| As the thinnest two-dimensional nanomaterial,graphene has been widely used to prepare various functional nanocomposites owing to large specific surface area,excellent electrical conductivity and electron mobility.Noble metal nanoparticles combine the qualities of metal materials and nanomaterials,exhibiting excellent electrocatalytic property and electrical conductivity.Incorporating graphene with noble metal nanoparticles can acquire a variety of nanocomposites with preeminent electrocatalytic performance.Hereby,it can be expected to improve the sensitivity of sensors by applying graphene/noble metal nanocomposites.Based on the particular properties of graphene,this dissertation briefly synthesized three graphene-based noble metal composites,which exhibited excellent catalytic activity,high sensitivity and good selectivity in electrochemical sensors.The specific works are as follows:1.Electrochemical sensor for facile detection of trace luteolin based on thio-?-cyclodextrin functionalized graphene/gold nanoparticles hybridsIn this work,a simple and highly sensitive electrochemical method was developed to detect luteolin based on thio-?-cyclodextrin functionalized graphene/goldnanoparticlesmodifiedglassycarbonelectrode?AuNPs/SH-?-CD-Gr/GCE?.The peak currents of luteolin on the AuNPs/SH-?-CD-Gr/GCE can be greatly enhanced compared to the SH-?-CD-Gr/GCE and the bare GCE.It suggests that the nanocomposite not only shows the excellent electrical properties of Gr and AuNPs but also exhibits higher enrichment ability of cyclodextrins via the host-guest interactionbetweencyclodextrinandluteolin.Atthe AuNPs/SH-?-CD-Gr/GCE,the peak currents increased linearly with the concentration of luteolin in the range of 1.0×10-11 mol/L to 1.0×10-5 mol/L.The detection limit was estimated to be 3.3×10-12 mol/L?S/N=3?,which was more sensitive or comparable with the previous electrochemical sensors for luteolin detection.The analytical performance of this sensor has been evaluated for the detection of luteolin in human serum with satisfactory results.Furthermore,the method might open up a new possibility by using the nanohybrids to monitor other flavonoids which can form host-guest complexes with cyclodextrins.2.Electrochemical sensor for sensitive detection of triclosan and triclocarban based on graphene/palladium nanoparticles hybridsHerein,poly?diallyldimethylammonium chloride?functionalized graphene/palladium nanoparticles?PDDA-Gr/PdNPs?have been successfully synthesized through a simple one-pot method with the use of PDDA as stabilizing agents.Then,the nanocomposites of PDDA-Gr/PdNPs were characterized by techniques of UV-vis absorption spectrum?UV-vis?,transmission electron microscope?TEM?,X-ray photoelectron spectroscopy?XPS?,cyclic voltammetry?CV?and electrochemical impedance?EIS?.The electrochemical response of triclosan and triclocarban on the PDDA-Gr/PdNPs modified glassy carbon electrode?GCE?is greatly enhanced comparing to the PDDA-Gr/GCE or the bare GCE.It is suggested that the nanocomposite exhibited good electron transfer ability and catalytic activity.Under the optimal conditions,the linear responses of triclosan and triclocarban were in the concentration ranges of 9.0×10-9 mol/L2.0×10-5mol/L and 1.0×10-8 mol/L2.0×10-5 mol/L with the detection limits of 3.5×10-9 mol/L and 3.0×10-9 mol/L?S/N=3?,respectively.Besides,the electrochemical sensor presented superior reproducibility,excellent anti-interference performance and long-term stability.What is more,the method is promising for the determination of trace amounts of triclosan and triclocarban in water samples.3.Rapid electrochemical detection of sunset yellow and tartrazine based on graphene-gold nanocompositeIn this chapter,PDDA-Gr/AuNPs nanocomposite were synthesized facilely by simple hydrothermal method.Based on PDDA-Gr/AuNPs,an electrochemical sensor was constructed for the simultaneous determination of Sunset yellow?SY?and Tartrazine?TZ?.In the presence of constant concentration of Tz or SY,the linear ranges of sunset yellow and tartrazine were 6.0×10-9 mol/L to 5.0×10-6 mol/L and 8.0×10-9 mol/L to 3.0×10-6mol/L,respectively.The detection limits were 2.0×10-9 mol/L and 2.5×10-9mol/L?S/N=3?,respectively.The method showed high accuracy,good reproducibility and strong anti-interference abilities.The sensor was also used to determine the concentration of SY and Tz in common drinks and the recovery was from 92.6%to 108.0%.These results showed the new sensor would provide a good platform for routine determination of azo dyes in future. |
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