▎ 摘　　要

TiO2, GO-TiO2, Pt-GO-TiO2 were synthesized using an ultrasound-assisted technique. The synthesized photocatalysts were characterized using XRD, UV-Vis, FTIR and TEM-EDX instruments. The photocatalytic activities of these catalysts were compared using the degradation of 4-chlorophenol (4-CP) in aqueous solutions. Pt-GO-TiO2 showed higher rate of degradation of 4-CP than that of bare TiO2. Doping of TiO2 with Pt (0.4 wt%) exhibited total degradation of 4-CP in 1 h under light irradiation. A similar trend was observed with mineralization of 4-OP using different catalysts which was monitored by total organic carbon (TOC) analysis. Among different solution pH, pH 6 showed high efficiency for the degradation of 4-OP. A combined method of ultrasound and photocatalysis was also investigated for the effective degradation of 4-OP. High frequency (215 kHz) ultrasound exhibited higher degradation of 4-OP than low frequency (20 kHz) of ultrasound. There was no synergistic effect of photocatalysis combined with ultrasound method but an additive effect was observed. Gas phase degradation of NOx was also carried out using the above catalysts and the results revealed that GO-TiO2 was an excellent catalyst for the total decomposition of toxic NOx gas in a short period of time without using Pt. GO was proved to be a useful support for photocatalysts effective for both gas phase as well as liquid phase reactions and, GO-TiO2 can be a viable catalyst for gas phase decomposition of air-pollutants.