Studies Of Ordered Mesoporous Carbon Modified Eletrode And Its Composites And Their Applications In Electrochemical (bio) Sensors

Carbon materials, such as carbon nanotubes （CNTs）, carbon nanofibers （CNFs）,graphene and mesoporous carbon （MC）, have attracted considerable attention infundamental research and industrial applications due to their remarkable electrical,thermal and mechanical properties. The ordered mesoporous carbon （OMC） which wasfirst synthesized in1999is a kind of novel advanced carbon materials. Due to itsuniform and tailored pore structure, high specific surface area, large pore volume,chemical inertness and good conductivity, OMC is becoming particularly promisingin applications of adsorbents, energy storages and heterogeneous catalysis. Recently,increasing attention has been focused on the electrochemistry and electrocatalysis ofOMC and its composites as advanced electrode materials. In this work, we havediscussed the synthesis and electrocatalytic performance of OMC-based compositematerials. This article mainly consists of the following several aspects：（1） A sensitive electrochemical sensor was developed to detect toxic ractopamineusing ordered mesoporus carbon modified glass carbon electrode （OMC/GCE）. Cyclicvoltammetry （CV） was used to investigate the electrochemical behaviors ofractopamine on OMC/GCE. The results indicated that the modified electroderemarkably enhanced electrocatalytic activity towards the oxidation of ractopaminewith a great increase of peak current. The oxidation mechanism was studied, and itwas deduced that the oxidation of ractopamine occurred at two phenolic hydroxylgroups, involving two protons and two electrons. Moreover, the influences ofaccumulation potential and time on the oxidation currents of ractopamine wereinvestigated. Under the optimum experimental conditions, differential pulsevoltammetry （DPV） was employed to the determination of ractopamine, with adetection limit of0.06μM （S/N=3）. Finally, the method was successfully applied forthe determination of ractopamine in pork samples with satisfying results.（2） A novel ordered mesoporous carbon/nickel oxide nanocomposite （OMC–NiO）was easily synthesized by carbonization of sucrose in the presence of nickel acetateinside SBA-15mesoporous silica template. After encapsulating nickel oxidenanoparticles in the wall of the ordered mesoporous carbon，the mesostructure of thenanocomposite material remained highly ordered and intact. For the first time,OMC–NiO material was used to modify the glassy carbon electrode （GCE）, and the obtained OMC–NiO modified GCE showed better electrocatalytic properties towardsepinephrine （EP） compared to that seen at OMC/GCE. The electrochemical behaviorof EP on the modified electrode was explored with cyclic voltammetry （CV） anddifferential pulse voltammetry （DPV）. Under the optimum condition，the oxidationpeak current obtained from DPV increased linearly with increasing EP concentrationsin the range of2.0×10^-7mol/L⁸.0×10^-5mol/L with a detection limit of3.8×10^-8mol/L （S/N=3）. Moreover, OMC–NiO modified GCE can be used for selectivedetermination of EP in the coexistence of a large amount of uric acide （UA）. Theelectrode has been applied to the assay of EP injection with satisfactory results.（3） A novel H₂O₂biosensor was developed by co-immobilizing hemoglobin （Hb）with ordered mesoporous carbon （OMC） enhanced AuNPs supported on quaternizedcellulose chains （Au@QC） and ioniclic liquids1-butyl-3-methylimidazoliumtetrafluoroborate （BMIMBF₄） film. Au@QC and BMIMBF₄could provide abiocompatible microenvironment for Hb and OMC could accelerate the electrontransfer between Hb and the electrode. The biosensor was examined by usingelectrochemical impedance spectroscopy （EIS） and cyclic voltammetry （CV）.Theresults indicated that Hb remained its bioactivity on the modified electrode,showing a couple of well-defined and quasi-reversible redox peaks, corresponding toHb FeⅢ/FeⅡcouple. Based on a series of optimized conditions, the films modifiedelectrode displayed a good electrocatalytic activity to the reduction of H₂O₂, whichhad linear current response from0.49to61.68μM with the detection limit of0.068μM （S/N=3）. The Hb/Au@QC-BMIMBF₄/OMC composites film modified electrodeshows a good sensitivity, reproducibility, excellent stability and wide linear range toH₂O₂, which makes a promising application of the preparation of third-generationH₂O₂biosensor.