Highly efficient catalytic reductive degradation of various organic dyes by Au/CeO2-TiO2 nano-hybrid

Abstract

Highly improved catalytic reductive degradation of different organic dyes, in the presence of excess NaBH<inf>4</inf> over Au/CeO<inf>2</inf>-TiO<inf>2</inf> nano-hybrid as the catalyst is reported in this study. CeO<inf>2</inf>-TiO<inf>2</inf> nanocomposite was prepared by a facile co-precipitation method using ultra-high dilute aqueous solutions. Small amount of Au (only 1 wt%) was loaded onto the nanocomposite material by deposition-precipitation with urea (DPU) method to fabricate the ternary Au/CeO<inf>2</inf>-TiO<inf>2</inf> nano-hybrid. The catalysts were characterized by the representative techniques like XRD, BET surface area, ICP-AES, UV-Vis diffuse reflectance spectroscopy, TEM and XPS. The Au/CeO<inf>2</inf>-TiO<inf>2</inf> nano-hybrid along with NaBH<inf>4</inf> exhibited remarkable catalytic activities towards all the probed dyes, namely Methylene Blue, Methyl Orange, Congo Red, Rhodamine B and Malachite Green, with a degradation efficiency of ?100% in a short reaction time. The degradation reaction followed pseudo-first-order kinetics with respect to the concentration of the dye. Different parameters that affect the rate of the reaction are discussed. A plausible mechanism for methylene blue degradation has also been proposed. [Figure not available: see fulltext.] © 2017, Indian Academy of Sciences.