Determination of Hydrogen Peroxide by Cyclic Voltammetry Based on Nano TiO₂ and TiN as Working Electrode

A method for determination of H₂O₂ by cyclic voltammetry using nano TiO₂ and TiN materials as working electrode was established. The lower surface of Ti sheet was polished in polishing solution including 10.0 g of ammonium fluoride, 0.6 g of urea, 24 mL of 30% (mass fraction) hydrogen peroxide solution and 24 mL of nitric acid, and treated with ultrasonic for 15 min in a mixture of 15 mL of acetone, 15 mL of anhydrous ethanol and 15 mL of water. Then bright Ti sheet obtained was used as anode, and ordinary Ti sheet was used as cathode. TiO₂ rough film, TiO₂ nanotube and TiO₂ nanopore with different morphologies were prepared in different electrolytes1.0 mol·L^-1 sulfuric acid solution for TiO₂ rough film; a mixture of 50 mL of glycerin, 50 mL of water, 0.2 mol·L^-1 sulfuric acid solution and 0.5% (mass fraction) sodium fluoride solution for TiO₂ nanotube; a mixture of 100 mL of glycol, 1 mL of water and 0.38% (mass fraction) ammonium fluoride solution for TiO₂ nanopore by anodic oxidation method, and TiN rough film, TiN nanotube and TiN nanopore were obtained by ammonia thermal reduction reaction. TiO₂ and TiN materials were used as working electrode, platinum sheet as auxiliary electrode, and Ag/AgCl as reference electrode, and H₂O₂ was determined by cyclic voltammetry with three electrodes system in phosphate buffer solution (pH 7.0). It was showed that the rate constants of TiN rough film, TiN nanotube and TiN nanopore electrode were 2.39×10^-6, 3.03×10^-6cm·s^-1 and 6.40×10^-6 cm·s^-1, respectively. Using TiO₂ rough film, TiN rough film, TiO₂ nanotube, TiN nanotube, TiO₂ nanopore and TiN nanopore as working electrodes, linear relationships between concentrations of hydrogen peroxide and their reduction peak currents were kept in definite ranges, with detection limits (3s/k) of 23.30, 14.29, 19.9, 10.60, 16.90, 5.02 μmol·L^-1. 50 μmol·L^-1 H₂O₂ solution dropped in phosphate buffer solution (pH 7.0) was determined by chronoamperometry at -0.4 V of externaly applied voltage, and RSDs (n=5) of response currents of TiN rough film, TiN nanotube and TiN nanopore were 4.7%, 3.2% and 7.3%, respectively.