Self-assembly Of Metal Ion Ultrathin Layer On Electrode Surface For Non-enzymatic Glucose Sensing

Glucose sensors are widely used in the fields of food,clinical,environmental,biological,and other applications.Not only there are strict controls on the glucose content in food industry,but also the human blood glucose levels are so important.The development of glucose sensors with high efficiency and good usability is so necessary.There are two kinds of glucose sensors: enzyme glucose sensor and non-enzymatic glucose sensor.Although enzyme glucose sensors have appeared for 40 years,due to their instability and inactivation,they have not widely used in industry.In contrast,non-enzymatic glucose sensors with high sensitivity,well selectivity and other good abilities have attracted more and more attention.According to the literatures,there is a great difference for some mental between its surface and bulk material properties in which the surfaces are much better metals than the bulk.Simultaneously,there are also some special properties for combined mental.If these features can be applied to the preparation of the electrode,improve the catalytic efficiency,catalytic mechanism and other aspects,obtained sensor would show very good performance.The main results obtained are as follows:1.Self-assembly of Ni ion ultrathin layer on electrode surface were studied.The ultrathin layer of Ni was obtained by the simple self-adsorption of Ni2+ on the surface of glass carbon electrode(GCE).Through a consecutive potential scan in alkali solution,the adsorbed Ni2+ was transformed to the ultrathin layer of Ni(OH)2/NiOOH which exhibits good electrocatalysis toward the oxidation of glucose.Only a little of Ni2+ was consumed to obtain such an ultrathin layer of Ni with excellent electrochemical performance.The adsorption method is very simple and the ultrathin layer of Ni was formed in a controllable manner with the size lower than nanoscale,which will find the application on nanofabrication for the nanodevices of fuel cell or electrochemical sensor in the future.2.Self-assembly of Bi ion ultrathin layer on electrode surface were studied.Bismuth has been attracting extensive interest in recent decades due to its unique properties.Especially,there is a great difference for bismuth between its surface and bulk material properties in which the surfaces are much better metals than the bulk.A submonolayer of bismuth was adsorbed onto platinum electrode surface by simple self-assembly.The obtained BiIII-Pt electrode exhibits two greatly increased oxidation peaks at negative and positive potential area respectively compared with platinum electrode alone,where Bi0 or BiIII trends to absorb more more OH-to be shared by the below adjacent platinum atom to form a structure of Pt-OH with high electrocatalytical activity.The BiIII-Pt electrode gives high sensitivity and excellent linearship of non-enzymatic glucose sensing,showing potential application for fuel cell,electrocatalysis and electroanalysis.3.Self-assembly of Bi ion ultrathin layer on platinum nanoparticles surface were studied.Using glucose as dispersant,well-dispersed and approximate icosahedron platinum nanoparticles(Pt NPs)with average size of about 6 nm were prepared by reducing K2PtCl4 with NaBH4.They were characterized with UV-Vis spectra(UV-Vis),transmission electron microscopy(TEM),energy dispersive X-ray(EDX),contact angle and electrochemical measurements.The obtained Pt NPs have good dispersibility and uniformity,exhibiting excellent electrochemical performance,showing the potential application in electrochemical sensing or fuel cell.The nanocomposites of BiIII/Pt nanoparticle(nanoPt)were prepared by a simple method where BiIII was self-adsorbed onto the surface of nanoPts to form a submonolayer due to the well known adsorption interaction between BiIII and Pt.The adsorption of BiIII on Pt NPs was confirmed by electrochemical studies.Without Pt NPs,BiIII wasn't adsorbed directly on the surface of glass carbon electrode(GCE).In the presence of NPs,the obtained nanocomposites of BiIII/nanoPt exhibit greatly increased electrocatalysis toward the oxidation of glucose compared with nanoPt alone.On the one hand,the existence of bismuth elements trends to adsorb more OH-in alkaline solution to form hydroxyl which may be shared by the below adjacent platinum atom to increase the amount of hydroxylated Pt which is the active specie for the electrochemical oxidation of glucose.On the other hand,Bi helps the cross linking of nanoPts and thus leads to more nanoPts immobilized on the surface of GCE.The prepared nanocomposites of BiIII/ nanoPt show the potential application in the areas of electrocatalysis or electroanalysis.