Study Of The Electrochemical Sensor Based On Noble Mental Doped Nanomaterials

In recent years, carbon nanomaterials(graphene, CNTs, fullerene, CNFs) have attracted tremendous research interest in the field of electrochemistry, especially for graphene and CNTs, which are probably the most important for a myriad of potential next generation devices, owing to their intrinsic properties, including the electronic, optical, and mechanical properties associated with their structure.Moreover, noble metal nanoparticles have emerged as promising materials recently and showed inspiring potentials in sensing owning to their unusual physicaland chemical properties. The marriage of carbon nanomaterials and noble nanoparticles electrochemical sensors has created many ingenious sensing strategies for applications in the areas of clinical diagnosis and food safety. This thesis paid special attention to electrochemical sensors based on noble mental doped carbon nanomaterials. It includes five sections as follows:(1) The preparation and electrochemical sensor activity of Pd/Graphite nanocomposite: The graphite-supported palladium(Pd/Grp) nanocomposite modified glassy carbon(GC) electrode was fabricated and their catalytic properties towards nitrite were studied. Pd/Grp was synthesized by microwave-assisted hydrogen reduction of palladium(II) acetate with graphite power. TEM displayed a high density of slightly aggregated Pd nanoparticles loading on the surface of graphite powder with a diameter of 5–15 nm. The electrode exhibits enhanced electrocatalytic behavior to the oxidation of nitrite compared to the activated carbon-supported palladium and SiO2-supported palladium modified GC electrode. The palladium nanoparticles supported on different substrates were investigated by XPS spectra and the effects of substrates were discussed. Under the optimal conditions, The Pd/Grp modified GC electrode can be used to determine nitrite concentration in a wide linear range of 0.3 and 50.7 ?M and a limit of detection of 0.071 ?M at a signal-to-noise ratio = 3(S/N = 3).The sensitivity of the electrode was0.29 ?A?M-1cm-2.(2) The preparation and study of the electrochemical activity of Pd/CNTs: A novel chemically modified electrode is constructed based on the carbon nanotubes-supported Pd nanoparticles(Pd/CNTs). It is demonstrated that the sensor can be used for the determination of dopamine(DA) and paracetamol(PA).The measurements were carried out by the application of cyclic voltammetry(CV), differential pulsevoltammetry(DPV) and amperometric i-t curve. Under the optimum conditions, the modified electrode provides a linear response versus dopamine concentrations in the range of 0.3-50 ?M and PA concentrations in the range of 0.2-60 ?M, respectively using the amperometric i-t curve method. The detection limits for DA and PA were 91 ?M and 89 ?M(S/N=3), respectively. The sensitivity of the electrode was 0.928 and 1.532 ?A ?M-1 cm-1, respectively.(3) The preparation of Au-Pd/CNTs nanocomposite as well as its electrochemical activity: A novel nanocomposite consisting of Au-Pd bimetallic nanoparticles supported on carbon nanotubes(Au-Pd/CNTs) have been fabricated for nonenzymatic detection of the neurotransmitter dopamine(DA).The Au-Pd/CNTs based electrode show excellent selective electrochemical activity towards dopamine in the presence of ascorbic acid(AA) at pH 7.0. Amperometric i-t curve shows that the Au-Pd/CNTs sensor exhibits a linear response over a wide concentration range from 0.2 to 50 ?M of DA with the lowest detection limit of 83 nM(S/N=3). Furthermore, the developed sensor was applied to determine DA concentrations in bovine serum which indicated that it could be effectively used for real sample analysis.(4) The preparation of PdPc-CNTs nanocomposite as well as its electrochemical activity: Here we report, an easy, straightforward and novel way to prepare the palladium phthalocyanine-CNTs(PdPc-CNTs)nanocomposite for rutin detection. Electrochemical characterization shows that the PdPc-CNTs-Nafion composite modified GCE has a high electrochemical sensing activity towards rutin, with a fast response less than3 s, a wide linear range of 0.1–51?M, and a low detection limit of 0.075 ?M.The electrochemical sensor exhibited good stability, precision, and few interferences.(5)The preparation of Au-PDDA-HCNTs nanocomposite as well as its electrochemical activity:Poly(diallyldimethylammonium chloride) functionalized helical carbon nanotubes(PDDA-HCNTs) were successfully synthesized, and gold nanoparticles(AuNPs) were successfully assembled on the surface of HCNTs via a self-assembly approach. The resulting Au-PDDA-HCNTs were characterized and expected to offer a promising material for rutin detection because of its satisfactory chemical stability and the good biocompatibility of AuNPs. The i-t approach provided a linear response range between 0.1 and 30 ?M with a detection limit of 81 nM.