Acid-modified Carbon Nanotubes Research Articles

Multi-wall carbon nanotubes as a sensor and ferrocene dicarboxylic acid as a mediator for voltammetric determination of glutathione in hemolysed erythrocyte

A sensitive and selective electrochemical method was developed for determination of glutathione (GSH) in hemolysed erythrocyte using a ferrocene dicarboxylic acid modified carbon nanotubes paste electrode (FDCCNTPE). Cyclic voltammetry (CV), double potential-step chronoamperometry and differential pulse voltammetric (DPV) were used to investigate the suitability of ferrocene dicarboxylic acid at the surface of a multi-wall carbon nanotubes paste electrode as a mediator for the electrocatalytic oxidation of glutathione in aqueous solutions with various pH. The results showed that FDCCNTPE had high electrocatalytic activity for the electrooxidation of glutathione. Under optimum conditions (pH 7.00), oxidation of GSH occurs at a potential about 230 mV less positive than that at the unmodified carbon nanotubes paste electrode. The catalytic reaction rate constant, kh was calculated (1.98 × 104 M−1 s−1) using chronoamperometry. The electrocatalytic oxidation peak current of GSH showed two linear dynamic ranges with a detection limit of 0.2 μmol L−1 GSH. The linear calibration ranges were obtained between 0.5–24 μmol L−1 and 24–122 μmol L−1 GSH using the DPV method. Finally, the proposed method was also examined as a selective, simple and precise electrochemical sensor for the determination of GSH in real samples such as hemolysed erythrocyte.

Sensitive and Selective Determination of Phenylhydrazine in the Presence of Hydrazine at a Ferrocene Monocarboxylic Acid Modified Carbon Nanotube Paste Electrode

In the present paper, the use of a carbon paste electrode modified by ferrocene monocarboxylic acid (FMC) and carbon nanotubes prepared by a simple and rapid method was described. The modified electrode showed an excellent character for electrocatalytic oxidization of phenylhydrazine (PHZ) and hydrazine (HZ) with a 300 mV separation of both peaks. Differential pulse voltammetric peak currents of PHZ and HZ increased linearly with their concentrations at the range of 0.8 µM to 700 µM and 16 µM to 800 µM and the detection limits (3σ) were determined to be 0.42 µM and 14 µM, respectively.

Carbon nanotube capsules encapsulating SnO 2 nanoparticles as an anode material for lithium ion batteries

Carbon nanotubes capsules (CNCs) with compact, stout walls and tunable sizes were fabricated by using self-assembly of acid modified carbon nanotubes in a water-in-oil emulsion system. The effect of ultrasonic power on the formation and size of CNCs were investigated. On the basis of fabrication of CNCs, CNCs encapsulating SnO 2 nanoparticles were prepared as anode material for lithium ion batteries. The morphologies, structural characteristics and electrochemical performances of CNCs and CNCs encapsulating SnO 2 nanoparticles were systemically investigated by FE-SEM, TEM, XRD and a series of electrochemical testing techniques. The results showed that the encapsulation amount of SnO 2 in CNCs had a great influence on the reversible capacity and cycle performance of the composites. The composite with appropriate amount of SnO 2 exhibited a high reversible capacity of 383 mAh g −1 and an excellent cyclability with only 0.4% capacity loss/cycle in that CNCs not only could provide high electric conductivity for composites but also effectively accommodate the volume change of SnO 2 during the cycling processes.

Preparation and characterization of sulfonic acid-functionalized single-walled carbon nanotubes

A strategy for the functionalization of single-walled carbon nanotubes is reported. The synthesis involved the conversion of fluorinated single-walled carbon nanotubes to the thiolated derivative assisted by phosphorous pentasulfide. The thiol group is then quantitatively oxidized to the sulfonic acid group. The extent of oxidation of the thiol precursor is confirmed using X-ray photoelectron spectroscopy, which proved to be immensely useful to discriminate between the –SH and –SO 3H with a chemical shift for the sulfur 2p (approx. 5 eV). The functionalized carbon nanotubes were further characterized by infrared spectroscopy, thermogravimetric analysis, and transmission electron microscopy which revealed a significant change in morphology between the fluoro carbon nanotubes, the thiol and sulfonic acid-modified carbon nanotubes.