Photoelectrochemical Activity Of Nickel Doped TiO₂Film For Photoelectrocatalytic Degradation Of Selected Antibiotics

The nickel doped TiO₂thin films （dopant amount varying from0.1wt.%to0.9%wt.%） were fabricated on different substrates including indiumtin oxide （ITO） andtitanium via liquid phase deposition technique. The surface morphology, structure andphotoelectrchemical properties of the resultant films were characterized bychronoamperometry（CA）、 electrochemical impedance spectroscopy （EIS）、Mott-schottky（MS） measurement、field emission scanning electron microscopy （FESEM）、X-ray diffraction （XRD）and other modern phisical chemical methods，and investigate theinfluence of different doping methods on thin films. The results indicate that theas-prepared Ni-TiO₂films show excellent adherence to the substrate and good surfacequality. The as-prepared TiO₂films are mainly anatase phase. Ni modifcation couldgreatly enhance electrocatalytic and photoelectrocatalysis activity of TiO₂thin films, andTiO₂films on the Ti substrate havea higher activity for photoelectric chemical responsethan that on indiumtin oxide. And compared with Ni secondly doped TiO₂thin flmselectrode, the Ni doped TiO₂thin flms electrode infuences the photoelectrocatalysisactivity greatly. The optimum doping concentration is0.7wt.%.In the second and third part of paper, the photoelectrocatalytic （PEC） properties of0.7wt.%Ni-TiO₂films were delibrated through the photoelectrodegradation ofsulfamethoxazole （SMZ） and ciprofloxacin （CF）. It is declared that the PEC efficiency ishigher than the sum of photocatalytic and electrochemical efficiency, which has asynergetic effect. The photoelectrocatalytic degradation process is proved to abide by thefirst-order reaction kinetics. The main factors influencing the the PEC degradation processof SMZ and CF such as initial concentration of the two pollutants, applied bias potential,pH value, supporting electrolyte concentration and dissolved oxygen were optimized. Inthe most optimum conditions, more than75%of two pollutants degradation and55%ofCOD reduction was achieved within60-min PEC treatment. In addition, the mechanism ofthe two pollutants photodegradation was preliminarily investigated in the paper: firstly,with together effect of hydroxyl radicals （OH） and UV irradiation, hydroxylation of theprimary intermediate products is produced. The benzene ring and the isoxazole ring ofsulfamethoxazole and the piperazine ring and the benzene ring of ciprofloxacin cleavage, aromatic hydrocarbons intermediates are generated. As the reaction proceeded, thoseintermediates are degraded to some of small molecular acid by the action of OH andfinally mineralized to CO₂、H₂O、NH⁴⁺and NO₃^-etc.