scholarly journals Hydrothermal Cobalt Doping of Titanium Dioxide Nanotubes towards Photoanode Activity Enhancement

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1507
Author(s):  
Mariusz Wtulich ◽  
Mariusz Szkoda ◽  
Grzegorz Gajowiec ◽  
Maria Gazda ◽  
Kacper Jurak ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Tio2 Nanotubes ◽  
Electrochemical Impedance ◽  
Visible Spectrum ◽  
Linear Sweep Voltammetry ◽  
Electrochemical Measurement ◽  
Flat Band ◽  
Light Illumination ◽  
Real Surface ◽  
Surface Area Increase

Doping and modification of TiO2 nanotubes were carried out using the hydrothermal method. The introduction of small amounts of cobalt (0.1 at %) into the structure of anatase caused an increase in the absorption of light in the visible spectrum, changes in the position of the flat band potential, a decrease in the threshold potential of water oxidation in the dark, and a significant increase in the anode photocurrent. The material was characterized by the SEM, EDX, and XRD methods, Raman spectroscopy, XPS, and UV-Vis reflectance measurements. Electrochemical measurement was used along with a number of electrochemical methods: chronoamperometry, electrochemical impedance spectroscopy, cyclic voltammetry, and linear sweep voltammetry in dark conditions and under solar light illumination. Improved photoelectrocatalytic activity of cobalt-doped TiO2 nanotubes is achieved mainly due to its regular nanostructure and real surface area increase, as well as improved visible light absorption for an appropriate dopant concentration.

scholarly journals Electrodeposition Kinetics of Ni/Nano-Y2O3 Composite Coatings

Metals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 669
Author(s):  
Xinyu Zhou ◽  
Yiyong Wang ◽  
Xianglin Liu ◽  
Zhipeng Liang ◽  
Hui Jin
Keyword(s):  
Electrochemical Impedance ◽  
Composite Coatings ◽  
Composite Films ◽  
Linear Sweep Voltammetry ◽  
Electrochemical Measurement ◽  
Charge Transfer Resistance ◽  
Solid Particles ◽  
Kinetics Parameters ◽  
Transfer Resistance ◽  
Composite Deposition

Ni/nano-Y2O3 composite films were successfully prepared by electrochemical deposition using an acid sulfamate bath. The influence of solid particles added to electrolyte on electrodeposition was investigated by electrochemical measurement methods. The linear sweep voltammetry test showed that the composite deposition took place at a greater potential than that of nickel, and the presence of nano-Y2O3 decreased cathodic polarization. Chronoamperometry studies indicated that the nucleation model of both deposits similarly approached the theoretical instantaneous nucleation mode based on the Scharifker–Hills model. The Y2O3 particles adsorbed on the cathodic surface were shown to facilitate the nucleation/growth of the nickel matrix which is consistent with the deposition kinetics parameters calculated by non-linear fitting experimental curves. The results of electrochemical impedance spectroscopy showed that the presence of Y2O3 particles in a bath is beneficial for the decrease in charge transfer resistance in the deposition. The atomic force microscopy observations of both deposits obtained in the initial electrodeposition stage confirmed that the Ni-Y2O3 composite had a higher grain number and finer mean grain size.

scholarly journals Silicon Carbide-Gated Nanofluidic Membrane for Active Control of Electrokinetic Ionic Transport

Membranes ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 535
Author(s):  
Antonia Silvestri ◽  
Nicola Di Trani ◽  
Giancarlo Canavese ◽  
Paolo Motto Ros ◽  
Leonardo Iannucci ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Silicon Carbide ◽  
Power Consumption ◽  
Low Power ◽  
Electrochemical Impedance ◽  
Field Effect Transistors ◽  
External Control ◽  
Low Power Consumption ◽  
Flat Band ◽  
Ionic Field

Manipulation of ions and molecules by external control at the nanoscale is highly relevant to biomedical applications. We report a biocompatible electrode-embedded nanofluidic channel membrane designed for electrofluidic applications such as ionic field-effect transistors for implantable drug-delivery systems. Our nanofluidic membrane includes a polysilicon electrode electrically isolated by amorphous silicon carbide (a-SiC). The nanochannel gating performance was experimentally investigated based on the current-voltage (I-V) characteristics, leakage current, and power consumption in potassium chloride (KCl) electrolyte. We observed significant modulation of ionic diffusive transport of both positively and negatively charged ions under physical confinement of nanochannels, with low power consumption. To study the physical mechanism associated with the gating performance, we performed electrochemical impedance spectroscopy. The results showed that the flat band voltage and density of states were significantly low. In light of its remarkable performance in terms of ionic modulation and low power consumption, this new biocompatible nanofluidic membrane could lead to a new class of silicon implantable nanofluidic systems for tunable drug delivery and personalized medicine.

scholarly journals Water Photo-Electrooxidation Using Mats of TiO2 Nanorods, Surface Sensitized by a Metal–Organic Framework of Nickel and 1,2-Benzene Dicarboxylic Acid

Hydrogen ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 58-75
Author(s):  
Sheng-Mu You ◽  
Waleed M. A. El Rouby ◽  
Loïc Assaud ◽  
Ruey-An Doong ◽  
Pierre Millet
Keyword(s):  
Dicarboxylic Acid ◽  
Electrochemical Impedance ◽  
Metal Organic Framework ◽  
Linear Sweep Voltammetry ◽  
Tio2 Nanorods ◽  
Tem Analysis ◽  
Vis Spectroscopy ◽  
Metal Organic ◽  
Benzene Dicarboxylic Acid ◽  
Organic Framework

Photoanodes comprising a transparent glass substrate coated with a thin conductive film of fluorine-doped tin oxide (FTO) and a thin layer of a photoactive phase have been fabricated and tested with regard to the photo-electro-oxidation of water into molecular oxygen. The photoactive layer was made of a mat of TiO2 nanorods (TDNRs) of micrometric thickness. Individual nanorods were successfully photosensitized with nanoparticles of a metal–organic framework (MOF) of nickel and 1,2-benzene dicarboxylic acid (BDCA). Detailed microstructural information was obtained from SEM and TEM analysis. The chemical composition of the active layer was determined by XRD, XPS and FTIR analysis. Optical properties were determined by UV–Vis spectroscopy. The water photooxidation activity was evaluated by linear sweep voltammetry and the robustness was assessed by chrono-amperometry. The OER (oxygen evolution reaction) photo-activity of these photoelectrodes was found to be directly related to the amount of MOF deposited on the TiO2 nanorods, and was therefore maximized by adjusting the MOF content. The microscopic reaction mechanism which controls the photoactivity of these photoelectrodes was analyzed by photo-electrochemical impedance spectroscopy. Microscopic rate parameters are reported. These results contribute to the development and characterization of MOF-sensitized OER photoanodes.

scholarly journals Deciphering the Disaggregation Mechanism of Amyloid Beta Aggregate by 4-(2-Hydroxyethyl)-1-Piperazinepropanesulfonic Acid Using Electrochemical Impedance Spectroscopy

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 788
Author(s):  
Hien T. Ngoc Le ◽  
Sungbo Cho
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Electrochemical Impedance ◽  
Specific Binding ◽  
Amyloid Β ◽  
Electrochemical Measurement ◽  
Charge Transfer Resistance ◽  
Chemical Agent ◽  
Transfer Resistance ◽  
K Value

Aggregation of amyloid-β (aβ) peptides into toxic oligomers, fibrils, and plaques is central in the molecular pathogenesis of Alzheimer’s disease (AD) and is the primary focus of AD diagnostics. Disaggregation or elimination of toxic aβ aggregates in patients is important for delaying the progression of neurodegenerative disorders in AD. Recently, 4-(2-hydroxyethyl)-1-piperazinepropanesulfonic acid (EPPS) was introduced as a chemical agent that binds with toxic aβ aggregates and transforms them into monomers to reduce the negative effects of aβ aggregates in the brain. However, the mechanism of aβ disaggregation by EPPS has not yet been completely clarified. In this study, an electrochemical impedimetric immunosensor for aβ diagnostics was developed by immobilizing a specific anti-amyloid-β (aβ) antibody onto a self-assembled monolayer functionalized with a new interdigitated chain-shaped electrode (anti-aβ/SAM/ICE). To investigate the ability of EPPS in recognizing AD by extricating aβ aggregation, commercially available aβ aggregates (aβagg) were used. Electrochemical impedance spectroscopy was used to probe the changes in charge transfer resistance (Rct) of the immunosensor after the specific binding of biosensor with aβagg. The subsequent incubation of the aβagg complex with a specific concentration of EPPS at different time intervals divulged AD progression. The decline in the Rct of the immunosensor started at 10 min of EPPS incubation and continued to decrease gradually from 20 min, indicating that the accumulation of aβagg on the surface of the anti-aβ/SAM/ICE sensor has been extricated. Here, the kinetic disaggregation rate k value of aβagg was found to be 0.038. This innovative study using electrochemical measurement to investigate the mechanism of aβagg disaggregation by EPPS could provide a new perspective in monitoring the disaggregation periods of aβagg from oligomeric to monomeric form, and then support for the prediction and handling AD symptoms at different stages after treatment by a drug, EPPS.

scholarly journals From Waste to Valuable Resource: Lignin as a Sustainable Anti-Corrosion Coating

Coatings ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 454 ◽  
Author(s):  
Arman Dastpak ◽  
Kirsi Yliniemi ◽  
Mariana de Oliveira Monteiro ◽  
Sarah Höhn ◽  
Sannakaisa Virtanen ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Open Circuit Potential ◽  
Electrochemical Impedance ◽  
Steel Corrosion ◽  
Linear Sweep Voltammetry ◽  
Corrosion Current ◽  
Polymer Coatings ◽  
Open Circuit ◽  
Linear Sweep ◽  
Cyclic Potentiodynamic Polarization

In this study, a waste of biorefinery—lignin—is investigated as an anticorrosion coating on stainless steel. Corrosion behavior of two lignin types (hardwood beech and softwood spruce) was studied by electrochemical measurements (linear sweep voltammetry, open circuit potential, potentiostatic polarization, cyclic potentiodynamic polarization, and electrochemical impedance measurements) during exposure to simulated body fluid (SBF) or phosphate buffer (PBS). Results from linear sweep voltammetry of lignin-coated samples, in particular, demonstrated a reduction in corrosion current density between 1 and 3 orders of magnitude cf. blank stainless steel. Furthermore, results from cross cut adhesion tests on lignin-coated samples demonstrated that the best possible adhesion (grade 0) of ISO 2409 standard was achieved for the investigated novel coatings. Such findings suggest that lignin materials could transform the field of organic coatings towards more sustainable alternatives by replacing non-renewable polymer coatings.

scholarly journals Photo-electrochemical Characterization of New Lead-free Ferroelectric Ba0.975Ho0.017(Zr0.2Ti0.75)Sn0.05O3) Ceramic. Application to Bezacryl Oxidation Under Solar Light

2021 ◽  
Author(s):  
S. Smail ◽  
Gharib Rekhila ◽  
K. Taïbi ◽  
A. Lahmar ◽  
M. Trari
Keyword(s):  
Electrochemical Impedance ◽  
Bulk Material ◽  
Rietveld Method ◽  
Solar Light ◽  
Flat Band ◽  
Oh Radicals ◽  
Dielectric Study ◽  
Relaxor Behavior ◽  
Order Kinetic ◽  
Electronic Density

Abstract Ba0.975Ho0.017(Zr0.20Ti0.75)Sn0.05O3 (abbreviated BHZ20TS) was elaborated by solid-state reaction at high temperature. The X-ray diffraction pattern, refined by the Rietveld method, indicated that the ceramic has a perovskite structure with a cubic symmetry. The Scanning electron microscopy revealed a high density and low porosity with reduced particle sizes upon substitution ofBa2+ by the rare earth ion Ho3+. The dielectric study as a function of temperature (-150 – 200 °C) and frequency (102 - 106 Hz) showed relaxor ferroelectric behavior. The modified Curie-Weiss law allowed us to evaluate the diffuse phase transition parameters. BHZ20TS obeys the empirical Vogel–Fulcher relation which confirms the relaxor behavior of this composition. With an optical band gap of 2.56 eV, BHZ20TS is attractive for photocatalytic applications. The capacitance-potential (C-2 - E) characteristic plotted in Na2SO4 (0.1 M) indicates n type behavior with a flat band potential (Efb) of -0.60 VSCE and electronic density (NA) of 2.2×1016cm-3. The semicircle in the Electrochemical Impedance Spectroscopy (EIS) measured in the range (10-3 – 105 Hz) is ascribed to the bulk material BHZ20TS (80 kW cm2) with a constant phase element (CPE) and a depletion angle of -5°. As application, the oxide was tested with success for the photooxidation under solar light of Bezacryl (BEZ), a hazardous dye. The energy band diagram shows an electron transfer from the conduction band of BHZ20TS to dissolved oxygen, generating O2· and OH·- radicals, responsible of the BEZ mineralization whose disappearance was followed by UV-Vis spectrophotometry. An abatement of 60% is obtained in BEZ solution (10 mg L-1) within 100 min under a solar irradiance of 97 mWcm-2; the mineralization obeys a first order kinetic model with a half photocatalytic life of 57 min.

scholarly journals Electrochemical Study of Copper Ferrite as a Catalyst for CO2 Photoelectrochemical Reduction

2018 ◽  
Vol 13 (2) ◽  
pp. 236 ◽  
Author(s):  
Kaykobad Md. Rezaul Karim ◽  
Huei Ruey Ong ◽  
Hamidah Abdullah ◽  
Abu Yousuf ◽  
Chin Kui Cheng ◽  
...  
Keyword(s):  
Sol Gel ◽  
Co2 Reduction ◽  
Linear Sweep Voltammetry ◽  
Band Gap Energy ◽  
Reduction Reaction ◽  
Electrochemical Study ◽  
Flat Band ◽  
Copper Ferrite ◽  
Onset Potential ◽  
P Type

In this work, p-type CuFe2O4 was synthesized by sol gel method. The prepared CuFe2O4 was used as photocathode catalyst for photoelectrochemical (PEC) CO2 reduction. The XRD, UV-Visible Spectroscopy (UV-Vis), and Mott-Schottky (MS) experiments were done to characterize the catalyst. Linear sweep voltammetry (LSV) was employed to evaluate the visible light (λ>400 nm) effect of this catalyst for CO2 reduction.  The band gap energy of the catalyst was calculated from the UV-Vis and was found 1.30 eV. Flat band potential of the prepared CuFe2O4 was also calculated and found 0.27 V versus Ag/AgCl. Under light irradiation in the CO2-saturated NaHCO3 solution, a remarkable current development associated with CO2 reduction was found during LSV for the prepared electrode from onset potential -0.89 V with a peak current emerged at -1.01 V (vs Ag/AgCl) representing the occurrence of CO2 reduction reaction. In addition, the mechanism of PEC was proposed for the photocathode where the necessity of a bias potential in the range of 0.27 to ~ -1.0 V vs Ag/AgCl was identified which could effectively inhibit the electron-hole (e-/h+) recombination process leading to an enhancement of CO2 reduction reactions. Copyright © 2018 BCREC Group. All rights reservedReceived: 4th July 2017; Revised: 5th November 2017; Accepted: 15th November 2017; Available online: 11st June 2018; Published regularly: 1st August 2018How to Cite: Karim, K.M.R., Ong, H.R., Abdullah, H., Yousuf, A., Cheng, C.K., Khan, M.K.R. (2018). Electrochemical Study of Copper Ferrite as a Catalyst for CO2 Photoelectrochemical Reduction. Bulletin of Chemical Reaction Engineering & Catalysis, 13 (2): 236-244 (doi:10.9767/bcrec.13.2.1317.236-244) 

scholarly journals Salt Concentration Effect on Electrical and Dielectric Properties of Solid Polymer Electrolytes based Carboxymethyl Cellulose for Lithium-ion Batteries

2021 ◽  
Vol 12 (5) ◽  
pp. 6114-6123
Keyword(s):  
Dielectric Properties ◽  
Ionic Conductivity ◽  
Polymer Electrolytes ◽  
Carboxymethyl Cellulose ◽  
Electrochemical Impedance ◽  
Lithium Ion ◽  
Lithium Perchlorate ◽  
Linear Sweep Voltammetry ◽  
Solid Polymer Electrolytes ◽  
Solid Polymer

Solid polymer electrolytes (SPEs) based carboxymethyl cellulose (CMC) with lithium perchlorate (LiClO4) were prepared via solution drop-cast technique. The CMC host is complexed by different concentrations of LiClO4 salt. SPEs were characterized by Electrochemical Impedance Spectroscopy (EIS) and Linear Sweep Voltammetry (LSV) in coin cells with lithium metal electrodes. EIS performed unique results based on various ionic conductivity values and dielectric properties. The higher ionic conductivity (1.32 × 10-5 S/cm) was obtained by SPEs 2 following by short-range ionic transport results based on dielectric properties depending on frequency. SPEs with LiClO4 addition are electrochemically stable over 2 V in lithium battery coin cells from LSV results.

scholarly journals Effects of Growth Temperature on the Physicochemical and Photoelectrochemical Properties of a Modified Chemical Bath Deposited Fe2O3 Photoelectrode

2020 ◽  
Vol 58 (4) ◽  
pp. 263-271
Author(s):  
Yaejin Hong ◽  
Seung-Hwan Jeon ◽  
Hyukhyun Ryu ◽  
Won-Jae Lee
Keyword(s):  
Thin Film ◽  
Film Thickness ◽  
Growth Temperature ◽  
Electrochemical Impedance ◽  
Ph Value ◽  
Saturated Calomel Electrode ◽  
Precursor Solution ◽  
Photocurrent Density ◽  
Flat Band ◽  
Photoelectrochemical Properties

In this study, Fe2O3 photoelectrode thin films were grown on fluorine-doped tin oxide substrates at various temperatures ranging from 145 to 220 oC using modified chemical bath deposition. The morphological, structural, electrical, and photoelectrochemical properties of the resulting Fe2O3 photoelectrode were analyzed using field emission scanning electron microscopy, X-ray diffraction, electrochemical impedance spectroscopy, and a three-electrode potentiostat/galvanostat, respectively. Growth temperature and hydrochloric acid etching both affected the growth of the Fe2O3 photoelectrode, with Fe2O3 thin film thickness first increasing and then decreasing as growth temperature increased. The pH value of the precursor solution varied according to growth temperature, which in turn affected film thickness. The highest photocurrent density (0.53 mA/cm2 at 0.5 V vs. saturated calomel electrode) was obtained from the Fe2O3 photoelectrode grown at 190 oC, which yielded the thickest thin film, smallest full width at half maximum and largest grain size for the (104) and (110) plane, and highest flat-band potential value. Based on these findings, the photoelectrochemical properties of Fe2O3 photoelectrodes grown at various temperatures are strongly affected by their morphological, structural, and electrical properties.

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