Fe3O4/g-C3N4/TiO2 catalyst has been fabricated using a simple ultrasonic method with high photocatalytic activity. The morphology, structure and optical properties of Fe3O4/ g-C3N4/TiO2 were systematically investigated by a variety of characterization techniques. The optimum degradation conditions were investigated by degrading tetracycline (TC) under visible light irradiation. The results showed that the degradation efficiency was the highest when the initial TC concentration was 5.0 mg/L, the pH value was 11 and the catalyst dosage was 1.0 g/L. After 100 min of visible light irradiation, the degradation efficiency of TC achieved at 73.61%, which was 1.64 and 1.19 times that of g-C3N4 and Fe3O4/ g-C3N4, respectively. Moreover, Fe3O4/ g-C3N4/TiO2 had good stability and recyclability. The results of capture experiments showed that ‧O2 − and ‧OH were the main active species during the photocatalytic process, and a possible photocatalytic reaction mechanism of Fe3O4/ g-C3N4/TiO2 catalyst was proposed. This study provides a new way to improve the photocatalytic performance of g-C3N4, which has great potential in degrading pollutants such as antibiotics in wastewater.

N-doped Na2Ti6O13@TiO2 (denoted as N-NTO@TiO2) composites are successfully synthesized using a simple two-step process: 1) ball-milling of TiO2 with Na2CO3 followed by heat treatment at 900oC; 2) mixing of the prepared Na2Ti6O13 with titanium isopropoxide and calcining with urea at 500oC. The prepared composites are characterized using XRD, SEM, TEM, FTIR, and BET. The N-NTO@TiO2 composites exhibit well-defined crystalline and anatase TiO2 with exposed {101} facets on the external surface. Moreover, dopant N atoms are uniformly distributed over a relatively large area in the lattice of the composites. Under visible light irradiation, ~51% of the aqueous methylene blue is photodegraded by N-NTO@TiO2 composites, which is higher than the values shown by other samples because of the coupling effects of the hybridization of NTO and TiO2, N-doping, and presence of anatase TiO2 with exposed {101} facets.

Nitrogen-doped titanium dioxide (N-doped TiO2) is attracting continuously increasing attention as a material for environmental photocatalysis. The N-atoms can occupy both interstitial and substitutional positions in the solid, with some evidence of a preference for interstitial sites. In this study, N-doped TiO2 is prepared by the sol–gel method using NH4OH and NH4Cl as N ion doping agents, and the physical and photocatalytic properties with changes in the synthesis temperature and amount of agent are analyzed. The photocatalytic activities of the N-doped TiO2 samples are evaluated based on the decomposition of methylene blue (MB) under visible-light irradiation. The addition of 5 wt% NH4Cl produces the best physical properties. As per the UV-vis analysis results, the N-doped TiO2 exhibits a higher visible-light activity than the undoped TiO2. The wavelength of the N-doped TiO2 shifts to the visible-light region up to 412 nm. In addition, this sample shows MB removal of approximately 81%, with the whiteness increasing to +97 when the synthesis temperature is 600℃. The coloration and phase structure of the N-doped TiO2 are characterized in detail using UV-vis, CIE Lab color parameter measurements, and powder X-ray diffraction (XRD).

TiO2 nanowires were grown by thermal oxidation of TiO powder in an oxygen and nitrogen gas environment at 1000 oC. The ratio of O2 to N2 in an ambient gas was changed to investigate the effect of the gas ratio on the growth of TiO2 nanowires. The oxidation process was carried out at different O2/N2 ratios of 0/100, 25/75, 50/50 and 100/0. No nanowires were formed at O2/N2 ratios of less than 25/75. When the O2/N2 ratio was 50/50, nanowires started to form. As the gas ratio increased to 100/0, the diameter and length of the nanowires increased. The X-ray diffraction pattern showed that the nanowires were TiO2 with a rutile crystallographic structure. In the XRD pattern, no peaks from the anatase and brookite structures of TiO2 were observed. The diameter of the nanowires decreased along the growth direction, and no catalytic particles were detected at the tips of the nanowires which suggests that the nanowires were grown with a vapor-solid growth mechanism.

가시광선에 감응하는 광촉매를 제조하기 위하여 TiO2에 질소(N)를 도핑하여 N-TiO2를 제조하였다. 제조한 광촉매의 결정성, 입자 형상 및 도핑 상태는 XRD, FE-SEM 및 XPS를 이용하여 조사하였다. 제조한 광촉매의 활성 평가는 메틸렌블루의 광분해로 조사하였다. 제조한 광촉매는 anatase type이었으며, pH가 높을수록 결정화도가 향상되었다. 제조한 광촉매의 입자 크기는 pH 2.0에서 5.42 nm, pH 4.7에서 5.99 nm, pH 9.0에서 7.58 nm로, 입자 크기는 pH가 증가 할수록 약간씩 증가하였다. 광촉매의 활성은 결정화도에 비례하였다. TiO2에 N를 도핑하여 제조한 N-TiO2가 가시광선 하에서도 활성을 나타냈다. TiO2에 도핑한 N는 격자 속에 존재하는 것이 아니라 표면에 존재하였다.

This study evaluated the photocatalytic oxidation efficiency of volatile organic compounds by Cu2O -TiO2 under visible-light irradiation. Cu2O-TiO2 was synthesized by an ultrasonic-assisted method. The XRD result indicated successful p-n type photocatalysts. However, no diffraction peaks belonging to TiO2 were observed for the Cu2O-TiO2. The Uv-vis spectra result revealed that the synthesized Cu2O-TiO2 can be activated under visible-light irradiation. The FE-TEM/EDS result showed the formation of synthesized nanocomposites in the commercial P25 TiO2, the undoped TiO2, and Cu2O-TiO2 and componential analysis in the undoped TiO2 and Cu2O-TiO2. The photocatalytic oxidation efficiencies of benzene, toluene, ethylbenzene, and o-xylene with Cu2O-TiO2 were higher than those of P25 TiO2 and undoped TiO2. These results indicate that the prepared Cu2O-TiO2 photocatalyst can be applied effectively to control gaseous BTEX.

In this study, N doped TiO2 (TiO-N) thin film was prepared by DC magnetron sputtering method to show the photocatalytic activity in a visible range. Various gases (Ar, O2 and N2) were used and Ti target was impressed by 1.2 kW-5.8 kW power range. The hysteresis of TiO-N thin film as a function of discharge voltage wasn't observed in 1.2 and 2.9kW of applied power. Cross sections and surfaces of thin films by FE-SEM were tiny and dense particle sizes of both films with normal cylindrical structures. XRD pattern of TiO2 and TiO-N thin films was appeared by only anatase peak. Red shift in UV-Vis adsorption spectra was investigated TiO-N thin film. Photoactivity was evaluated by removal rate measurement of suncion yellow among reactive dyes. The photodegradation rate of TiO2 thin film on visible radiation was shown little efficiency but TiO-N was about 18%.

The aim of this study is, firstly, to find out what kinds of inorganic species are produced in the photocatalytic oxidation of ammonium-nitrogen containing water and, secondly, to seek the influence of anion for the photocatalytic oxidation of ammonium contained compounds. The photoenergy above 3 eV(λ＜415 nm) was effectively absorbed by TiO2 and TiO2/polymer was used to be oxidized NH4-N in wastewater to NO3-N. Existing the anion as Cl-, the rate of photocatalytic oxidation decreased regardless of other condition. This result showed that the chloride ions reduced the rate of oxidation by scavenging oxidizing radical species as OH- and OCl-. Some of the added ion might have blocked the active sites of the catalyst surface, thus deactivated the catalyst.