The graphene nanopowder for electro-catalytic oxidation of dopamine and uric acid in the presence of ascorbic acid

The graphene nanopowder for electro-catalytic oxidation of dopamine and uric acid in the presence of ascorbic acid has been investigated by cyclic voltammetry,linear polarization and chronoamperometry.The graphene nanopowder modified electrode was prepared using the drop coating method,which displayed excellent electrocatalytic activity towards the oxidation of dopamine and uric acid compared with the bare glassy carbon electrode in phosphate buffer solution at pH=7.0.Linear responses for dopamine and uric acid were obtained in the ranges of3.3μmol/L to 249.1μmol/L and 6.7μmol/L to 386.3μmol/L with detection limits of 1.5μmol/L and 2.7μmol/L(S/N=3),respectively.The response time was less than 2 s in case of dopamine and 3 s in case of uric acid,respectively.The results demonstrated that the graphene nanopowder had potential for detecting dopamine and uric acid.

Electro-catalytic degradation of sulfisoxazole by using graphene anode

Graphite and graphene electrodes were prepared by using pure graphite as precursor. The electrode materials were characterized by a scanning electron microscope（SEM）, X-ray diffraction（XRD） and cyclic voltammetry（CV） measurements. The electro-catalytic activity for degradation of sulfisoxazole（SIZ） was investigated by using prepared graphene or graphite anode. The results showed that the degradation of SIZ was much more rapid on the graphene than that on the graphite electrode. Moreover, the graphene electrode exhibited good stability and recyclability. The analysis on the intermediate products and the measurement of active species during the SIZ degradation demonstrated that indirect oxidation is the dominant mechanism, involving the electro-catalytic generation of OH and O_2^- as the main active oxygen species. This study implies that graphene is a promising potential electrode material for long-term application to electro-catalytic degradation of organic pollutants.

Electrocatalytic oxidation of hydrazine with alizarin red S as a homogenous mediator on the glassy carbon electrode

Electro-catalytic oxidation and detection of hydrazine on a glassy carbon electrode,at pH 6.0,was studied by using alizarin red S as a homogeneous mediator.The overall number of electrons involved in the catalytic oxidation of hydrazine and that involved in the rate-determining step were four and one,respectively.The interfering effect of some cations,anions and organic compounds were examined.Peak current for this process varied linearly with the square root of the scan rate.The kinetic parameters,such as the electron transfer coefficient(α) and catalytic rate constant(k) ,were determined using cyclic voltammetry,linear sweep voltammetry and chronoamperometry.The electro-catalytic response was optimized with regards to the pH,scan rate,hydrazine concentration and other variables.

Towards High-performance Lithium-Sulfur Batteries: the Modification of Polypropylene Separator by 3D Porous Carbon Structure Embedded with Fe3C/Fe Nanoparticles

Lithium-sulfur(Li-S)batteries with high energy densities have received increasing attention.However,the electrochemical performance of Li-S batteries is still far from the satisfactory of the practical application,which can be mainly attributed to the shuttling of polysulfides and the slow reaction kinetics of polysulfide conversion.To address this issue,a 3D porous carbon structure constructed by 2D N-doped graphene and 1D carbon nanotubes with embedded Fe3C/Fe nanoparticles(NG@Fe3C/Fe)was designed and prepared by a simple programmed calcination method for the modification of polypropylene(PP)separator.The Fe3C/Fe nanoparticles demonstrate an excellent catalytic conversion and strong chemisorption towards polysulfides,while the unique architecture of N-doped graphene promotes the Li+/electron transfer and the physical adsorption of polysulfides.The electrochemical performance of the Li-S batteries with the NG@Fe3C/Fe-modified separator is significantly improved.A large discharge capacity of 1481 mA∙h∙g-1 is achieved at 0.2 C(1 C=1675 mA/g),and a high capacity of 601 mA∙h∙g-1 is maintained after discharged/charged for 500 cycles at a current rate of 1 C.This work provides a new approach for the development of high-performance Li-S batteries through the modification of the PP separator by rationally designed composites with large adsorption capability to polysulfides,good wettability to the electrolyte and high catalytic property.

Poly(Dimethylbenzimidazolium) Iodide Assisted Dispersion of Multiwalled Carbon Nanotubes and Their Palladium Nanoparticle Hybrid

The multi walled carbon nanotubes(MWNTs) have always been as the catalyst supporting materials,but for high-performance composite catalysts, the dispersion and functionalization of MWNTs are important challenging problems. In this paper, Electrocatalytically active palladium nanoparticles(Pd NPs) on MWNTs with the high-performance and excellent solubility polymer, poly(dimethylbenzimidazolium) iodide(P(DMBI)-I-)as modifier and glue was first discussed. The results of transmission electron microscopy(TEM) demonstrate a better dispersion of MWNTs with the assist of P(DMBI)-I-. The Raman spectra indicate a strong π-π interaction between MWNTs and P(DMBI)-I-. Taking advantages of the coordination effect of imidazole groups and the electrostatic attraction to Pd NPs, the prepared Pd/MWNTs-P(DMBI)-I-(Pd/MPDI-) hybrid is of well electrocatalytic activity to the ethanol fuel cells by electrochemical measurements. So it is believed that P(DMBI)-Ican be further applied in the dispersion of different carbon-based materials and metal nanoparticles for fabricating more novel composites for catalyst and electrode material.