The Investigation Of Nano Electrochemical Sensor Fabricated By Electrodeposition Based On Pyridylazo Amine Reagent-Metal Complex

Nanomaterials have unique physical and chemical properties which makes them of great application value in many fields.The application of nanomaterials in electrochemical sensing used for the determination of inorganic,organic and biological samples has become a hot topic in electroanalytical chemistry.Electrodeposition is an effective method for controllable preparation of nanomaterials.Sensors with high performance constructed by this technology greatly improved the sensitivity and selectivity of analysis and detection.Based on this,three kinds of electrochemical sensors based on nano-palladium,nano-cobalt and nano-copper were successfully constructed by cyclic voltammetry and potentiostatic electrodeposition with pyridylazo amine reagent-metal complex as electrodeposition precursor;The structure and properties of nanomaterials were characterized by Scanning electron microscopy(SEM),X-ray powder diffraction(XRD)and energy spectrum(EDS);new electrochemical methods for the sensitive determination of hydrazine hydrate(N2H4),nitrite(NO2-),formaldehyde(HCHO)and hydrogen peroxide(H2O2)were established.The details are as follows:1.The investigation of electrochemical sensing of nano-cobalt based on complexation regulation mechanism.(1)Co NPs-5-I-PADAT/GCE was fabricated by directly immersed glassy carbon electrode(GCE)into coordination compound of Co2+-5-I-PADAT(Co2+-5-I-PADAT+0.1M KCl)by cyclic voltammetry.The fabricating conditions of sensor were optimized and the electrocatalytic oxidation behavior of N2H4 was investigated.The results indicated that the involvement of 5-I-PADAT to the fabrication of nano-cobalt sensorCo NPs-5-I-PADAT/ITO,can increase the oxidative peak current of N2H4 2 times,and reduce the oxidative overpotential 0.25 V comparing with Co NPs/GCE.This electrochemical sensor showed linear range of 0.64 ?M ~ 2150 ?M with the detection limit of 0.28 ?M(S/N = 3);(2)A new chromogenic agent 5-2-(5-iodine-2-pyridine azo)-2-dimethyl amine aniline(5-I-PADMA)was modified on ITO glass electrodeto capture cobalt ions in the solution system.Then,Co2+ was reduced on the electrode in situ to prepare cobalt nopartides/ITO.The electrocatalytic oxidation behavior of this sensor towards N2H4 was investigated.The results indicated that the involvement of 5-I-PADM to the fabrication of nano-cobalt sensor Co NPs-5-I-PADMA/ITO.Compared with the pure cobalt metal sensor,the Co NPs-5-I-PADMA/ITO sensor has obvious advantage on the detection performance of N2H4.This electrochemical sensor showed linear range of 0.5 ?M ~ 4 m M.The sensor was used to determine N2H4 in real water samples and compared with ultraviolet spectrophotometry.The results are satisfactory;(3)Pd-Co NPs-5-Br-PADMA/ITO was fabricated by drip coating the mixture of palladium and cobalt ions complexated with 2-(5-bromo-2-pyridine azo)-5-dimethylaminidine(5-Br-PADMA)onto Indium tin oxide electrode(ITO)following cyclic voltammetry.The electrocatalytic reduction behavior of this sensor towards H2O2 was investigated.The results indicated that the sensor showed a good electrocatalytic reduction activity against H2O2 in 0.12 M Na OH solution.This electrochemical sensor showed linear range of 0.1 ?M ~ 2424 ?M with a detection limit of of 0.05 ?M(S/N = 3).2.The investigation of electrochemical sensing of nano-palladium based on complexation regulation mechanism.(1)Pd NPs-5-Br-PADMA/ITO was fabricated by directly immersed ITO into coordination compound of Pd2+-5-Br-PADMA(Pd2+-5-Br-PADMA+0.1 M KCl)following potentiostatic method.The fabricating conditions of sensor were optimized andthe electrocatalytic oxidation behavior of NO2-was investigated.The results indicated that the involvement of 5-Br-PADMA into the fabrication of nano-Palladium sensor Pd NPs-5-Br-PADMA/ITO,can increase the oxidative peak current of NO2-2 times.This electrochemical sensor showed linear range of 6.6 ?M ~ 890 ?M and 0.1 ?M ~ 6.6?M with the detection limit of 0.08 ?M(S/N = 3).Compared with other sensors,the sensor has the advantages of wide linear and low detection limit;(2)Pd NPs-5-CN-PADAT/ITO was fabricated by drip coating of the palladium ions complexated with 2-(5-bromo-2-pyridine azo)-5-dimethylaminidine(5-CN-PADAT)onto Indium tin oxide electrode(ITO)following cyclic voltammetry.The fabricating conditions of sensor were optimized and the electrocatalytic oxidation behavior of HCHO was investigated.This electrochemical sensor showed linear range of 5 ?M ~ 800?M with the detection limit of 2.8 ?M(S/N = 3).3.The Investigation of electrochemical sensing of nano-copper based on complexation regulation mechanism.Cu NPs-5-Br-PADMA/ITO was fabricated by drip coating complex of copper ions-2-(5-bromo-2-pyridylazo)-5-dimethylaminoaniline(5-Br-PADMA)onto ITO following cyclic voltammetry.The electrochemical sensors were characterized Scanning electron microscopy(SEM),X-ray powder diffraction(XRD),energy spectrum(EDS)and electrochemical methods used to investigate the electrocatalytic reduction behavior of H2O2.The results indicated that the sensor showed a preferable electrocatalytic reduction activity against H2O2 in p H = 7.0 PBS solution.This electrochemical sensor showed linear range of 2.5 ?M ~ 0.63 m M and the detection limit is 1 ?M(S/N = 3).