High-efficiency reduction of p-nitrophenol on green-synthesized gold nanoparticles decorated on ceria nanorods

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 CeO(2) 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 CeO(2) increased the specific surface area, pore diameter, and pore volume compared with pure CeO(2) (90 m(2) g(−1), 23.8 Å, and 0.110 cm(3) g(−1)versus 72 m(2) g(−1), 23.0 Å, and 0.089 cm(3) g(−1)). The splitting peaks of the surface oxygen and their shifting at lower temperatures compared with CeO(2) nanorods were found thanks to the Au–CeO(2) 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/NaBH(4) 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.