Catalytic reduction of p-nitrophenol on Au/TiO2 powder and Au/TiO2 membrane.

The current work reports on the development of Au nanoparticles (NPs) supported on titania membrane towards enhancing catalytic reduction of p-nitrophenol. Titania membrane was successfully fabricated via chemical anodization method at 50 V in ethylene glycol: water as the electrolyte. A well-ordered nanotubular array of 138±18 nm pore diameter was observed by electron microscope. The Au NPs were deposited on titania in form of membrane (Au/TiO₂ MF) by immersing in Au precursor (HAuCl₄) solution at pH 7 for 2 hours. Meanwhile, the preparation of Au/TiO₂ powder form (PF) follows similar procedures but using commercial TiO₂ (Degussa P25). The FTIR result shows the shifting of peak at 1067 cm^-1 to 1107 cm⁻¹ for TiO₂ membrane and Au/TiO₂ MF, respectively which corresponds to Ti-O bond. Meanwhile the Ti-O bond was shifted from 1066 cm^-1 (titania powder) to 1097 cm^-1 for Au/TiO₂ PF. The shifting of IR peak indicates successful attachment of Au on titania. Surface morphology by FESEM shows the Au of 27.95±5.8 nm and 30.59±2.11 nm size was obtained for Au/TiO₂ in MF and PF, respectively. The Au/TiO₂ MF exhibits superior catalytic activity in the reduction of p-nitrophenol, with a rate constant (k) value of 5.9 x 10-3 s⁻¹. A slight decreased in the k value was observed after this catalyst been reused. This study offers an effective development of catalytic membrane with high activity and good stability. [ABSTRACT FROM AUTHOR]