Degradation of 4-chlorophenol and NO x Using Ultrasonically Synthesized TiO2 Loaded Graphene Oxide Photocatalysts

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-CP 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-CP. A combined method of ultrasound and photocatalysis was also investigated for the effective degradation of 4-CP. High frequency (215 kHz) ultrasound exhibited higher degradation of 4-CP 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 NO x 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 NO x 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.