scholarly journals Characterization of Pt-Pd/C Electrocatalyst for Methanol Oxidation in Alkaline Medium

2011 ◽  
Vol 2011 ◽  
pp. 1-16 ◽  
Author(s):  
S. S. Mahapatra ◽  
J. Datta
Keyword(s):  
Methanol Oxidation ◽  
Electrode Surface ◽  
Electrochemical Impedance ◽  
Physicochemical Characterization ◽  
Charge Transfer Resistance ◽  
Graphite Substrate ◽  
Peak Current Density ◽  
Transfer Resistance ◽  
Alloyed Surface

The Pt-Pd/C electrocatalyst was synthesized on graphite substrate by the electrochemical codeposition technique. The physicochemical characterization of the catalyst was done by SEM, XRD, and EDX. The electrochemical characterization of the Pt-Pd/C catalyst for methanol electro-oxidation was studied over a range of NaOH and methanol concentrations using cyclic voltammetry, quasisteady-state polarization, chronoamperometry, and electrochemical impedance spectroscopy. The activity of methanol oxidation increased with pH due to better OH species coverage on the electrode surface. At methanol concentration (>1.0 M), there is no change in the oxidation peak current density because of excess methanol at the electrode surface and/or depletion of OH−at the electrode surface. The Pt-Pd/C catalyst shows good stability and the low value of Tafel slope and charge transfer resistance. The enhanced electrocatalytic activity of the electrodes is ascribed to the synergistic effect of higher electrochemical surface area, preferred OH−adsorption, and ad-atom contribution on the alloyed surface.

scholarly journals Synthesis and Characterization of Electrodeposited C-PANI-Pd-Ni Composite Electrocatalyst for Methanol Oxidation

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
S. S. Mahapatra ◽  
S. Shekhar ◽  
B. K. Thakur ◽  
H. Priyadarshi
Keyword(s):  
Methanol Oxidation ◽  
Electrocatalytic Activity ◽  
Electrochemical Impedance ◽  
Synergistic Effects ◽  
Catalytic Performance ◽  
Charge Transfer Resistance ◽  
Pani Film ◽  
Composite Electrodes ◽  
Transfer Resistance ◽  
Onset Potential

Electropolymerization of aniline at the graphite electrodes was achieved by potentiodynamic method. Electrodeposition of Pd (C-PANI-Pd) and Ni (C-PANI-Ni) and codeposition of Pd-Ni (C-PANI-Pd-Ni) microparticles into the polyaniline (PANI) film coated graphite (C-PANI) were carried out under galvanostatic control. The morphology and composition of the composite electrodes were obtained using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX) techniques. The electrochemical behavior and electrocatalytic activity of the electrode were characterized using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometric (CA) methods in acidic medium. The C-PANI-Pd-Ni electrode showed an improved catalytic performance towards methanol oxidation in terms of lower onset potential, higher anodic oxidation current, greater stability, lower activation energy, and lower charge transfer resistance. The enhanced electrocatalytic activity might be due to the greater permeability of C-PANI films for methanol molecules, better dispersion of Pd-Ni microparticles into the polymer matrixes, and the synergistic effects between the dispersed metal particles and their matrixes.

Preparation and electrochemical characterization of PANI/MnCo2O4 nanocomposite as supercapacitor electrode material

2018 ◽  
Vol 96 (5) ◽  
pp. 477-483 ◽  
Author(s):  
Saeid Panahi ◽  
Moosa Es’haghi
Keyword(s):  
Specific Capacitance ◽  
Surface Characterization ◽  
Electrochemical Impedance ◽  
Rate Capability ◽  
Cycling Performance ◽  
Charge Transfer Resistance ◽  
X Ray Diffraction ◽  
Supercapacitor Electrode ◽  
Transfer Resistance

In this work, PANI/MnCo2O4 nanocomposite was prepared via in-situ chemical polymerization method. Materials synthesized were characterized by FTIR spectroscopy, X-ray diffraction, and scanning electron spectroscopy. In addition, surface characterization of samples such as specific surface area, pore volume, and pore size distribution was studied. Supercapacitor capability of materials was investigated in 1 mol L–1 Na2SO4 solution using cyclic voltammetry in different potential scan rates and electrochemical impedance spectroscopy (EIS). The specific capacitance of materials was calculated, and it was observed that the specific capacitance of PANI/MnCo2O4 nanocomposite was 185 F g−1, much larger than PANI. Moreover, the prepared nanocomposite exhibited better rate capability in scan rate of 100 mV s−1 with respect to PANI. The EIS experiments revealed that the nanocomposite has lower charge transfer resistance compared with pure PANI. Subsequently, it was shown that the nanocomposite cycling performance was superior to the PANI cycling performance.

scholarly journals Electrochemical Characterization of a New Biodegradable FeMnSi Alloy Coated with Hydroxyapatite-Zirconia by PLD Technique

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Nicanor Cimpoeşu ◽  
Lucia Carmen Trincă ◽  
Georgiana Dascălu ◽  
Sergiu Stanciu ◽  
Silviu Octavian Gurlui ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Electrochemical Behavior ◽  
Electrochemical Impedance ◽  
Corrosion Current ◽  
Charge Transfer Resistance ◽  
Transfer Resistance ◽  
Zero Current ◽  
Capacitive Effect ◽  
Current Potential

Biodegradable alloys are very attractive biomaterials. Electrochemical impedance spectroscopy (EIS) and linear potentiodynamic polarization (LPP) techniques were used for the study of the electrochemical behavior of uncoated FeMnSi and coated FeMnSi with hydroxyapatite + zirconia (HA-ZrO2) through pulsed laser deposition (PLD) technique. Experiments were carried out using Hank’s balanced salt solution (HBSS). It has been shown that in HBSS the impedance for uncoated FeMnSi was mainly characterized by one capacitive effect, which related to the alloy charge transfer control. The charge transfer resistance increases for HA-ZrO2-coated FeMnSi alloy. The equivalent circuits simulating the electrochemical behavior of both uncoated and HA-ZrO2-coated FeMnSi alloys in HBSS were proposed. From LPP the corrosion resistance was evaluated by means of the zero current potential (ZCP) and corrosion current density (jcorr). The surface morphology of both uncoated and HA-coated FeMnSi alloys in HBSS obtained after LPP was studied using scanning electron microscopy (SEM).

Effect of Morphology of Conducting Polymer on DNA Sensing

2011 ◽  
Vol 700 ◽  
pp. 211-214
Author(s):  
Bhuvaneswari Kannan ◽  
David E. Williams ◽  
Jadranka Travas-Sejdic
Keyword(s):  
Electron Transfer ◽  
Electrode Surface ◽  
Electrochemical Impedance ◽  
Charge Transfer Resistance ◽  
Electron Charge ◽  
Dna Sensors ◽  
Transfer Resistance ◽  
Electron Charge Transfer ◽  
Kinetics Of ◽  
Biosensor Applications

Electrochemical DNA sensors can be constructed by understanding basic interfacial electron transfer between solid surface-electrolyte-DNA interfaces. The kinetics of this heterogeneous process can be significantly affected by the microstructure and roughness of the electrode surface. By understanding this concept, in this paper; we compared the performance of micro electrodes containing poly(Py-co-PAA) with macro electrode containing same copolymer, showing that micro electrodes are more sensitive than the macro electrodes for biosensor applications. Sensors based on the copolymer electropolymerised on both micro and macro electrodes were evaluated across a range of oligonucleotide concentrations. The interfacial electron charge transfer resistance between the solution and electrode surface was studied using electrochemical impedance spectroscopy (EIS).

Effects of Different Carbon Nanotube Supported Catalysts on Methanol and Ethanol Electro-Oxidation

2009 ◽  
Vol 1213 ◽  
Author(s):  
Raghavendar Reddy Sanganna Gari ◽  
Zhou Li ◽  
Lifeng Dong
Keyword(s):  
Carbon Nanotubes ◽  
Current Density ◽  
Electrochemical Impedance ◽  
Charge Transfer Resistance ◽  
Forward Peak ◽  
Peak Current Density ◽  
Transfer Resistance ◽  
Peak Current ◽  
Ru Nanoparticles ◽  
Walled Carbon Nanotubes

AbstractIn this work, Pt and Pt-Ru nanoparticles were synthesized on both single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs). Effects of different nanotube supports on electrocatalytic activity of Pt and Pt-Ru nanoparticles for methanol and ethanol oxidations were investigated using cyclic voltammetry and electrochemical impedance spectroscopy. In comparison to MWCNTs, SWCNT supported Pt and Pt-Ru catalysts demonstrate better electrocatalytic activities in terms of forward peak current density, the ratio of forward peak current density to reverse peak current density, and charge transfer resistance. This study indicates that SWCNTs can serve as effective catalyst supports for both direct methanol and ethanol fuel cells.

Improvement of Ti/RuO2–IrO2 Anode Lifetime and Electrocatalytical Properties by Using an Eco-Friendly Thermal Decomposition Method Using Polyvinyl Alcohol as Solvent

2019 ◽  
Author(s):  
Charlys Bezerra ◽  
Géssica Santos ◽  
Marilia Pupo ◽  
Maria Gomes ◽  
Ronaldo Silva ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Polyvinyl Alcohol ◽  
High Efficiency ◽  
Electrochemical Impedance ◽  
Pechini Method ◽  
Low Cost ◽  
Charge Transfer Resistance ◽  
Transfer Resistance ◽  
Calcination Temperatures ◽  
Service Lifetime

<p>Electrochemical oxidation processes are promising solutions for wastewater treatment due to their high efficiency, easy control and versatility. Mixed metal oxides (MMO) anodes are particularly attractive due to their low cost and specific catalytic properties. Here, we propose an innovative thermal decomposition methodology using <a>polyvinyl alcohol (PVA)</a> as a solvent to prepare Ti/RuO<sub>2</sub>–IrO<sub>2</sub> anodes. Comparative anodes were prepared by conventional method employing a polymeric precursor solvent (Pechini method). The calcination temperatures studied were 300, 400 and 500 °C. The physical characterisation of all materials was performed by X-ray diffraction and scanning electron microscopy coupled with energy dispersive spectroscopy, while electrochemical characterisation was done by cyclic voltammetry, accelerated service lifetime and electrochemical impedance spectroscopy. Both RuO<sub>2</sub> and IrO<sub>2</sub> have rutile-type structures for all anodes. Rougher and more compact surfaces are formed for the anodes prepared using PVA. Amongst temperatures studied, 300 °C using PVA as solvent is the most suitable one to produce anodes with expressive increase in voltammetric charge (250%) and accelerated service lifetime (4.3 times longer) besides reducing charge-transfer resistance (8 times lower). Moreover, the electrocatalytic activity of the anodes synthesised with PVA toward the Reactive Blue 21 dye removal in chloride medium (100 % in 30 min) is higher than that prepared by Pechini method (60 min). Additionally, the removal total organic carbon point out improved mineralisation potential of PVA anodes. Finally, this study reports a novel methodology using PVA as solvent to synthesise Ti/RuO<sub>2</sub>–IrO<sub>2</sub> anodes with improved properties that can be further extended to synthesise other MMO compositions.</p>

scholarly journals Electrochemical Immunosensor for the Quantification of S100B at Clinically Relevant Levels Using a Cysteamine Modified Surface

Sensors ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 1929
Author(s):  
Alexander Rodríguez ◽  
Francisco Burgos-Flórez ◽  
José D. Posada ◽  
Eliana Cervera ◽  
Valtencir Zucolotto ◽  
...  
Keyword(s):  
Frequency Analysis ◽  
Surface Characterization ◽  
Electrochemical Impedance ◽  
Limit Of Detection ◽  
Neuronal Damage ◽  
Charge Transfer Resistance ◽  
Single Frequency ◽  
Response Analysis ◽  
Transfer Resistance ◽  
Therapeutic Decisions

Neuronal damage secondary to traumatic brain injury (TBI) is a rapidly evolving condition, which requires therapeutic decisions based on the timely identification of clinical deterioration. Changes in S100B biomarker levels are associated with TBI severity and patient outcome. The S100B quantification is often difficult since standard immunoassays are time-consuming, costly, and require extensive expertise. A zero-length cross-linking approach on a cysteamine self-assembled monolayer (SAM) was performed to immobilize anti-S100B monoclonal antibodies onto both planar (AuEs) and interdigitated (AuIDEs) gold electrodes via carbonyl-bond. Surface characterization was performed by atomic force microscopy (AFM) and specular-reflectance FTIR for each functionalization step. Biosensor response was studied using the change in charge-transfer resistance (Rct) from electrochemical impedance spectroscopy (EIS) in potassium ferrocyanide, with [S100B] ranging 10–1000 pg/mL. A single-frequency analysis for capacitances was also performed in AuIDEs. Full factorial designs were applied to assess biosensor sensitivity, specificity, and limit-of-detection (LOD). Higher Rct values were found with increased S100B concentration in both platforms. LODs were 18 pg/mL(AuES) and 6 pg/mL(AuIDEs). AuIDEs provide a simpler manufacturing protocol, with reduced fabrication time and possibly costs, simpler electrochemical response analysis, and could be used for single-frequency analysis for monitoring capacitance changes related to S100B levels.

scholarly journals Influence of HAP on the Morpho-Structural Properties and Corrosion Resistance of ZrO2-Based Composites for Biomedical Applications

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 202
Author(s):  
Réka Barabás ◽  
Carmen Ioana Fort ◽  
Graziella Liana Turdean ◽  
Liliana Bizo
Keyword(s):  
Electrochemical Impedance ◽  
Artificial Saliva ◽  
Synergetic Effect ◽  
Composite Layer ◽  
Charge Transfer Resistance ◽  
Processing Route ◽  
Dental Alloys ◽  
Metallic Electrode ◽  
Transfer Resistance ◽  
X Ray

In the present work, ZrO2-based composites were prepared by adding different amounts of antibacterial magnesium oxide and bioactive and biocompatible hydroxyapatite (HAP) to the inert zirconia. The composites were synthesized by the conventional ceramic processing route and morpho-structurally analyzed by X-ray powder diffraction (XRPD) and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS). Two metallic dental alloys (i.e., Ni–Cr and Co–Cr) coated with a chitosan (Chit) membrane containing the prepared composites were exposed to aerated artificial saliva solutions of different pHs (i.e., 4.3, 5, 6) and the corrosion resistances were investigated by electrochemical impedance spectroscopy technique. The obtained results using the two investigated metallic dental alloys shown quasi-similar anticorrosive properties, having quasi-similar charge transfer resistance, when coated with different ZrO2-based composites. This behavior could be explained by the synergetic effect between the diffusion process through the Chit-composite layer and the roughness of the metallic electrode surface.

scholarly journals Corrosion behaviors of 316 stainless steel and Inconel 625 alloy in chloride molten salts for solar energy storage

2020 ◽  
Vol 39 (1) ◽  
pp. 340-350
Author(s):  
Mingjing Wang ◽  
Song Zeng ◽  
Huihui Zhang ◽  
Ming Zhu ◽  
Chengxin Lei ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Molten Salt ◽  
Electrochemical Impedance ◽  
Charge Transfer Resistance ◽  
Inconel 625 ◽  
Transfer Resistance ◽  
316 Stainless Steel ◽  
Corrosion Rates ◽  
Inconel 625 Alloy ◽  
Corrosion Behaviors

AbstractCorrosion behaviors of 316 stainless steel (316 ss) and Inconel 625 alloy in molten NaCl–KCl–ZnCl2 at 700°C and 900°C were investigated by immersion tests and electrochemical methods, including potentiodynamic polarization and electrochemical impedance spectroscopy. X-ray diffraction and scanning electron microscopy/energy dispersive spectroscopy were used to analyze the phases and microstructures of the corrosion products. Inconel 625 alloy and 316 ss exhibited high corrosion rates in molten chlorides, and the corrosion rates of these two alloys accelerated when the temperature increased from 700°C to 900°C. The results of the electrochemical tests showed that both alloys exhibited active corrosion in chloride molten salt, and the current density of 316 ss in chloride molten salt at 700°C was 2.756 mA/cm−2, which is about three times the value for Inconel 625 alloy; and the values of the charge transfer resistance (Rt) for Inconel 625 were larger than those for 316 ss. The corrosion of these two alloys is owing to the preferred oxidation of Cr in chloride molten salt, and the corrosion layer was mainly ZnCr2O4 which was loose and porous and showed poor adherence to metal.

Sign in / Sign up

Export Citation Format

Share Document