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In this study, C-N-S-tridoped TiO 2 composite was fabricated from TiO 2 prepared from ilmenite ore and thiourea by means of hydrothermal method. The obtained material was characterized by X-ray diffraction, Raman scattering spectroscopy, UV-Vis diffuse reflectance spectroscopy, nitrogen adsorption-desorption isotherms, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). It was found that C-N-S-tridoped TiO 2 material has a large specific surface area, showing good photocatalytic activity on the degradation of antibiotic tetracycline in visible light region. The study on the mechanism of tetracycline photodegradation using the liquid chromatography with mass spectrometry was performed. It was found that tetracycline has been degraded over C-N-S-tridoped TiO 2 catalyst into many different intermediates which can eventually be converted into CO 2 and H 2 O. The kinetics of photocatalytic decomposition of tetracycline were investigated. In addition, the obtained material could catalyze well the degradation of other antibiotics (ciprofloxacin and chloramphenicol) and dyes (rhodamine-B, methylene blue, and organe red). The catalyst was stable after five recycles with slight loss of catalytic activity, which indicates great potential for practical application of C-N-S-tridoped TiO 2 catalyst in treatment of wastewater containing tetracycline in particular or antibiotics in general.

In this work, quantum dots sensitized solar cells had been successfully prepared based on Cu 2 S counter electrode and TiO 2 /CdS/Cd 1−x Mn x Se/ZnS photoanode. The highest power conversion efficiency was 3.77%. Herein, we studied the degradation process of quantum dots sensitized solar cells by investigating the photocurrent-voltage (I-V) curves and electrochemical impedance spectroscopy. The results showed that there was a downward trend of the power conversion efficiency from 3.77% to 1.52%. This trend was proved by the increase of dynamic resistance, including: charge recombination resistance at counter electrode/electrolyte and FTO/TiO 2 interface ( R ct1 increased from 204.5 Ω to 780.1 Ω), charge transfer resistance within the TiO 2 film and at the TiO 2 /QDs/electrolyte interface ( R ct2 increased from 24.65 Ω to 466.7 Ω). The decreased efficiency and increased dynamic resistance might cause the quantum dots sensitized solar cell degradation.

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