Synthesis And Electrochemical Applications Of Nano-Ag Particles-chitosan-graphene Composites

In this paper, Nano-Ag particles-chitosan-sulfonated graphene composites weresynthesized. The composites were characterized systematically by FT-IR, XRD,UV-VIS, TEM and Raman. Nano-Ag particles-chitosan-graphene composites wereapplied to modify electrode, then noenzymatic H2O2sensor was constructed and itsperformances were studied systematically.The main results were as follows:(1) AgNPs-CS (Nano-Ag particles-chitosan composites) were prepared by adop--tting in-situ reduction.Chitosan not only acted as the reducing agent for the silvernitrate, but also stabilized the Nano-Ag particles by anchoring them. Then we studiedthe effects of reaction time, reaction temperature, concentration of silver nitrate,concentration of chitosan, concentration ratio of silver nitrate and chitosan on thereaction. By optimizing the reaction conditions, spherical nano-Ag particles wereshowed in AgNPs-CS composites and nano-Ag particles disperse evenly on thesurface of chitosan with mean particle size under5nm.(2) GO (graphene oxide) was prepared by a modified Hummer’s method, Theprocess of synthesizing GS (sulfonated graphene) from GO consists of three steps:1)pre-reduction of graphene oxide with ascorbic acid;2) sulfonation with the aryldiazonium salt of sulfanilic acid; and3) post-reduction with sodium citrate.The GSwas characterized systematically, the results stated that sulfanilic successfully graftedonto the graphene. The prepared GS has smooth surface, transparent, clean andless-layers.(3) AgNPs-CS-GS (Nano-Ag particles-chitosan-sulfonated graphene) compositeswere formed by electrostatically-assembling between the positively charged chitosan--silver nanoparticle composites and negatively charged sulfonated graphene. Theresults showed that AgNPs-CS-GS is three-layer structure, chitosan played a role as’janus’, one side is used to load nano-Ag particles, and the other side is combinedsulfonated graphene by electrostatically-assembling. The particle size and dispersionof nano-Ag particles was not affected in the composite process.(4) AgNPs-CS-GS (Nano-Ag particles-chitosan-sulfonated graphene) compositeswere used to modify glassy carbon electrode directly to obtain a noenzymatic H2O2sensor. This noenzymatic H2O2sensor showed a fast amperometric response time of less than2s. In the range of0.1mM to10mM, the current response was linear to theH2O2concentration(r=0.998) and the detection limit was found to be4μΜ (S/N=3)...