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.

scholarly journals New Generation of Electrochemical Sensors Based on Multi-Walled Carbon Nanotubes

2018 ◽  
Vol 8 (10) ◽  
pp. 1925 ◽  
Author(s):  
Thiago Oliveira ◽  
Simone Morais
Keyword(s):  
Carbon Nanotubes ◽  
Electrochemical Sensors ◽  
Industrial Applications ◽  
Charge Transfer Resistance ◽  
Active Surface Area ◽  
Synthesis Methods ◽  
Transfer Resistance ◽  
Multi Walled Carbon Nanotubes ◽  
New Generation ◽  
Walled Carbon Nanotubes

Multi-walled carbon nanotubes (MWCNT) have provided unprecedented advances in the design of electrochemical sensors. They are composed by sp2 carbon units oriented as multiple concentric tubes of rolled-up graphene, and present remarkable active surface area, chemical inertness, high strength, and low charge-transfer resistance in both aqueous and non-aqueous solutions. MWCNT are very versatile and have been boosting the development of a new generation of electrochemical sensors with application in medicine, pharmacology, food industry, forensic chemistry, and environmental fields. This work highlights the most important synthesis methods and relevant electrochemical properties of MWCNT for the construction of electrochemical sensors, and the numerous configurations and successful applications of these devices. Thousands of studies have been attesting to the exceptional electroanalytical performance of these devices, but there are still questions in MWCNT electrochemistry that deserve more investigation, aiming to provide new outlooks and advances in this field. Additionally, MWCNT-based sensors should be further explored for real industrial applications including for on-line quality control.

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.

PREPARATION AND CHARACTERIZATION OF A POLY(PYRROLYL METHANE)/MULTIWALLED CARBON NANOTUBES COMPOSITES

NANO ◽  
2013 ◽  
Vol 08 (06) ◽  
pp. 1350063
Author(s):  
JINXIAN LIN ◽  
PAN WANG ◽  
YUYING ZHENG
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Multiwalled Carbon Nanotubes ◽  
Electrochemical Impedance ◽  
Charge Transfer Resistance ◽  
Electrode System ◽  
X Ray Diffraction ◽  
Multiwalled Carbon ◽  
Transfer Resistance ◽  
Transmission Electron

A poly(pyrrolyl methane) (Poly[pyrrole-2, 5-diyl(4-methoxybenzylidane)], PPDMOBA)/multiwalled carbon nanotubes (MWNTs) composites are fabricated by in situ chemical polycondensation of pyrrole and 4-methoxybenzaldehyde on MWNTs. The structure, morphology, thermal stability and electrical property of the resulting composites are investigated via fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and a four-probe method. The electrochemical performance of the composites is determined in a three-electrode system using cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) and electrochemical impedance spectroscopy (EIS) techniques. FTIR, FESEM and TEM confirm that the composites have been successfully prepared, and PPDMOBA is uniformly dispersed in MWNTs. Electrical conductivity of PPDMOBA/MWNTs composites is 1.39 S cm-1, which is significantly larger than that of pristine PPDMOBA. The specific capacitance and charge transfer resistance of the composites is 56 F g-1 (1 mA cm-2) and 0.3Ω, respectively.

scholarly journals MORPHOLOGICAL, STRUCTURAL, MICROHARDNESS AND ELECTROCHEMICAL CHARACTERIZATIONS OF ELECTRODEPOSITED Cr AND Ni–W COATINGS

2018 ◽  
Vol 24 (3) ◽  
pp. 234 ◽  
Author(s):  
Elkhanssa Aidaoui ◽  
Hachemi Ben Temam ◽  
Okba Belahssen ◽  
El Hachmi Guettaf Temam
Keyword(s):  
Current Density ◽  
Electrochemical Impedance ◽  
Electrochemical Characterizations ◽  
Copper Substrate ◽  
Charge Transfer Resistance ◽  
Applied Current ◽  
Transfer Resistance ◽  
Electrochemical Tests ◽  
Cu Substrates ◽  
Xrd Patterns

<p class="AMSmaintext">Currently, Ni-Cr coatings are widely used in a number of important applications due to their excellent properties. In this study, Ni-Cr alloys were electrodeposited from citrate bath onto Cu substrates by using different values of applied current densities. The effects of plating deposition current density on morphological and structural characterization of Ni-Cr electrodeposited coatings were investigated by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD). Microhardness of the coatings is also evaluated using Vickers’s microhardness. Potentio-dynamic polarization and electrochemical impedance spectroscopy (EIS) tests in 3.5wt % NaCl solution were used to evaluate corrosion résistance of Ni-Cr coatings. The results showed that the surface morphology of the all coatings contained micro cracks and pores. XRD patterns indicate the formation of Ni-Cr and Cr<sub>3</sub>Ni<sub>2</sub> phases. Microhardness measurements show that all Ni-Cr samples are hardener than copper substrate. Electrochemical tests show that 3 A/dm² is an optimal value of applied current density in the sense of the least value of E<sub>corr</sub> and the best charge transfer resistance R<sub>p</sub>.</p>

scholarly journals Controlled Layer-By-Layer Deposition of Carbon Nanotubes on Electrodes for Microbial Fuel Cells

Energies ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 363 ◽  
Author(s):  
Wenguo Wu ◽  
Hao Niu ◽  
Dayun Yang ◽  
Shi-Bin Wang ◽  
Jiefu Wang ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Fuel Cells ◽  
Modified Electrode ◽  
Current Density ◽  
Indium Tin Oxide ◽  
Microbial Fuel Cells ◽  
Electrochemical Impedance ◽  
Layer By Layer ◽  
Peak Current ◽  
Ito Electrode

Carbon nanotubes (CNTs) and polyelectrolyte poly(allylamine hydrochloride) (PAH) composite modified indium tin oxide (ITO) electrodes, by a layer-by-layer (LBL) self-assembly technique, was evaluated as an anode for microbial fuel cells (MFCs). The bioelectrochemistry of Shewanella loihica PV-4 in an electrochemical cell and the electricity generation performance of MFCs with multilayer (CNTs/PAH)n-deposited ITO electrodes as an anode were investigated. Experimental results showed that the current density generated on the multilayer modified electrode increased initially and then decreased as the deposition of the number of layers (n = 12) increased. Chronoamperometric results showed that the highest peak current density of 34.85 ± 2.80 mA/m2 was generated on the multilayer (CNTs/PAH)9-deposited ITO electrode, of which the redox peak current of cyclic voltammetry was also significantly enhanced. Electrochemical impedance spectroscopy analyses showed a well-formed nanostructure porous film on the surface of the multilayer modified electrode. Compared with the plain ITO electrode, the multilayered (CNTs/PAH)9 anodic modification improved the power density of the dual-compartment MFC by 29%, due to the appropriate proportion of CNTs and PAH, as well as the porous nanostructure on the electrodes.

Cyclic Voltammetric Studies on Selected Tin-Silver Binary Alloys in Sodium Hydroxide Solution

CORROSION ◽  
2010 ◽  
Vol 66 (11) ◽  
pp. 115001-115001-12 ◽  
Author(s):  
A. A. Ghoneim ◽  
M. A. Ameer ◽  
A. M. Fekry ◽  
F. El-Taib Heakal
Keyword(s):  
Sodium Hydroxide ◽  
Current Density ◽  
Electrochemical Impedance ◽  
Sodium Hydroxide Solution ◽  
Cyclic Voltammograms ◽  
Reduction Peak ◽  
Peak Potential ◽  
Relative Thickness ◽  
Peak Current Density ◽  
Peak Current

Abstract The electrochemical corrosion and passivation behavior of four selected tin-silver alloys, xSn-Ag (x = 26, 50, 70, and 96.5 wt%) (II through V), in addition to their pure metallic components, Ag(I) and Sn(VI), were investigated in aqueous sodium hydroxide (NaOH) solution. The techniques used are linear sweep cyclic voltammetry and electrochemical impedance spectroscopy (EIS). In general, for all studied samples, the cyclic voltammograms show that increasing the scan rate shifts the passivation peak potential (Ep,a) positively and the reduction peak potential (Ep,c) negatively with a concomitant increase in both the passivation peak current density (ip,a) and the reduction peak current density (ip,c). EIS results investigate that the total resistance (RT) and the relative thickness (1/C) of the passive layers on the six tested electrodes are both found to increase with time of immersion, being more pronounced for sample II. Although this silver-rich alloy (74 wt%) has the most protectiveness among the tested specimens, the relative thickness of its passive film is much lower than that for the pure silver. After any immersion period the passivation sequence of the six samples can be arranged in the following order:II ≫ I &gt; IV &gt; III &gt; V &gt; VI.

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.

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