RESUMO
A green synthesis using extract from Citrus maxima peel was developed to fabricate Au-Ce catalysts for the reduction of p-nitrophenol (PNP). Au nanoparticles with a diameter of 6.6 ± 2.5 nm were deposited onto the surface of CeO2 nanorods with a length of 33.1 ± 15.0 nm and a diameter of 7.1 ± 2.1 nm. The mesoporous and non-porous capillary structures of these materials were observed. The interaction between Au and CeO2 increased the specific surface area, pore diameter, and pore volume compared with pure CeO2 (90 m2 g-1, 23.8 Å, and 0.110 cm3 g-1 versus 72 m2 g-1, 23.0 Å, and 0.089 cm3 g-1). The splitting peaks of the surface oxygen and their shifting at lower temperatures compared with CeO2 nanorods were found thanks to the Au-CeO2 interaction, suggesting that their reduction occurred more easily. The synthesized Au-Ce catalysts exhibited excellent activity in the reduction of PNP to p-aminophenol. The 0.2Au-Ce catalyst was the most efficient one for PNP reduction, enabling the conversion of PNP in 30 minutes with a catalyst concentration of 20 mg L-1 and a PNP/NaBH4 molar ratio of 1/200. Moreover, the 0.2Au-Ce catalyst could be reused for at least five consecutive cycles without considerable loss of its activity.
