جستجوی مقالات مرتبط با کلیدواژه « Graphite electrode » در نشریات گروه « شیمی »

Graphene oxide nanosheets (GONs) are ideally suited for implementation in electrochemical applications due to their large electrical conductivity, large surface area and low production costs. In this research, electrochemical exfoliated graphene oxide-modified graphite electrode was developed for voltammetric determination of clozapine (CLZ). The dependence of oxidation peak current on the pH of the solution, scan rate and concentration of analyte were studied to optimize the experimental conditions for electrochemical determination of CLZ. The experimental results suggested that the modified electrode promoted electron transfer reaction for the oxidation of CLZ. The modified electrode exhibited high effective surface area, more reactive sites and excellent electrocatalytic activity toward the oxidation of CLZ. In the concentration range of 0.75–100 µM of CLZ in citrate buffer solution (CBS, pH 6), the anodic peak currents, measured via differential pulse voltammetry (DPV), presented good linear relationship with limit of detection (LOD) of 2.15 nM and good sensitivity of 0.0477 µA µM−1. The proposed method was successfully applied to quantify the amount of CLZ in the blood serum and plasma of schizophrenia patient.

Aminoguanidine (AG), as a group of nucleophilic hydrazine compounds, has different pharmacological activities, like reducing the pathological consequence of diabetes. Here, the electrochemical oxidation behavior of aminoguanidine was examined, directly at bare graphite electrode and indirectly, with theophylline hybrid polymer and copper oxide nanoparticles, using cyclic voltammetry (CV) and square wave voltammetry (SWV). The impact of pH, buffer type, time, and concentration were studied in the two methods. Two oxidation peaks were found at (0.773 V , 1.15 V) vs. Ag/AgCl in acetate buffer (0.1 M, pH 4.5) and (0.8 V , 1.1 V) vs. Ag/AgCl in phosphate buffer (0.1 M, pH 7.0). At graphite bare electrode (GCE), the optimal result was achieved when the phosphate buffer was used, changing the linear range for the detection of aminoguanidine at bare electrode from 299.1 to 990 µM with R2 of 0.992 and standard deviation of 33.5 µM. At modified graphite electrode with theophylline hybrid polymer and copper oxide nanoparticles (GCE-poly TP/CuO-NPs), a much wider range was obtained for AG, at 9.9 to 610.316 µM with R2 =0.990 the limit of detection of 6.34 µM, and SD of 0.089 µM. Finally, the preparation of modified graphite electrode with nanoparticles (GCE-poly TP/CuO NPs) showed good stability, persisting for more than 2 weeks, and showing a potential to be used as a drug sensor.

In this study, a simple and efficient approach is reported to product graphene using electrochemical exfoliation of graphite electrodes, in acidic solutions. The electrolyte concentration, applied voltages, electrodes distance and preparation time were taken as control parameters to optimize the produced graphene structures. The optimized graphene sample was prepared in a H2SO4 (0.5 M) at a bias of +10 V. The interlayer spaces, crystallite size and the average number of layers were determined by XRD. Surface morphology, layer thickness and characteristics of obtained samples were investigated by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), and FTIR. The obtained results confirmed the graphene structures.

In this article, the effect of the electrode surface morphology is investigated in the methanol electrooxidation process. For this purpose, a Ni-P layer of fine structure and two different Ni-B coatings having granular and cauliflower surface morphologies were plated separately on the graphite electrodes (GEs). The surface structure of samples was investigated by scanning electron microscopy (SEM) and their elemental analysis was done with electrode dispersive energy analysis (EDS). Then these modified electrodes were used as the anode for methanol oxidation reaction (MOR) in alkaline solution. Electrochemical studies were accomplished with cyclic voltammetry (CV) and chronoamperometry (CA) methods. Studies have shown, these different structures make a difference in the electrocatalytic performance of the electrodes and the highest methanol oxidation efficiency is related to Ni-B electrode with granular morphology. In order to reveal the methanol oxidation mechanism, coordination of anodic and cathodic peaks in CV diagrams was studied. Based on the results, we have offered the mechanism proposed by Fleischmann et al.

Battery graphite rod was modified with Ni nanoparticles with a new electroless procedure and the performance of the proposed electrode was evaluated as a non-enzymatic anode for electrocatalytic oxidation of glucose in alkaline media. Glucose fuel cells that useenzymes or microorganisms catalysts are limited by their extremely low power output andrather short durability. The structure and morphology of the electrode surface were examined with X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX) and scanning electron microscopy (SEM) techniques. Voltammetric and amperometric studies indicated that the onset potential of the glucose oxidation is low (~ 0.3 V) and the electrode stability is good. In addition to these advantageous, due to easily preparation and low cost, it will be used probably in glucose fuel cells as an anode.