing processes on the electrical properties of metal-oxide-semiconductor (MOS) devices formed on 4H-SiC (0001). It is shown that combined annealing processes can result in both low interface trap density (Dit), which is crucial for oxide application in SiC power electronics, and high dielectric breakdown voltage comparable with those obtained via thermal oxidation in pure O2. Comparative results of non-annealed, NO-annealed, and POCl3-annealed oxide-semiconductor structures are shown. POCl3 annealing reduces the interface state density more effectively than the well-established NO annealing processes. The result of 2 × 1011 cm-2 for the interface trap density was attained for a sequence of the two-step annealing process in POCl3 and next in NO atmospheres. The obtained values Dit are comparable to the best results for the SiO2/4H-SiC structures recognized in the literature, while the dielectric critical field was measured at a level ≥9 MVcm-1 with low leakage currents at high fields. Dielectrics, which were developed in this study, have been used to fabricate the 4H-SiC MOSFET transistors successfully.

It is not always chlorhexidine: Identification of benzoxonium chloride and lauramine oxide as culprit allergens in a popular antiseptic in Switzerland.

A popular antiseptic spray in Switzerland (Merfen spray), containing chlorhexidine digluconate, benzoxonium chloride and lauramine oxide, is frequently used to treat skin wounds. However, it is also increasingly reported as a major cause of adverse skin reactions, including allergic contact dermatitis (ACD). To investigate the contact allergens responsible for ACD from this antiseptic. Patch tests were performed on seven patients with a clinical history compatible with contact dermatitis from this antiseptic mixture. All patients presented with acute eczematous reactions following contact with either Merfen spray alone, or with multiple products including this spray. Patients showed positive reactions to this product in both patch tests and repeated open application tests (ROATs). Four patients showed dose-dependent reactions to both benzoxonium chloride and lauramine oxide. One patient showed a dose-dependent reaction to the former and a non-dose-dependent reaction to the latter. Finally, two subjects showed responses only to lauramine oxide. One patient reacted to chlorhexidine digluconate 0.5% aq. in addition to both other allergens. Two commercially unavailable allergens, that is, benzoxonium chloride and/or lauramine oxide were identified as major causes of ACD from Merfen antiseptic spray, whereas chlorhexidine digluconate was a contributing culprit in only one patient.

Atomic-Layer-Deposited TiO2–IrOX Nanoscale Thin-Film Electrocatalysts for Water and Chloride Oxidation: Influence of Local Phase Separation

TiO2–IrOX alloys with a range of compositions synthesized by atomic layer deposition (ALD) were configured as anodes for water and chloride oxidation. The effects of the alloys’ average composition on oxygen evolution reaction (OER) and chloride evolution reaction (CER) activity were investigated and correlated with their nanoscale structures and electrical transport properties. A higher electronic conductivity and superior electrochemical performance were obtained for the TiO2–IrOX alloy films with 38% iridium in comparison with alloy films of either lower or higher IrOX content. This composition exhibits the lowest activation overpotentials and Tafel slopes for both the OER and CER of the alloy compositions investigated with values for the CER approaching those of IrOX (no TiO2 component present). The 38% Ir composition also exhibits the largest photovoltage, that is, 650 mV, during water oxidation experiments on TiO2–IrOX alloy/n-silicon Schottky photoanodes. The composition dependence of (photo)electrocatalyst properties is found to correlate with observed trends for phase separation of the alloys into locally TiO2- and IrO2-rich regions. Conductive atomic force microscopy and chemical mapping using energy dispersive X-ray spectroscopy in scanning transmission electron microscopy indicate greater phase separation for the 38% IrOX composition than for the others synthesized.

Effect of NaCl-rich environment on internal corrosion for Ti60 alloy at 600 °C

The morphologies and compositions of internal oxides on Ti60 alloy after corrosion under solid NaCl in H2O+O2 at 600 °C have been studied by TEM. The results show that microstructure has an effect on the internal corrosion process. The partial pressure of Cl2 was found to be higher inside the β strip and at the β phase/α platelet boundary, which promotes the corrosion process in αs grains located inside the β strip. Our results confirm that the internal oxides do not originate from the oxidation of chlorides. Titanium depletion caused by the Cl attack promotes oxidation of the matrix.

Mn-Zr composite oxides for catalytic vinyl chloride oxidation: The deactivation and mechanism study

Mn-Zr composite oxides for catalytic vinyl chloride oxidation: The deactivation and mechanism study

Synthesis, aging and antimicrobial tests of (di)acrylate composites

Abstract The synthesis and characteristics of composites based on bisphenol A diacrylate with the addition of 2-ethylhexyl acrylate, butyl acrylate, or methyl methacrylate were carried out. Benzethonium chloride and zinc oxide were used as special additives in amounts of 1, 2, and 5 % by weight of monomers. These are compounds that exhibit antimicrobial properties. The composites were produced by the UV polymerization method with the addition of Irgacure 651 as a photoinitiator. Aging and swelling tests were carried out in water, solutions of hydrochloric acid and sodium hydroxide, and acetone. To confirm the changes in the structure of the composites, ATR/FT-IR spectra were performed before and after the degradation process. The hardness of the composites was also tested. The antimicrobial properties against Escherichia coli, Staphylococcus aureus, Aspergillus niger, and Candida albicans were checked. The conducted study also showed the significant changes in the Cerrena unicolor fungus secretome caused by the presence of the composites.

Characterization and Superhydrophobic Anticorrosive Coating of AA-7475/ZrO2/Polymer Nanocomposites

An AA-7475 is coated with superhydrophobic (SH) polymer nanocomposites (PNCs), emphasizing the coating’s manufacturing, characterization, and anticorrosive qualities. Coating AA-7475 alloy with polyvinyl chloride (PVC), copper stearate (CS), and zirconium oxide (ZrO2) nanoparticles produces the desired superhydrophobic. Using an X-ray diffractometer, field-emission scanning electron microscopy, Fourier-transform infrared spectrometer, ZrO2 nanoparticles, CS, and PVC PNCs are analyzed structurally and molecularly. The atomic force microscope picture was analyzed to determine how the surface roughness affected the SH behavior reached by changing the weight percentage of ZrO2 nanoparticles from 0.6 to 3.0 wt%. PNC-5 with 3.0 wt% ZrO2 nanoparticles is used as resistance to corrosion coating for AA-7475 due to its water contact angle of 154°. In a 3.5% NaCl solution, uncoated and PNC-5-coated AA-7475 are examined using potentiodynamic polarization and electrochemical spectroscopy. PNC-5 coating reduces AA-7475 corrosion rate from 23.75 to 0.2253 mpy. In this study, we use polarization resistance, corrosion resistance efficiency, double layer capacitance, corrosion current density, and charge transfer resistance to demonstrate that the SH surface air trapping phenomena are responsible for effective corrosion resistance.

Design of High Sensitivity Cellulose Filter Paper-based SERS Flexible Substrate for Testing Harmful Rust of Bronze Ware

Surface-enhanced Raman scattering (SERS), a simple, highly sensitive, and fast analytical method can be used to detect corrosion components on the surface of bronze ware, a difficult problem. The silver mirror reaction is suggested for depositing precious metal nanoparticles on cellulose filter paper in order to create a quick, easy, and low-cost approach for creating SERS substrates. After an 8-minute deposition time, optical microscopy and scanning electron microscopy (SEM) revealed a uniform dispersion of precious metals on cellulose filter paper. To examine the SERS characteristics of the substrate, copper chloride oxide, the main ingredient in the damaging rust of trace bronze ware, was used as the probe molecule. The findings show that cellulose filter paper with a uniform distribution of precious metals achieves the best SERS performance. The flexible substrate enables effective trace analysis of damaging rust on bronze surfaces.

Effect of NaCl and SO2 on the stress corrosion cracking of CMSX-4 at 550°C

ABSTRACT In the pursuit of more efficient gas turbine engines, components are required to operate for longer times at elevated temperatures. This increased time in service, together with a complex loading regime, can expose the material to environmental attack. This work has demonstrated that the interaction of stress, NaCl and a sulphur-containing environment is critical to cause crack initiation in the early stages of the exposure and accelerated corrosion rates in CMSX-4 at 550°C. The effect of having small concentrations of moisture in the gaseous environment or as water crystallisation in the salt is still to be investigated. A working hypothesis is that the interaction of alkali chlorides with a sulphur-containing atmosphere is the trigger to a self-sustaining cycle where metal chloride formation, vaporisation and oxidation lead to high amounts of hydrogen injection in a rapid manner and, therefore, hydrogen embrittlement.

Nanorod Array-Based Hierarchical NiO Microspheres as a Bifunctional Electrocatalyst for a Selective and Corrosion-Resistance Seawater Photo/Electrolysis System

Utilizing earth-abundant seawater over scarce freshwater for hydrogen fuel production via water electrolysis is a promising/sustainable strategy. However, the serious anodic corrosion due to the competing chloride oxidation reaction significantly hampers the overall stability of the electrolyzer. Therefore, it demands an efficient and robust catalyst with high selectivity and corrosion resistance for direct seawater splitting. Here, we present a bifunctional catalyst developed by morphology engineering to form nanorod array-based hierarchical NiO microspheres (NRAHM-NiO) as a three-dimensional (3D) hierarchical oxide/hydroxide urchin-like structure material for highly selective seawater splitting against chloride oxidation. Benefitting from highly intrinsic electroactive sites, good charge transferability, fast-releasing gas bubbles, and corrosion resistance as well as hydrophilic surface, the NRAHM-NiO exhibits outstanding bifunctional hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) catalytic activity toward selective and durable overall seawater splitting. The system requires small cell voltages of 1.66 and 2.01 V to drive current densities of 100 and 500 mA cm–2 at room temperature, respectively. Such catalytic activity is superior compared to the benchmark Pt/C(−)||Pt/C(+) and Pt/C(−)||IrO2(+) pair systems. Importantly, this device demonstrates specific stability as well as selectivity toward the OER in seawater with 99% faradaic efficiency without forming any chlorine species. The experimental results are well supported by density functional theory (DFT) calculations. Powered by a single solar cell, the integrated photolysis system shows 9.9% solar-to-hydrogen (STH) efficiency.

Co3O4 hollow nanotubes for the catalytic oxidation of C2-chlorinated VOCs

Structured Co3O4 catalysts with a hollow nanotube morphology were prepared by several synthesis routes based on the Kirkendall effect. The resulting samples were kinetically evaluated in the gas-phase oxidation of vinyl chloride and 1,2-dichloroethane, two model C2-chlorinated volatile organic compounds; and exhaustively characterised by means of BET measurements, X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, thermogravimetry and temperature-programmed techniques (adsorption of ammonia and chlorinated VOC, O2-TPD, H2-TPR and TPO). The performance of the prepared nanotubes was essentially controlled by the presence of active oxygen species at the surface, which in turn depended on the Co2+/Co3+ molar ratio, and the adsorption capacity of the catalyst for the chlorocarbon. Both pollutants were efficiently converted to deep oxidation products at relatively low temperatures. In addition, the optimal catalyst exhibited an appreciable stability when operating during 120 h.

Synthesis and Characterization of Oxide Chloride Sr2VO3Cl, a Layered S = 1 Compound.

The mixed-anion compound with composition Sr2VO3Cl has been synthesized for the first time, using the conventional high-temperature solid-state synthesis technique in a closed silica ampule under inert conditions. This compound belongs to the known Sr2 TmO3Cl (Tm = Sc, Mn, Fe, Co, Ni) family, but with Tm = V. All homologues within this family can be described with the tetragonal space group P4/nmm (No. 129); from a Rietveld refinement of powder X-ray diffraction data on the Tm = V homologue, the unit cell parameters were determined to a = 3.95974(8) and c = 14.0660(4) Å, and the atomic parameters in the crystal structure could be estimated. The synthesized powder is black, implying that the compound is a semiconductor. The magnetic investigations suggest that Sr2VO3Cl is a paramagnet at high temperatures, exhibiting a μeff = 2.0 μB V-1 and antiferromagnetic (AFM) interactions between the magnetic vanadium spins (θCW = -50 K), in line with the V-O-V advantageous super-exchange paths in the V-O layers. Specific heat capacity studies indicate two small anomalies around 5 and 35 K, which however are not associated with long-range magnetic ordering. 35Cl ss-NMR investigations suggest a slow spin freezing below 4.2 K resulting in a glassy-like spin ground state.

Boosting vinyl chloride combustion over Pt/WOx/ZrO2: Regulating redox and acidity

Pt/WOx/ZrO2 were prepared and evaluated for vinyl chloride (VC) oxidation. Increasing WOx loading amount caused the evolvement of tungsten state and the augmentation in the total acid amount facilitating VC adsorption and Cl removal. The electron transfer between Pt and WOx regulated the Pt dispersion, chemical state and redox property. High ratio of active Pt species and oxygen species facilitated oxidation and avoided coke formation. Pt/8W/ZrO2 with 8 wt%WOx outperformed Pt/ZrO2, for its reaction rate was 7 times higher than that of Pt/ZrO2 and kept stable for 60 h. 90% VC conversion could be achieved at 195 ℃ with 2% water and negligent chlorinated by-products was detected during oxidation.

Hybrid Lead‐Free Metal Antimony Oxide Chlorides with Highly Efficient Blue Light Emissions

AbstractHerein, we report two hybrid zero‐dimensional (0D) lead‐free metal oxide halides of [PPip]Sb2Cl6O (1) ([PPip]=1‐(2‐Pyridyl)piperazine) and [PmPip]Sb2Cl6O (2) ([PmPip]=1‐(2‐Pyrimidyl)piperazine). Compounds 1 and 2 are able to exhibit narrow blue light emissions excited by UV light with photo‐luminescence quantum yields (PLQYs) of 25.49 % and 24.71 %, respectively. Through systematical characterizations, these blue light emissions can be attributed to the radiative transition in conjugated organic cations. Benefiting from the highly efficient intrinsic blue emissions, compound 2 can be used as blue fluorophor to fabricate liquid crystal display. This work provides a new to assembly blue emitter through by virtue of the optical active organic cations in hybrid materials.

Coupling Ferrocyanide-Assisted PW/PB Redox with Efficient Direct Seawater Electrolysis for Hydrogen Production

Direct seawater electrolysis is a promising approach for grid-scale hydrogen mass production. However, the low energy efficiency and detrimental anodic chlorine electrochemistry unlock its practical potential. Here, we present an efficient chlorine-free hydrogen production by coupling the rapid electrode reaction of ferrocyanide-assisted Prussian white (PW)/Prussian blue (PB) redox with an onset potential of 0.87 VRHE. The chloride oxidation in our cells is avoided by low cell voltages, enabling high-purity hydrogen production. Operando spectroscopic analysis coupled with theoretical calculations validates that the addition of the [Fe(CN)6]3–/4– redox mediator in the electrolyte can reduce the PB to PW instantaneously, thus completing the cycle of PW/PB redox and making the system recyclable. The assembled electrolyzer exhibited unprecedented performance for direct seawater electrolysis (pH = 8.5), achieving a current density of 320 mA cm–2 at 1.7 V. Therefore, the electricity consumed per cubic meter of H2 produced in the electrolyzer is 3.8 kWh at 200 mA cm–2, and 42% lower energy equivalent input relative to commercial redox-free seawater electrolysis. This work offers a cost-competitive and energy-saving strategy for producing high-purity H2 directly from unlimited seawater.

Hydrothermally synthesized titanium/hydroxyapatite as photoactive and antibacterial biomaterial

The present work investigated hydrothermal synthesis of titanium/hydroxyapatite (Ti/HA) nanocomposite at varied Ti content. The synthesis was performed by coprecipitation method using CaO, ammonium dihydrogen phosphate and titanium oxide chloride precursor with the additional cetyl trimethyl ammonium chloride as templating agent, followed by hydrothermal treatment at 150 °C. The derived materials were characterized by x-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy analyses. The photocatalytic properties of materials were tested on methyl violet (MV) photocatalytic oxidation, meanwhile the antibacterial testing was performed against Escherichia coli, Staphylococcus aureus, Klebsiella pneumonia, and Streptococcus pyogenes. In addition, cytotoxicity evaluation of the materials as potential biomaterial was also conducted. The results showed that physicochemical character of Ti/HA exhibits exhibit the excellent properties to be photocatalyst along with antibacterial activity. From the detail study of effect of varied titanium content ranging from 5 to 10 %wt., the increasing crystallite size of anatase phase of about 25.81 nm and 38.22 nm for Ti content of 5 and 10 % wt., respectively. In other side, the band gap energy value increases as the increasing Ti content, i.e. the values are 3.08; 3.18; and 3.20 eV for Ti content of 5, 10, 20 % wt., respectively. The band gap energy is correlated with the photocatalytic activity which the highest MV degradation was 96.46% over Ti/HA with 20% wt. of Ti (Ti20/HA). The nanocomposites also express the antibacterial activity with comparable minimum inhibitory concentration (MIC) with other similar Ti/HA nanocomposites. The MIC values of Ti20/HA against E. coli, S. aureus, K. pneumonia, and S. pyogenes are 25; 25; 50 and 50 μg/mL, respectively. In addition, the cytotoxicity test revealed the potency to be a biomimetic material as shown by severe toxicity.

Lead retardation on cement hydration: Inhibition and re-acceleration of clinker dissolution

Lead-bearing solid wastes strongly retard the hydration of Portland cement. In this work, the effect of Pb(NO3)2 and PbCl2 on the hydration of Portland cement and tricalcium silicate (C3S) was investigated. The results show that both Pb(NO3)2 and PbCl2 prominently delay the end of the dormant period, the setting time of cement paste, and decrease compressive strength especially at lead dosages of 1%. Conductivity, pH, and elemental concentration in C3S suspension underlined a strong effect of lead on C3S reaction kinetics. XRD and SEM-EDS measurements indicated the formation of lead silicates and chloride (hydr)oxides. Alite dissolution is probably retarded by the formation of surface complexes between Pb(II) with silanol groups on clinker surface. The increase of pH and precipitation of less soluble Pb-hydrates lowers Pb concentrations and the inhibition induced by Pb(II).

Barium carbonate promoted cobalt oxide as highly efficient catalyst for the total oxidation of vinyl chloride

Co-based catalyst has excellent chlorine resistance, so it is an effective catalyst to degrade VC at present. A series of high-performance CoxBa1 catalysts were prepared by doping Ba into Co3O4 and changing the Ba/Co mol ratio. Under the condition of space velocity of 15,000 ml·g−1·h−1, the conversion rate of VC reached 90% at 199 °C in Co19Ba1, the temperature is much lower than T90 of pure Co3O4 (309 °C), and the catalysis activity of Co19Ba1 was higher than that of the other alkali metal-doped Co19M1 (M = Sr, Ca). Ba species in CoxBa1 mainly exist in the form of BaCO3. With the addition of BaCO3, the particle size of CoxBa1 decreases, resulting in the increase of active site of CoxBa1. BaCO3 can also make CoxBa1 obtain better low-temperature reducibility and more active components. In addition, the increase of BaCO3 content will also increase the basic sites of CoxBa1, and more basic sites can effectively protect Co3O4 from Cl poisoning. When Ba/Co is 1/19, the content of BaCO3 is the highest, so Co19Ba1 also shows the best activity.