Research On Electrochemical Sensors Based On Modified Fibers Of Precious Metal Nanomaterials

With the fast development of nanotechnology and the continuing interest in the study of noble metal nanoparticles,the unique properties of noble metal nanoparticles have attracted the widespread attention.The nanomaterials have been widely applied in analytical application,catalysis,biological systems,corrosion science,and battery devices.The metal nanomaterials have expanded from the beginning of spherical nanoparticles to the various shapes of metal nano-cubes,nano-triangles,nano-stars,nanorods,nanoflakes and nano-disks.The size,shape,and composition of the nanomaterials are the key factors affecting the physical and chemical properties of nanomaterials.Among them,noble metal nanoparticles are quite outstanding because of their unique physical and chemical properties,including the large specific surface area,high surface energy,surface crystal defects,and the dual properties of metal essence and nanostructures.It is,however,found to be easy to aggregate and thus lose its novel properties,which really limits its practical applications.In order to overcome this weakness,nanotechnology has been used to create the nanocomposites by combining the noble metal nanoparticles with conductive polymers or non-metal materials,where the nanomaterials not only have the excellent performance of a single component material,but also provide the new functions for the materials.In this work,noble metal nanoparticles were modified on the polymer membrane substrate to avoid the agglomeration.The membranes include the electrospun polystyrene fiber membrane and the polyaniline?PANI?tube membrane fabricated from the template of polystyrene fiber membrane.The polystyrene was used due to its thermoplastic property and mechanical stability as well as its possibility of sulfonation and the capability to further modification with metal nanoparticles.While,polyaniline is of interest due to its high conductivity after acid-doping,large specific surface area,highly environmental and thermal stability,and redox characteristics as well as their potential applications of electrochemical sensors in analytical chemistry.The present work was designed and executed to modify the noble metal nanomaterials of gold,palladium and silver on the surface of the fiber membranes.The as-fabricated nanocomposite materials was deployed to analyze their electrochemical properties toward the detection of nitrite,glucose and hydrogen peroxide?H₂O₂?.The electrochemical sensors were also employed to perform the study in practical applications.This thesis is mainly divided into the following three aspects:?1?Gold nanoparticles modified polystyrene fiber membrane for the electrochemical detection of nitrite.The working electrode of Au/SPS/GCE was constructed through the electrospinning of polystyrene fiber and the following electrodeposition of gold nanoparticles?AuNPs?,and was then applied for the electrochemical study of nitrite detection.The results show that the linear response ranges of nitrite are 1?mol/L-5823?mol/L and 6281?mol/L-25307?mol/L,and the detection limit is 0.6?mol/L.The as-fabricated sensor shows the strong time stability,and is capable of detecting the low concentrations of nitrite in saliva of real samples.?2?Palladium nanoparticles modified polyaniline tube membrane for the electrochemical detection of glucose.A composite electrode of Pd/PANI/GCE was constructed by using the in-situ chemical deposition and the electrostatic spinning technology.The polyaniline was firstly modified on the surface of sulfonated polystyrene fiber membrane through the charge interaction between the positively charged aniline monomers and the sulfonated units,and the following polymerization.The polystyrene was extracted from the polystyrene@polyaniline composite fiber?SPS@PANI?by using the tetrahydrofuran?THF?to thus form the polyaniline hollow tube?PANI?membrane,which was then deposited with palladium nanoparticles?PdNPs?to form the catalytic composite membrane for the sensor fabrication.The as-fabricated glucose sensor shows the linear response ranges of 0.1?mol/L-44?mol/L and 44?mol/L-3423?mol/L,and the detection limit of 0.06?mol/L.The sensor has been applied to the detection of lower concentration glucose in saliva of real samples.?3?Silver nanoparticles modified polyaniline tube membrane for electrochemical detection of hydrogen peroxide.The silver nanoflower?AgNF?were deposited onto polyaniline tube substrate through the in-situ chemical reduction.The as-fabricated electrochemical sensor of Ag/PANI/GCE shows the good electrocatalytic performance toward the reduction of hydrogen peroxide.The concentration linearity range of 0.1?mol/L-3388?mol/L and the detection limit of 0.08?mol/L were achieved.