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Structure–Activity/Stability Correlations from the Electrochemical Dynamic Responses of Titanium Anode Coatings Formed of Ordered TiO <sub/>2</sub> @RuO <sub/>2</sub> Microspheres
摘要： Spherical TiO2/RuO2 particles were synthesized by ultrasonic spray pyrolysis (USP) at 200 and 800?C. The activity for the oxygen and chlorine evolution reactions (OER and CER, respectively) and the dynamic responses from electrochemical impedance spectroscopy (EIS) of the USP powders, as well as of the corresponding coatings on Ti, were analyzed and are discussed. The loss of coating activity is discussed with respect to the differences in the EIS and cyclic voltammetry responses of the coatings in their active and inactive states. The 800?C-USP sample was found to be more active than the 200?C-USP sample for both the CER and the OER, whereas the stability of the former was considerably lower. The correlation between the structure, composition and morphology of the powder and the coating with the registered electrochemical properties is discussed. The EIS analysis of the coating resistance distributions induced by the thermal treatment of the powder indicated a complex combination of the pore resistance and the pseudocapacitive charge transfer resistance. An additional coating resistance, due to loose grain boundaries, was introduced into the coatings in their active and inactive state. The EIS analysis indicated the changes in TiO2-enriched core/RuO2-enriched shell structure, caused by the USP temperature.
关键词： TiO2/RuO2,cyclic voltammetry,electrochemical impedance spectroscopy,oxygen evolution reaction,chlorine evolution reaction,ultrasonic spray pyrolysis,coating stability
更新于2025-09-11 14:15:04
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Synthesis of Functionalized Polythiophene as a Potenial Organic Semi-Conductor
摘要： The synthesis Poly[1,5-naphthyridine-(3-hexylthiophene)] (PN3HTh) semi-conducting polymer has been accomplished by adopting both conventional and microwave-assisted Suzuki-Miyaura cross-coupling reaction between 3-hexylthiophene-2,5-diboronic ester and 2,6-dibromo-1,5-naphthyridine. The electrochemical and transport properties of PN3HTh were investigated both in the bulk as well as in thin film form. These properties can be further tuned by changing the solvent and the nature of the electrode used. Consequently, cyclic voltammetry (CV) measurements were conducted using a potentiostat coupled with an electrochemical cell. The CV results of PN3HTh as a bulk form in H2SO4 solution indicated that the concentration of the polymer in the solution is not well defined because of polymer poor solubility in aqueous solutions. On the other hand, the sulfur group which works as electron donating makes the system more electron-rich. This can explain by the absence of the reduction peak. For the thin film, two single oxidation peaks were obtained at around 0 V and 0.3 V for both cases. Different solvents can tune the transport properties of the polymer as can be seen from the two CVs where BF3 exhibited enhanced transport properties over ACN. The synthesized polymers were characterized by modern spectroscopic methods including IR and NMR.
关键词： Suzuki-Miyaura cross-coupling,Cyclic Voltammetry,Electrochemical Properties,Organic Semiconductor,Polythiophene
更新于2025-09-11 14:15:04
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Some insights into the structure and morphology of surfactant-doped poly(o-toluidine)
摘要： Poly(o- toluidine) (POT) doped with dodecylbenzene sulfonic acid (DBSA) was synthesized by inverse emulsion polymerization and characterized systematically for morphological, structural, electrochemical, and thermal properties with scanning electron microscopy (SEM), cyclic voltammetry (CV), X- ray diffraction (XRD), and thermogravimetric analysis (TGA). SEM demonstrated irregular granular morphology of the polymer with high porosity similar to polyaniline (PANI). The size distribution of POT salts was analyzed using Nano Measurer 1.2.5 software from scanning electron micrographs. The semicrystalline nature, with crystallite size and d- spacing in the range of 21.4–30.2 nm and 4.93–4.99 ?, respectively, was confirmed from XRD. The activation energy (Ea) of degradation was calculated from TGA curves using Coats and Redfern (39.92–47.50 kJ/mol) & Horwitz and Metzger (50.09 ? 57.45 kJ/mol) methods, respectively. The small crystallite size, high thermal stability, and high values of the activation energy of degradation reveal that DBSA is an efficient dopant for POT and imparts interesting characteristics to this otherwise less thermally stable polymer. The fast rate of electron transfer of POT, as confirmed by electrochemical impedance spectroscopy, reveals its high electrochemical activity toward electrolyte. Potentiodynamic polarization measurement of POT- coated stainless steel showed large anodic potential shift as compared to uncoated stainless steel, illustrated good anticorrosion performance. The enhanced anticorrosion performance is due to synergic effect of dopant which increases the contortion of diffusion pathway of corrosive substance.
关键词： thermogravimetric analysis,cyclic voltammetry,stainless steel,poly(o-toluidine)-doped with dodecylbenzene sulfonic acid,X-ray diffraction,activation energy,anticorrosion
更新于2025-09-10 09:29:36
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Silicon-silver dendritic nanostructures for the enhanced photoelectrochemical splitting of natural water
摘要： We report on the photoelectrochemical (PEC) splitting of natural water (pH 7) using silicon (Si) nanowires fitted with silver (Ag) dendrites (dendritic nanostructures) as working electrodes (photoanodes). A detailed study of the PEC water splitting process was carried out using linear sweep voltammetry, electrochemical impedance spectroscopy (EIS) and Mott-Schottky (M-S) measurements. The measured photocurrent density of 1.7 mA/cm2 at an external voltage of ?0.6 V under white light illumination demonstrates the efficient decomposition of natural water using dendritic nanostructures as working electrodes. This decomposition is mainly attributed to a significant strengthening of the effective interface between working electrode surface/water and to a decline in the recombination of photoinduced carriers in the presence of Ag dendrites. We propose that the Schottky barrier between Si and Ag dendritic nanostructures favors enhanced photoinduced charge carrier separation. Photoinduced holes in Si are transferred to Ag dendrites (nano branches and leaves) that serve as a charge sink to effectively carry out the PEC oxidation of water. Photoinduced charge carrier separation enhancement was corroborated by the kinetics of our carrier recombination study. We obtained a reasonably long transient period of 80 s for the photoinduced carriers. EIS results show that the charge transfer resistance (150 Ω) of the dendritic nanostructure surface is low enough to promote interfacial charge transfer. This resistance generated a large carrier concentration of ~1.1 × 1020 cm?3 at the working electrode/water interface according to an M-S analysis. An applied bias-photon-to-current-conversion efficiency level of roughly 4% is reported, demonstrating the efficient PEC splitting of natural water.
关键词： Linear sweep voltammetry,Photoinduced charge carrier separation enhancement,Photoelectrochemical,Applied bias-photon-to-current-conversion efficiency,Ag dendrites
更新于2025-09-10 09:29:36
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Flakes Size-Dependent Optical and Electrochemical Properties of MoS2
摘要： Background: Molybdenum disulfide (MoS2) is a transition metal dichalcogenides and has some interesting and promising properties. MoS2 has direct and indirect band gaps depending on its crystalline structure. In addition, its sheets morphology makes it a good candidate for supercapacitor applications. Objective: The aim of this work is to study the effect of MoS2 flakes size on its optical and electrochemical properties. Method: MoS2 with different flakes sizes were prepared by exfoliation method. The exfoliation was performed by sonication of MoS2 powder in N,N-Dimethylformamide followed by different centrifugation speeds. UV-Vis spectra illustrated the optical energy gap was inversely proportional to the MoS2 flakes size. Results: Absorption coefficient values indicated that the exfoliation reduced the number of layers. Symmetric supercapacitor was made from two MoS2 electrodes and tested in 6 M KOH electrolyte. The specific capacitance was found to be dramatically increased with decreasing flakes size (9.5 and 4.5 mF/cm2 for 0.26 and 0.98 μm flakes size, respectively). Conclusion: These findings recommend that MoS2 can be the excellent electrode material for supercapacitor.
关键词： nanoflakes,cyclic voltammetry,supercapacitors,Transition Metal Dichalcogenides (TMDs),optical band gap,Molybdenum disulfide
更新于2025-09-10 09:29:36
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Synthesis and Electrochemical Characterization of AgNP Ink Suitable for Inkjet Printing
摘要： To meet the growing demand for inkjet printable nanoparticle-based conductive inks, novel synthetic approaches are needed. In this study, spherical silver nanoparticles (AgNPs) with a mean diameter of approximately 2.5 nm were synthesized by the reduction of silver nitrate using an aqueous hydrazine solution in the presence of poly(acrylic acid) as a capping agent. The main goal of this work was the implementation of cyclic voltammetry as an electrochemical method for studying both the absorption of poly(acrylic acid) on the grain surface and nanoparticle interactions. The same technique was used to determine equimolar additions of hydrazine to obtain a high yield of reduced silver. All solutions used in the experiments were prepared at a high molar concentration. Silver nanoparticle-based ink was prepared by dispersing dried nanoparticles into a mixture of water and ethylene glycol and was stable for over seven months. For a comprehensive study of the prepared nanoink, UV-visible and electronic microscopy measurements were carried out. An inkjet technology was applied to deposit conductive ink to form linear silver tracks on a flexible substrate. These tracks exhibited a resistivity of 8.0×10-8 ?m.
关键词： conductive ink,poly(acrylic acid),cyclic voltammetry,Inkjet printing,silver nanoparticles
更新于2025-09-09 09:28:46
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Extraordinary dielectric properties at heterojunctions of amorphous ferroelectrics
摘要： Materials having a high dielectric constant are needed for a variety of electrical applications from transistors to capacitors. Ferroelectric amorphous-oxide (glass) alkali-ion electrolytes of composition A2.99Ba0.005ClO (A = Li, Na) are shown by two different types of measurement and different consistent analysis to have extraordinarily high dielectric constants varying from 109 at 25°C to 1010 at 220°C if the glass is properly conditioned. These anomalously high dielectric properties coexist with alkali-ion conductivities at 25°C that are equivalent to those of the best organic-liquid electrolytes of a Li-ion cell, and cyclic voltammetry (CV) in a Au/glass electrolyte/Au cell is stable from ?10 to +10 V. A model to interpret microscopically all the key features of the CV curves shows that the electric-double-layer capacitors (EDLCs) that form at the gold/electrolyte interfaces in the Au/glass electrolyte/Au heterojunction reverse polarization at an applied voltage V = ± 2.1 V resulting in three almost equivalent discharging capacitances for a single physical capacitor from -10 to +10 V.
关键词： amorphous-oxide,ferroelectric,alkali-ion electrolytes,dielectric constant,electric-double-layer capacitors,cyclic voltammetry
更新于2025-09-09 09:28:46
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Incipient Anion Intercalation of HOPG Close to the Oxygen Evolution Potential. A Combined X-ray Photoemission and Raman Spectroscopy Study
摘要： In the present work we used two different electrochemical (EC) techniques, namely cyclic voltammetry (CV) and normal pulsed voltammetry (NPV), applied to a highly oriented pyrolytic graphite (HOPG) electrode for anion intercalation in two different aqueous electrolytes (i.e. perchloric and sulphuric acid). We performed comparative X-ray photoemission (XPS) and Raman spectroscopy studies at various EC potentials. The chemical analysis obtained by XPS and Raman, the latter applied in-situ and in real-time during the electrochemical processes, indicates that at oxygen evolution potential (i.e. before reaching the well-known intercalation stage potentials) the HOPG intercalation process is already active. These results suggest that the intercalated compound is efficiently obtained before reaching higher potentials, which usually cause a detriment of the graphite crystal.
关键词： HOPG,Raman spectroscopy,X-ray photoemission,anion intercalation,normal pulsed voltammetry,cyclic voltammetry
更新于2025-09-04 15:30:14
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Bis[1]benzothieno[1,4]thiazines - Planarity, Enhanced Redox Activity and Luminescence by Thieno-Expansion of Phenothiazine
摘要： Twofold Buchwald-Hartwig aminations selectively furnish all three regioisomers of bis[1]benzothieno[1,4]thiazines and X-ray structure analyses and DFT calculations were corroborated for correlation of their electronic properties. All regioisomers outscore the parent compound phenothiazine with respect to a low lying oxidation potential and reversible redox activity. The anti-anti bis[1]benzothieno[3,2-b:2',3'-e][1,4]thiazines possess lowest oxidation potentials in this series and display pronounced green luminescence in solution (?F ≈ 20%) and in the solid state. Syn-anti regioisomers are only weakly luminescent in solution, but show aggregation induced emission enhancement and solid state luminescence. Most interestingly, found by X-ray structure analyses anti-anti derivatives reveal an amazingly coplanar structure of the pentacyclic anellated 1,4-thiazine system, emphasizing a structural similarity to heteroacenes. The calculated theoretical nucleus-independent chemical shifts additionally suggest that the 8?-electron core systems can be considered as first electronically unbiased anellated 1,4-thiazines with antiaromatic character.
关键词： Heterocycles,1,4-Thiazines,Fluorescence,Buchwald-Hartwig coupling,Cyclic voltammetry,Absorption,Antiaromaticity,Aggregation induced emission enhancement,Polymorphism,DFT calculations
更新于2025-09-04 15:30:14
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A glassy carbon electrode modified with TiO2(200)-rGO hybrid nanosheets for aptamer based impedimetric determination of the prostate specific antigen
摘要： TiO2(200)-rGO hybrid nanosheets were synthesized starting from TiO2, rGO and NaOH solid powders via a scalable hydrothermal process. The weight ratio of TiO2-GO was found to be crucial on the crystal growth and biosensor properties of the final hybrid nanosheets. They were characterized by means of SEM, FESEM-EDX, XRD, XPS, Raman and FTIR spectroscopies in order to verify the formation of very thin TiO2 anatase nanosheets with an orientation of the anatase crystal structure towards the (200) plane. The free active sites of TiO2 structure and the large surface of the 2D graphene structure strongly facilitate charge transport confirmed by BET-BJH analyses. Compared to pure AuNPs, rGO and TiO2, the hybrid nanosheet modified electrode represents the most sensitive aptasensing platform for the determination of PSA. The detection was based on that the variation of electron transfer resistance (Rct) at the modified electrode surface in a solution containing 3.0 mmol L?1 [Fe(CN)6]3?/4- as a redox probe and 0.1 mol L?1 KCl as supporting electrolyte. The detection limit of the sensor is 1 pg mL?1, and the sensor can be operated up to 30 days. It was applied to the analysis of PSA levels in spiked serum samples obtained from patients with prostate cancer. Data compare well with those obtained by an immunoradiometric assay.
关键词： X-ray photoelectron spectroscopy,Effective surface area,Electrochemical impedance spectroscopy,Aptasensor,Voltammetry,Work function
更新于2025-09-04 15:30:14