Construction And Application Of Electrochemical Sensor Based On ZnO Arrays

Design and fabrication new type chemical modified electrodes and their based electrochemicalsensors with ultrahigh sensitivity and excellent selectivity are the hot topics for analytical chemistry researchers in both china and abroad.With the vigorous developpment of nanotechnology as well as materials science,biochemistry and polymer science,kinds of functional nanomasterials emerging in endlessly.Meanwhile,these nanomaterials are widely used in electrode modification,thus their based electrochemical sensors with different function and structured have been proposed rapidly.In recent years,electrochemical sensor based on the nanomaterials arrays has been attractingwide attention of researchers.Electrochemical sensor based on nanomaterials arrays can make full use of the surface area for loading more recognition sites,which can improve the sensitivity and selectivity of the prepared electrochemical sensors.At present,carbon nanotube,zinc oxide nanorods?nanotubes?,titanium oxide nanorods?nanotubes?have been widely used to construct different electrochemical sensors.Due to the rich source and easy preparation nature,ZnO nanorods?nanotubes?were choosed as support for preparation modified electrode in our work.Vertical ZnO nanorods?nanotubes?were successfully obtained by adjusting the electrodeposition paramters.In this dissertation,two types high performance electrochemical sensor for dopamine were fabricated based on ZnO arrays?nanorods or nanotubes?.The dissertation is designed according to the following ideas:?1?Vertical zinc oxide nanorods?ZNRs?with proper density were synthesized onto indium tinoxide coated polyethylene terephthalate?ITO/PET?film via one step seed-free electrodeposition by using Zn?NO₃?₂,HMT,KCl and trace AlCl₃ as starting reagents.The density and perpendicularity of ZNRs have great influence on fabricating high performance electrochemical sensor.So,we mainly discussed the influencing factor for ZNRs electrodeposition:such as concentration of reactants,electrodeposition potential and time.Finally,the optimal electrodeposition parameters were set as 0.2 mM?reactant concentration?,-1 V?electrodeposition potential?and 40 min?electrodeposition time?.Vertically ZNRs arrays sensitized with gold nanoparticles?GNPs?were designed and fabricated onto ITO/PET film for dopamine electrochemical sensing.GNPs that possess excellent electrocatalytic activity towards target were decorated onto the ZNRs via one-step electrodeposition by cyclic voltammetry.These gold nanoparticles sensitized vertically ZnO nanorods arrays?GNPs/ZNRs?combine the advantages of GNPs and ZNRs,thus providing chance to develop electrochemical sensors with ultrahigh sensitivity and excellent selectivity.When used for dopamine electrochemical sensing,the fabricated electrochemical sensor shows wide linear dynamic range?10 nM-800?M?and has good accuracy for dopamine determination in real biological samples.?2?Vertical aligned ZNTs arrays were prepared via a two-step process.First,ZNRs arrays werefabricated onto FTO glass by electrodeposition using the mentioned experiment condition.Then,ZNRs arrays were undergone chemical etching for morphology transformation in KOH aqueous solution?0.125M,70°C and 20 min?.ZNTs arrays was obtained after rinsed with flowing deionized water and then blown dry with nitrogen gas.The ZNTs arrays were used as supports for molecularly imprinted polymers?MIPs?arrays fabrication.Using dopamine as template molecule,pyrrole as functional monomer and crosslinker,ZNTs supported MIPs?ZNTs-MIPs?arrays were prepared by cyclic voltammetry.After extracting embedded dopamine from MIPs arrays in phosphate buffer solution,ZNTs supported MIPs?ZNTs-MIPs?arrays based electrochemical sensor for dopamine was obtained.Due to the imprinted cavities are always located at inner and outer surface of ZNTs,these ZNTs supported MIPs?ZNTs-MIPs?arrays have good accessibility towards template.All described above are beneficial for fabricating MIPs based electrochemical sensor with high sensitivity,high selectivity and fast response.The performance of ZNTs-MIPs based electrochemical sensor was characterized using K₃[Fe?CN?₆]as electron probe.The fabricated electrochemical sensor shows wide linear dynamic range?20 nM-800?M?towards dopamine and has good accuracy for dopamine determination.