Application Of Electrochemical Sensing Based On Graphene Nanocomposites

Graphene is a new kind of carbon material with honeycomb lattice structure.It has large specific surface area,excellent conductivity and good chemical stability.Many excellent electrochemical sensors can be constructed by utilizing these unique properties of graphene.Moreover,graphene is an ideal substrate material,combing graphene with other materials can effectively improve the selectivity,sensitivity,stability and reproducibility of electrochemical sensor through the synergistic effect of various components.In this paper,three kinds of graphene-based nanocomposites were synthesized by combining conductive polymers,gold nanoparticles and graphene to construct electrochemical sensors for electrochemical detection of small biological molecules,environmental pollutants and drugs.The main work includes:(1)An efficient and eco-friendly ultraviolet irradiation method was developed to synthesize a ternary nanocomposite of gold-polyindole-reduced graphene oxide(AuPIn-RGO),and the nanomaterial was then used to fabricate an electrochemical sensor toward caffeine(CAF).The morphology,chemical composition and structure of AuPIn-RGO nanocomposite was studied by various characterization techniques.The electrochemical behavior of the composite and its electrocatalytic activity for CAF was also investigated.Due to the unique properties and synergistic effects of different components,the sensor exhibits a wide linear range(0.8-40 μM,40-1000 μM)and a low detection limit(0.26 μM),and has been successfully applied to the determination of CAF in practical samples.(2)A facile method was employed to develop gold nanoparticles/8-aminoquinoline functionalized graphene oxide(AuNPs/GAQ)composite.8-aminoquinoline was covalently bound to the edge of graphene oxide by amide reaction,and then gold nanoparticles were uniformly loaded on the surface of functionalized graphene oxide by electrostatic bonding to obtain AuNPs/GAQ nanocomposite.Based on this nanocomposite,a novel electrochemical sensor was developed for the determination of paraquat(PQ),a highly toxic herbicide.Due to the synergistic effect of AuNPs,8-AQ and GO,the modified electrode exhibits a wide linear range(0.02-24 μM)and a low detection limit(6 nM),and has been successfully applied to determine PQ in real water samples.(3)The nitrogen sulfur co-doped reduced graphene oxide(NS-rGO)was synthesized by one-step solvent thermal method and mixed with Au NPs to obtain Au NPs-NS-rGO nanocomposite,which was used for the electrochemical detection of rutin.The combination of N,S double doping and Au NPs can not only accelerate charge transfer,but also introduce more defects as active sites.Therefore,the Au NPs-NS-rGO exhibited a better electrocatalytic activity than N-rGO or S-rGO alone.The modified electrode showes a wide linear range of 0.2 nM-1.4 μM and a low detection limit of 0.067 nM.The method has been applied to the determination of rutin in tablets with satisfactory results.