Characteristics of N-doped titanium oxide and photodegradation of formaldehyde using visible light lamp and light emitting diode
Sustain. Environ. Res., 22(2), 69-76 (2012)
Je-Lueng Shie, Ching-Yuan Chang, Chyow-San Chiou, Yi-Hung Chen, Chia-Hsiang Lee and Chia-Chi Chang
Formaldehyde, N-doped oxide photocatalyst, light emitting diode, indoor pollution,
This study investigates the surface modification of N-doped TiO2 and the photodecomposition of formaldehyde from indoor pollution sources using a visible light lamp and a light emitting diode(LED). An X-ray single crystal diffractometer, scanning electron microscope, ultraviolet/visible spectroscopy and BET are used to measure the surface characteristics of the N-doped TiO2. The operation parameters which affect the formaldehyde decomposition in the photodecomposition reaction are also examined. The parameters include different light sources, fabrication methods of N-doped TiO2 and the mass of the photocatalysts. The results show that the TiNH400 prepared by Ti(SO4)2 and ammonia liquor calcined at 400 °C (673 K) has the finest size of about 30-40 nm and the largest surface area (99 m2 g-1) of the modified TiO2 examined in this study. The TiNH400 has a red shift absorption spectra of about 400-440 nm in the lower energy region, which reveals its ability to adsorb the visible light and near UV light. Light sources of blue LED (BLED), white LED (WLED) and green LED are tested for the photodecomposition of formaldehyde. The results show that the decomposition efficiency of formaldehyde increases with the higher light energy and shorter wavelength of the light sources. The energy effectiveness of the BLED and WLED is about 40 times higher than that of traditional lamps. Therefore, in applying this technology to indoor air pollutant cleaners, a potentially high market value for them can be anticipated in the near future.