Generation of a Highly Efficient Electrode for Ethanol Oxidation by Simply Electrodepositing Palladium on the Oxygen Plasma-Treated Carbon Fiber Paper

In this study, a highly efficient carbon-supported Pd catalyst for the direct ethanol fuel cell was developed by electrodepositing nanostructured Pd on oxygen plasma-treated carbon fiber paper (Pd/pCFP). The oxygen plasma treatment has been shown to effectively remove the surface organic contaminants and add oxygen species onto the CFP to facilitate the deposition of nano-structured Pd on the surface of carbon fibers. Under the optimized and controllable electrodeposition method, nanostructured Pd of ~10 nm can be easily and evenly deposited onto the CFP. The prepared Pd/pCFP electrode exhibited an extraordinarily high electrocatalytic activity towards ethanol oxidation, with a current density of 222.8 mA mg−1 Pd. Interestingly, the electrode also exhibited a high tolerance to poisoning species and long-term stability, with a high ratio of the forward anodic peak current density to the backward anodic peak current density. These results suggest that the Pd/pCFP catalyst may be a promising anodic material for the development of highly efficient direct alcohol fuel cells.

Fabrication of an Extremely Cheap Poly(3,4-ethylenedioxythiophene) Modified Pencil Lead Electrode for Effective Hydroquinone Sensing

Hydroquinone (HQ) is one of the major deleterious metabolites of benzene in the human body, which has been implicated to cause various human diseases. In order to fabricate a feasible sensor for the accurate detection of HQ, we attempted to electrochemically modify a piece of common 2B pencil lead (PL) with the conductive poly(3,4-ethylenedioxythiophene) or PEDOT film to construct a PEDOT/PL electrode. We then examined the performance of PEDOT/PL in the detection of hydroquinone with different voltammetry methods. Our results have demonstrated that PEDOT film was able to dramatically enhance the electrochemical response of pencil lead electrode to hydroquinone and exhibited a good linear correlation between anodic peak current and the concentration of hydroquinone by either cyclic voltammetry or linear sweep voltammetry. The influences of PEDOT film thickness, sample pH, voltammetry scan rate, and possible chemical interferences on the measurement of hydroquinone have been discussed. The PEDOT film was further characterized by SEM with EDS and FTIR spectrum, as well as for stability with multiple measurements. Our results have demonstrated that the PEDOT modified PL electrode could be an attractive option to easily fabricate an economical sensor and provide an accurate and stable approach to monitoring various chemicals and biomolecules.

Novel Electrochemical Sensor for Rifampicin based on Ionic Liquid Functionalised TiO2 Nanoparticles

Aim: The main strategy of this study is to develop a novel ionic liquid functionalised metal nanocomposite based electrochemical sensor with potential applications for the sensitive electrochemical detection of rifampicin. Background: Tuberculosis (TB) is a widespread disease that is caused by the gram-positive Mycobacterium tuberculosis (MTB). In addition, for several decades TB has become a constant threat to human health, however due to the accessibility of broad-spectrum antibiotics (rifampicin, pyrazinamide, isoniazid, and ethambutol), which are active against the bacterium, the social and economic burden for sufferers from the illness remains to be huge. Specially, in countries, like India and sub Saharan Africa, it is one of the common diseases affecting members from all age groups. So, this work is aimed at developing a novel electrochemical sensor for the determination of rifampicin (RIF) in pharmaceutical samples. Objective: To synthesis and characterization of the novel liquid functionalised metal nanocomposite. Fabrication of glassy carbon electrode with potent electrode modifiers whose applicability as electro catalysis agents towards rifampicin is investigated. Method: In this work, a nanocomposite based on trihexyltetradecylphosphonium-bis-(2,4,4-trimethylpentyl)-phosphinate ([P14, 6, 6, 6] [(C8H17)2 PO2)]) ionic liquid functionalised titanium oxide nanoparticles (TiO2NPs) and multiwalled carbon nanotubes (MWCNTs) were used in the modification of a highly sensitive electrochemical sensor for quantification of rifampicin in pharmaceutical formulations. The modified glassy carbon electrode (GCE) were characterised by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). Results: The electrochemical behaviour of RIF was studied on the modified electrode by the cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. At pH 6.0 in phosphate buffer solution (PBS), the anodic peak current value of RIF obtained with the fabricated electrode is 7 times greater than with the bare GCE electrode. The anodic peak current value and concentration of RIF showed a good linear relationship in the range of 0.015–2.8 μM, with the limit of detection (LOD) of 0.0218 μM and limit of quantification (LOQ) 0.3120 μM respectively. Conclusion: Under the optimal conditions, the IL-f-TiO2NPs-MWCNTs-GCE provided a relatively lower detection limit and wider linear range compared to other previous procedures. The proposed electrochemical sensor had potent catalytic activity for RIF oxidation and provided important quantitatively reproducible analytical performance. Finally, this modified electrode was successfully applied to the determination of RIF in real pharmaceutical samples.

Synthesis, Antioxidant Activity, and Determination of Binding Parameters of Meso-Tetra-4-Actophenyl-Porphyrin and its Palladium (II) Complex with Superoxide Anion Radicals

Background: Meso-tetra-4-actophenyl-porphyrin (TAcPPH2) was synthesized by reacting 4- acetyl-benzaldehyde with pyrrole in propionic acid, and used as a ligand for the synthesis of palladium (II) complex (PdTAcPP). The structure of the ligand and the complex were characterized by NMR and electronic spectroscopy. Methods: he antioxidant activity and the binding parameters of both the ligand and its complex with superoxide anion radical . (O2 -) were measured using cyclic voltammetry based assay. The assays were based on the measurement of the anodic peak current density of . O2− electrochemically generated by reduction of molecular oxygen in DMF. Results: The complex PdTAcPP showed the highest antioxidant activity (0.73 ± 0.01 mg/mL) which is four times higher than that of the standard antioxidant α-tocopherol (3.04 ± 0.03 mg/mL). Discussion: Binding parameters like binding constants, the ratio of binding constants and binding free energies were also measured. Conclusion: The value of the binding free energy ranging from -7.89 kJmol-1 for TAcPPH2 to -17.59 kJ.mol-1for PdTAcPP suggests an electrostatic interaction of . O2− with TAcPPH2 and PdTAcPP which has been found to be the dominant interaction mode. The kinetics of the interaction reaction of the ligand and complex was quantified having second-order rate constant values equal to 0.2 and 1.3 M-1 s-1, respectively.

“Painted” CNT@Au Nanoparticles: A Nanohybrid Electrocatalyst of Direct Methanol Oxidation

<p>In a world of constant rush towards novel energy sources, hybrid nanomaterials have raised huge interest as their components can synergistically improve the expected performances in terms of power. In this regard, direct methanol oxidation (DMO) is among the most investigated reactions for implementation in portable and other devices. Herein, we report the design of gold-decorated CNT-aryl nanohybrids as electrocatalyst of DMO. In a first step, Azure A (AA), Neutral Red (NR) and Congo Red (CR) dye diazonium salts were reacted with CNTs to provide CNT-Dye nanoscale platforms for the immobilization of gold NPs. This step was conducted with CNT-Dye platforms evenly spread over glassy carbon (GC) electrodes. The CNT-Dye@Au nanohybrid electrode materials served for DMO electrocatalysis. Cyclic voltammograms show that bare CNT-Dye nanohybrids exhibit high electrocatalytic activity, particularly for the CNT-CR nanohybrid which returned a 3-fold improvement. With anchored Au NPs, a further 4 time remarkable increase in the oxidation peak intensity was achieved (<i>i.e.</i> about 12-fold the peak intensity recorded in the absence of any nanocatalyst). The forward to the backward anodic peak current density ratio J_f/J_b was found to be as high as is 1.68. </p><p> This work provides a simple, elegant and efficient approach for designing robust, nanohybrid electrocatalyst for DMO, based on the smart combination of CNTs, diazotized dyes and gold NPs.<br></p>

“Painted” CNT@Au Nanoparticles: A Nanohybrid Electrocatalyst of Direct Methanol Oxidation

<p>In a world of constant rush towards novel energy sources, hybrid nanomaterials have raised huge interest as their components can synergistically improve the expected performances in terms of power. In this regard, direct methanol oxidation (DMO) is among the most investigated reactions for implementation in portable and other devices. Herein, we report the design of gold-decorated CNT-aryl nanohybrids as electrocatalyst of DMO. In a first step, Azure A (AA), Neutral Red (NR) and Congo Red (CR) dye diazonium salts were reacted with CNTs to provide CNT-Dye nanoscale platforms for the immobilization of gold NPs. This step was conducted with CNT-Dye platforms evenly spread over glassy carbon (GC) electrodes. The CNT-Dye@Au nanohybrid electrode materials served for DMO electrocatalysis. Cyclic voltammograms show that bare CNT-Dye nanohybrids exhibit high electrocatalytic activity, particularly for the CNT-CR nanohybrid which returned a 3-fold improvement. With anchored Au NPs, a further 4 time remarkable increase in the oxidation peak intensity was achieved (<i>i.e.</i> about 12-fold the peak intensity recorded in the absence of any nanocatalyst). The forward to the backward anodic peak current density ratio J_f/J_b was found to be as high as is 1.68. </p><p> This work provides a simple, elegant and efficient approach for designing robust, nanohybrid electrocatalyst for DMO, based on the smart combination of CNTs, diazotized dyes and gold NPs.<br></p>

Dye-grafted CNTs@Au nanoparticles: a nanohybrid electrocatalyst of direct methanol oxidation

<p>In a world of constant rush towards novel energy sources, hybrid nanomaterials have raised huge interest as their components can synergistically improve the expected performances in terms of power. In this regard, direct methanol oxidation (DMO) is among the most investigated reactions for implementation in portable and other devices. Herein, we report the design of gold-decorated CNT-aryl nanohybrids as electrocatalyst of DMO. In a first step, Azure A (AA), Neutral Red (NR) and Congo Red (CR) dye diazonium salts were reacted with CNTs to provide CNT-Dye nanoscale platforms for the immobilization of gold NPs. This step was conducted with CNT-Dye platforms evenly spread over glassy carbon (GC) electrodes. The CNT-Dye@Au nanohybrid electrode materials served for DMO electrocatalysis. Cyclic voltammograms show that bare CNT-Dye nanohybrids exhibit high electrocatalytic activity, particularly for the CNT-CR nanohybrid which returned a 3-fold improvement. With anchored Au NPs, a further 4 time remarkable increase in the oxidation peak intensity was achieved (<i>i.e.</i> about 12-fold the peak intensity recorded in the absence of any nanocatalyst). The forward to the backward anodic peak current density ratio J_f/J_b was found to be as high as is 1.68. </p> <p>This work provides a simple, elegant and efficient approach for designing robust, nanohybrid electrocatalyst for DMO, based on the smart combination of CNTs, diazotized dyes and gold NPs.</p><br>

Evaluation of Stainless Steel as an Electrocatalyst for Electrooxidation of Urea - Rich Wastewater

In this study, commercially available bare stainless steel 304 was investigated as a working electrode in urea electrooxidation in alkaline solution using different electrochemical techniques like cyclic voltammetry (CV) and linear sweep voltammetry (LSV). The electrode stability was also investigated by the constant potential electrolysis test. Different concentrations of KOH (0.5-4 M) were employed to study the electrooxidation of urea solution with concentration of 0.33 M. An anodic peak current density of 34.82mA/cm2 was obtained at 473 mV versus Ag/AgCl reference electrode in urea solution at KOH concentration of 4 M. Stainless steel properties such as corrosion resistance, low cost in addition to its catalytic activity make it an ideal anodic electrocatalyst for electrooxidation of urea-rich wastewater.

Voltammetric Method Development for Itopride Assay in a Pharmaceutical Formulation

Background: Itopride used for the gastrointestinal symptoms caused by reduced gastrointestinal mobility. For the first time rapid, low cost and green voltammetric method has been applied to analyze itopride in pharmaceutical formulation. Method: Cyclic Voltammetry (CV), Linear Sweep Voltammetry (LSV), Square Wave Voltammetry (SWV) and Differential Pulse Voltammetry (DPV) methods have been applied in this study. Results: Na2SO4 (1M) supporting electrolyte exhibited sharper anodic peak current than other used supporting electrolytes; glassy carbon electrode (GC) working electrode shows better results than platinum electrode (Pt). SWV results show the lowest limit of detection and quantitation values of 2.3 and 18.1 μg.mL-1, respectively. SWV recovery is 100.56% and 100.46% for 50 μg.mL-1 and 100 μg.mL-1 of commercially available itopride tablets, respectively. Furthermore, SWV inter and intraday results precessions are better than other used methods with 0.96 and 0.56% RSD, respectively. Conclusion: The optimum method of applied methods in this study is SWV method. Voltammetry showed low LOD and LOQ values with high accuracy and precession in addition to comparable repeatability and reproducibility values.

La2O3/Co3O4 nanocomposite modified screen printed electrode for voltammetric determination of sertraline

La2O3/Co3O4 nanocomposite was synthesized and then used for the modification of screen-printed electrode (SPE) prior to the electrochemical determination of sertraline. A significant increment in peak current response was observed and peak potential also shifted towards less positive potentials showing the facilitated oxidation procedure at surface of modified SPE (La2O3/ /Co3O4/SPE). The quantitative determination of sertraline was carried out by using different pulse voltammetry and the anodic peak current was found to increase with increasing sertraline concentration in the linear range of 5.0400.0 ?M with limit of detection as 1.0 ?M. The prepared La2O3/Co3O4/SPE has been successfully used for detecting sertraline in sertraline tablet and urine samples with excellent recoveries.