Papers by Keyword: Au Catalyst

Abstract: A novel and well-organized study for the synthesis and enhanced catalytic activity of Au/TiO₂ catalysts has been developed. A momentous improvement in the catalytic activity of Au/TiO₂ in CO oxidation and preferential oxidation reaction by thermal treatment has been studied. Au/TiO₂ catalyst (Au (1 wt.%) supported on TiO₂) was prepared by conventional deposition-precipitation method with NaOH followed by washing, drying and calcination in air at 400 °C for 4 h. Thermal treatment of Au/TiO₂ was performed at 450 °C under 0.05 mTorr. The activity of the catalysts has been examined in the reaction of CO oxidation and preferential oxidation (PROX) at 25-250 °C. The catalytic performance was found to be strongly affected by thermal treatment of the prepared catalyst prior to the reaction. Heat treatment after Au deposition has a positive effect on the CO oxidation performance. This is attributed to the introduction of a stronger interaction between the oxide and Au which improves the catalytic activity.

Abstract: We have studied the Au+Ga alloy seeding method. Single-crystal GaN nano-column arrays were grown using metalorganic chemical vapor deposition (MOCVD) and their properties were investigated as a function of the growth parameters and Au thin film thickness. Au-coated Si(111) substrates were used for the growth of GaN nano-columns. The diameter and length of as-grown nano-column ranged from 100 to 500 nm and 1 to 5 μm, respectively. The morphology of the columns was investigated using scanning electron microscopy. Energy dispersive X-ray spectroscopy and photoluminescence were used for evaluating of its qualitative analysis and to evaluate the optical properties, respectively. Two important growth parameters were considered, the thickness of the Au thin film and the gallium flow rate. The density and tendency of the nano-columns depend on each of these growth parameters. It is believed that the catalytic activity of gold is determined by the size of the Au+Ga solid solution particles, and smaller Au+Ga clusters showed significant reactivity in the growth of one-dimensional GaN nano structures.