Preparation And Application Of Electrochemical Sensors Based On CoNi Precursor Nano/Micro Self-Assembled Nano Composite

ObjectiveCobalt and Nickel have rich electrochemical properties.Take advantage of the two transition metal elements to prepare Co Ni precursor nanomaterials and Ni complex precursor nanomaterials without annealing and calcination.Various characterization methods were used to reveal the morphology,crystal form,and chemical structure speculation of the Co Ni precursor nanomaterials.Finally,quantitative detection of dopamine or ascorbic acid was performed on the modified electrode by cyclic voltammetry method,differential pulse voltammetry method,chronoamperometry method,etc.MethodsCoNi and Ni complex precursor nanomaterials were prepared by homogeneous precipitation with urea as the precipitant.Scanning electron microscope,Transmission electron microscope,X-ray diffraction,Dispersion spectrum,X-ray photoelectron spectroscopy,Fourier transform infrared absorption,Comprehensive thermal analysis,and BET specific surface area test were used to characterize the Co Ni precursor composite.The modified electrode was obtained by drip coating glassy carbon electrodes,and the printed electrode was obtained by a mechanical printing technique.Finally,electrochemical characterization was test by cyclic voltammetry,differential pulse voltammetry,and chronoamperometry.Result and ConclusionUsing urea as a precipitant,cobalt nitrate and nickel nitrate were homogeneously precipitated to obtain Co Ni precursor nano powder.Scanning electron microscopy and transmission electron microscopy showed that the morphology of the Co Ni precursor looks like sea urchin.X-ray diffraction,Dispersion spectroscopy,X-ray photoelectron spectroscopy,and Fourier transform infrared absorption speculate that the Co Ni precursor complex is a cobalt and nickel carbonate.The 5%Nafion and Co Ni precursor carbonate nano powder were co-modified on the GCE by the drop coating method.The cyclic voltammetry and differential pulse voltammetry were used to study the electrochemical behavior of dopamine and ascorbic acid on the electrode.The results showed that dopamine and ascorbic acid had a good response in 0.1 mol/L phosphate buffer solution.In the range of 0.1-10?mol/L,there is a good linear relationship which is r=0.9991 between dopamine peak current and concentration.The detection limit is0.0178?mol/L.In the range of 0.1-10 mmol/L,there is a good linear relationship which is r=0.9990 between ascorbic acid peak current and concentration.The detection limit is0.0272 mmol/L.The modified electrode can effectively avoid the interference of uric acid,ascorbic acid and glucose.The modified electrode has good repeatability and reproducibility.CoNi precursor electrodes,Ag/Ag Cl and carbon electrodes were printed on a polyester resin substrate by a screen printer to obtain Co Ni screen-printed electrodes.The cyclic voltammetry and differential pulse voltammetry were used to study the electrochemical behavior of dopamine and ascorbic acid on Co Ni screen-printed electrodes.Results showed that dopamine and ascorbic acid had a good response in 0.1 mol/L phosphate buffer solution.In the range of 1-35?mol/L,there is a good linear relationship which is r=0.9949 between dopamine peak current and concentration.In the range of 1-30mmol/L,there is a good linear relationship which is r=0.9877 between ascorbic acid peak current and concentration.The modified electrode can effectively avoid the interference of uric acid,ascorbic acid and glucose.The modified electrode has good repeatability and reproducibility.Ni complex precursor nano powder developed for detect dopamine with high sensitivity.Electrochemical experiments show that Ni complex/GCE modified electrode has high electrochemical activity for dopamine.In the range of 0.1-2.0?mol/L,the dopamine concentration and oxidation peak current show a linear equation relationship.The relationship is:I_{oxidation peak}=8.89 C_dopamine+2.81,r=0.9976,and the detection limit is0.0292?mol/L.In addition,the anti-interference test and stability test show that Ni complex/GCE modified electrode has reliable stability and excellent repeatability.