Preparation Of Graphene Nanocomposites And Their Applications In Electrochemical Sensors

The thesis mainly focuses on the synthesis of several electrochemical biosensors, including rGO-SWCNT-Au/GCE biosensors for glucose sensing, NG-Au@Ag/GCE biosensors for daunorubicin (DNR) detecting and NG-AgAu/GCE sensors for Cu2+ sensing. Techniques such as high-resolution transmission electron micrographs (HR-TEM), TEM, SEM, UV-Vis, XRD and XPS were used to characterize the obtained nanocomposites.1. One-pot preparation of reduced graphene oxide-carbon nanotube decorated with Au nanoparticles based on protein for non-enzymatic electrochemical sensing of glucoseA simple one-pot reduction/decoration strategy was reported to produce Au nanoparticles (NPs) dotted three-dimensional (3D) porous reduced graphene oxide-single walled carbon nanotube (rGO-SWCNT-Au) nanocomposites. In the synthesis process, GO was used to disperse SWCNT and the obtained GO-SWCNT conjugate was used as supporting material to further disperse in situ growing Au NPs. Bovine serum albumin (BSA) was used as both reducing and stabilizing agent to reduce GO and HAuCl4 and to stabilize rGO-SWCNT and Au NPs. The morphology and microstructure characterization revealed that the proposed method could lead to the simultaneous reduction of GO and HAuCl4 together with efficient dispersion of Au NPs on the surface of rGO-SWCNT. Furthermore, electrochemical experiments demonstrated that rGO-SWCNT-Au nanocomposites could be used as electrocatalysts towards the oxidation of glucose, a linear response to a concentration range of 0.00001-80 mM and a detection limit of 2.2 nM (S/N=3) were achieved.2. Facile synthesis of nitrogen-doped reduced graphene oxide supported Au@Ag nanospheres with enhanced electrocatalytic activity for daunorubicin determinationHerein, we report on a simply strategy to produce Au@Ag nanoparticles (NPs) dotted nitrogen-doped graphene nanocomposites (i.e., NG-Au@Ag). In the synthesis process, one-pot reduction/decoration strategy to produce Au NPs dotted nitrogen-doped graphene hybrid (i.e., NG-Au) by hydrothermal rout with (NHO2CO3 as reducing-doping agents. The as-obtained NG-Au hybrid is used as supporting material to further disperse in situ growing Au@Ag NPs. We have investigated its TEM?XPS and XRD properties. Most importantly, the resulting nanocomposite modified electrode have good performance in sensing DNR. Under the optimized conditions, a linear response to a concentration range of 0.01 ?g mL-1-15 ?g mL-1 and a detection limit of 3 ng mL-1 (S/N=3) were achieved. The linear equation was Ipc (?A) =4.84+6.794c (?g mL-1) (R=0.994). The sensor was successfully applied to the determination of DNR in human serum.3. Facile preparation of AgAu bimetallic alloy nanoparticles decoration nitrogen-doped graphene hybrid nanostructure for electrochemical sensing of Cu2+Herein, we report on a simply strategy to produce AgAu nanoparticles (NPs) dotted nitrogen-doped graphene nanocomposites (i.e., NG-AgAu). In the synthesis process, a facile strategy to produce Ag NPs dotted GO hybrid (i.e., GO-Au) by ultrasonic heating. The as-obtained GO-Au hybrid were further reduction/decoration by hydrothermal rout with (NH4)2CO3 as reducing-doping agents to produce AgAu NPs dotted nitrogen-doped graphene hybrid (i.e., NG-AgAu). We have investigated its TEM?XPS and XRD properties. Furthermore, we developed a electrochemical sensor for the detection of Cu2+used the obtained NG-AgAu hybrid, according to copper-catalyzed oxidation of L-cysteamine (L-Cys). Under the optimized conditions, a linear response to a concentration range of 1 nM-1×106 nM and a detection limit of 0.3 nM (S/N=3) were achieved. The linear equation was Jpa (?A)=0.7055+0.015c (nM) (R=0.998). The sensor was successfully applied to the determination of Cu2+in river water.