Transfer Resistance Values Research Articles

CeO2/PANI/MoS2 composite electrode for symmetric supercapacitor application

This work presents, the synthesized CeO2/PANI/MoS2 tri-composite performance as a symmetric electrode material for supercapacitor application. Analysis of XRD and FTIR was performed on the synthesized materials to investigate their crystalline structure and functional groups. The tri-composite SEM morphology shows a sheet-like structure covered with aggregated cerium and polyaniline nanoparticles. The electrochemical performances of the composite were done using the two-electrode symmetric system in 0.5 M of H2SO4. The resultant specific capacitance from the cyclic voltammetry was 177 F/g at 5 mV/s and from galvanostatic charge-discharge was 62 F/g at 0.5 current density. At 5 A/g, the composite demonstrated 98% capacitance retention after 2000 cycles. The impedance of the electrode materials was studied using electrochemical impedance spectroscopy. The tri-composite's solution resistance and transfer resistance values were 3.09 Ω and 0.51 Ω respectively.

Hydrothermally prepared nickel disulphide nanoparticles with enhanced areal capacitance

In this study, mesoporous nickel disulphide (NiS2) nano-particles have been successfully prepared using hydrothermal method. Phase formation and functional groups were identified by the high-resolution X-ray diffractometer (HR-XRD) and Fourier transform infrared spectroscopy (FTIR), respectively. Energy band gap of prepared NiS2 nanoparticles has been studied by diffuse reflectance spectroscopy. FESEM and N2 adsorption–desorption analysis affirmed that surface of the NiS2 nanoparticles is rough with large pore diameter 6.46 nm. Electro-catalytic properties of NiS2 have been analysed by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry technique in 1 M aqueous LiOH electrolyte. Electrochemical characterization affirmed that NiS2 has minimum charge transfer resistance (Rct) value of 3.84 Ω with enhanced areal capacitance 9.23 F cm−2 which showed 87% cyclic stability.

Influence of Metformin Hydrochloride- 250 mg (MFH) tablet on Corrosion Resistance of orthodontic wire made of NiCr alloy in Artificial Saliva

The corrosion resistance of orthodontic wire made of NiCr alloy in artificial saliva, in the absence and presence of Metformin Hydrochloride- 250 mg (MFH) has been evaluated by polarization study and AC impedance spectra. Polarisation study reveals that in the presence of Metformin Hydrochloride- 250 mg (MFH), linear polarisation resistance (LPR) value increases and corrosion current decreases. That is, in presence of Metformin Hydrochloride250 mg (MFH), the corrosion resistance of NiCr alloy in artificial saliva increases. AC impedance study reveals that in the presence of Metformin Hydrochloride- 250 mg (MFH), Charge transfer resistance (Rt) value increases and double layer capacitance value (Cdl) decreases. That is in the presence of Metformin Hydrochloride- 250mg (MFH) the corrosion resistance of NiCr alloy in AS increases. It is concluded that people clipped with orthodontic wire made of NiCr alloy need not vacillate to take Metformin Hydrochloride- 250 mg (MFH) orally. Keywords: Artificial Saliva; Corrosion; Metformin Hydrochloride- 250 mg (MFH); Orthodontic Wires; NiCr Alloy; Electrochemical Studies

Frequency Response Analysis of a Nonstationary System: Electrochemical Transition of Polyaniline

In this work, impedance spectra of polyaniline film electrode recorded at some redox transition potentials have been corrected for nonstationarity by application of Stoynov's 4-D method. The procedure consisted from: a) conventional measurements of a series of impedance spectra under strictly same experimental conditions, which are accompanied by monitoring of real operating time intervals for measurement of each particular impedance spectrum of the series, b) determination of functional dependence(s) between iso-frequency impedance values and operating time, and c) calculations of instantaneous IS for the time instant of the beginning of the first IS measurement. Comparison between measured and instantaneous impedance spectra, and also between their individual impedance parameter values pointed toward significant differences in charge transfer and transport resistance values. The results suggest that erroneous (either underestimated or overestimated) charge transfer and transport resistance values will be obtained if measured impedance spectra were not corrected for nonstationarity.

A novel hybrid composite coating of poly-3-amino-5-mercapto-1,2,4-triazole/TiO2 on copper for corrosion protection

Poly-3-amino-5-mercapto-1,2,4-triazole/TiO2 (p-AMTA/TiO2) composite was effectively synthesized over the copper surface by cyclic voltammetric technique and used as a protective coating against corrosion. The resulting polymeric composite was characterized using Fourier transform infrared spectroscopy. The presence of TiO2 particles in the polymer matrix was substantiated from X-ray diffraction pattern and energy-dispersive X-ray spectrum. The uniform dispersion of TiO2 particles in the polymeric matrix was confirmed by the scanning electron microscope images. The protective effect of composite coating was evaluated by electrochemical impedance spectroscopy and potentiodynamic polarization methods in 3.5 % NaCl medium. Impedance measurements showed that charge transfer resistance (Rct) values increased for polymeric composites which suggested the enhanced corrosion protection of copper. Further, the decrease in corrosion current density (icorr) values and shifting of corrosion potential (Ecorr) toward the cathodic direction confirmed the anticorrosive behavior of the polymeric composite. The reason for the higher protection of polymeric composite may be due to the well-dispersed TiO2 particles in the polymer matrix exhibiting the enhanced barrier properties to protect copper surface from corrosion. The defects in the coatings can be reduced by embedded TiO2 particles in the pores of the polymeric films to enhance the corrosion protection, consequently.

Effect of a deposition container on the nanostructural growth and DSSC application of rutile TiO2

Various rutile TiO2 nanostructures were grown using a wet chemical deposition method within plastic, glass, stainless-steel, copper, silver, etc., containers and their application in DSSCs was envisaged for the first time. The reaction rate is different in different containers. The effect of container environment on the morphology and optical properties of rutile TiO2 was investigated and can be attributed to the presence of the respective container element in TiO2. The metals (copper, silver, iron, sodium, etc.) are confirmed (in wt%) in the final products. Due to a change in the morphology followed by absorbance, the power conversion and incident photon-to-electron conversion efficiencies are different (higher in the copper container at 1.97% and 16%, and lower in the stainless-steel container at 0.26% and 3%, respectively). This change in performance can be attributed to a difference in the electron life time values, which are consistent with the charge transfer and series resistance values obtained from Nyquist plots.

Effects of Propargyl Alcohol on Electrochemical Behaviors of AZ91 Magnesium Alloy Anode in 3.5% NaCl Solution

To improve corrosion rates and activation properties of AZ91 magnesium alloy anode, effects of additives (propargyl alcohol) on electrochemical behaviors of AZ91 magnesium alloy in 3.5% NaCl solution have been examined by studying corrosion rate, polarization, open circuit potential (Eocp) and transfer resistance values (Rt) of electrochemical impedance spectroscopy(EIS). The results show that propargyl alcohol not only decreases corrosion rate of AZ91 magnesium alloy anode, corrosion-inhibition ratio is 64.6%, but also increases activation properties of AZ91 when 1.0 % propargyl alcohol added into 3.5% NaCl solution. The current density of AZ91 reaches 9.46 mA.cm-2 at-1.35V. Its active potential (Eact ) is-1.527 V , and Eocp is-1.556 V.

Electrochemical Behaviors of Different Gradesof Pure Aluminum in Alkaline Solution

Effects of impurity (Fe, Si, Cu), temperature and Na2SnO3 on anodic behaviors of various grades of pure aluminum namely Al-1(99.999%),Al-2(99.99%),Al-3(99.82%) and Al-4(99.5%) in 4mol/L KOH solution have been examined by studying corrosion rate, polarization , open circuit potential (OCP, or Eocp), discharge performance and transfer resistance values (Rt) of EIS. The results indicate that aluminum has higher activation and more severe corrosion with the temperature increase. When impurities (Fe, Si, Cu) content increases, aluminum has higher corrosion and achieving stationary open current potential (OCP) needs longer time. However, Al-3 has lower polarization and higher current density(400mA/cm2,at 1.224V) than others at 50 °C. Meanwhile, for Al-3, the stationary OCP is about 120 mV more negative at 50 °C than at 25 °C. In order to achieve the stationary OCPs and avoid the appearance of tin oxidation peak, 20min is suitable soaking time for Al in 5mmol/LNa2SnO3 +4mol/LKOH solution. The optimal electrochemical behaviors of Al including corrosion-resistance, activation , OCP and shorter delay time of electrode potential, have been achieved by adding 5mmol/L SnO32+ into 4mol/LKOH solution.