Iridium Oxide Nanoparticles and Iridium/Iridium Oxide Nanocomposites: Photochemical Fabrication and Application in Catalytic Reduction of 4-Nitrophenol

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• 作者：Di Xu ; Peng Diao ; Tao Jin ; Qingyong Wu ; Xiaofang Liu ; Xin Guo ; Hongyu Gong ; Fan Li ; Min Xiang ; Yu Ronghai
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：August 5, 2015
• 年：2015
• 卷：7
• 期：30
• 页码：16738-16749
• 全文大小：837K
• ISSN：1944-8252

文摘

Hydrous iridium oxide (IrO_x) nanoparticles (NPs) with an average diameter of 1.7 卤 0.3 nm were prepared via photochemical hydrolysis of iridium chloride in alkaline medium at room temperature. The photoinduced hydrolysis was monitored by time-dependent ultraviolet鈥搗isible (UV鈥搗is) spectroscopy, and the effects of the incident wavelength and irradiation time on the production of IrO_x NPs were systematically investigated. It was found that UV鈥搗is irradiation is crucial for the generation of IrO_x NPs during the hydrolysis of IrCl₃, and once the irradiation was turned off, the hydrolysis reaction stopped immediately. The production rate of IrO_x NPs greatly depended on the incident wavelength. There is a critical wavelength of 500 nm for the hydrolysis reaction, and IrO_x NPs can only be produced under the illumination with an incident wavelength shorter than 500 nm. Moreover, the shorter the incident wavelength, the faster the growth rate of IrO_x NPs. The obtained IrO_x NPs were highly stable during two months of storage at 4 掳C. The Ir/IrO_x nanocomposites were prepared by surface reduction of IrO_x NPs with NaBH₄. The microstructure of the Ir/IrO_x composite was characterized by transmission electron microscopy (TEM), and the presence of zero-valence Ir was confirmed by the X-ray diffraction (XRD) result. The Ir/IrO_x nanocomposite exhibited good catalytic activity and high recycling stability toward the reduction of 4-nitrophenol. The catalytic activity per unit surface area of the Ir/IrO_x composite catalyst was increased by a factor of 15 compared to that of pure Ir catalyst. The presence of the Ir/IrO_x interfaces in the composite catalyst is believed to be responsible for the high activity.