Studies On The Electrochemistry Of SnO₂Modified Carbon Paste Electrode

The nano SnO2and nano gold particle with different size were prepared by gel-sol method. Two modified carbon paste electrodes, nano SnO2modified carbon paste electrode and SnO2modified with nano gold particle were obtained. Both of the modified electrodes were utilized to determine hydrogen peroxide and glucose, respectively.1.This paper developed a SnO2modified Carbon paste electrode as the detection of hydrogen peroxide (H2O2) sensor Hydrogen peroxide (H2O2) was determined by cyclic voltammetry and current-time curve method. Phosphate buffer solution pH, SnO2modified content and other factors, which may influence the determination of H2O2were study, respectively. Based on above, potentiometric determination of H2O2as achieved in pH was5.7, the quality proportion of SnO2and graphite was1:5. The resulting SnO2nanoparticles modified sensor showed a good sensitivity with a linear range of1×l0-5-2.19×l0-3mol/L (correlation coefficient R=0.9992) and its detection limit was2.5×10-6mol/L (S/N=3). The preparation process of the proposed sensor was convenient, and the sensor showed high sensitivity, low detection limit and good stability.2.Nanometer gold particle has the normal characteristics of nano-particle:size effect, surface effect, small size effect and so on. What is more, gold nano-particle, with good biocompatibility, can keep the biological activity of enzyme after the enzyme adsorbed on gold nano-particle. Nano SnO2has strong electric catalytic activity. Mingle the two kinds of the nano-particle with carbon paste to prepare modified carbon paste electrode, and then added the glucose oxidase on the electrode to construct the glucose electrochemical sensor. The main affecting factors, including dissolved oxygen, the size of gold nano-particle, the amount of gold and SnO2nano-particle, and the pH, were investigated by cyclic voltammetry and difference pulse voltammetry, respectively. The results show the best determination condition for glucose are:the content of SnO2was2%,6nm gold nano particle in5ml, and the buffer pH5.5. The obtained SnO2and gold nano-particle modified sensor showed a good sensitivity with a linear range of4×10-5-8×10-4mol/L (correlation coefficient R=0.997) and its detection limit was2x10-5mol/L (S/N=3). Adding Tin dioxide make the modified electrode has higher detection sensitivity to glucose.