Synthesis of Diverse Ag2O Crystals and Their Facet-Dependent Photocatalytic Activity Examination

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• 作者：Ying-Jui Chen ; Yun-Wei Chiang ; Michael H. Huang
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：August 3, 2016
• 年：2016
• 卷：8
• 期：30
• 页码：19672-19679
• 全文大小：621K
• 年卷期：0
• ISSN：1944-8252

文摘

Sub- to micrometer-sized Ag₂O cubes, great rhombicuboctahedra, cuboctahedra, corner-truncated octahedra, octahedra, and rhombic dodecahedra have been synthesized at room temperature using simple molar ratios of NH₄NO₃, NaOH, and AgNO₃ solutions with a short reaction time. In addition, tuning the concentration of NH₃ in the solution can provide more particle morphologies including edge- and corner-truncated cubes, small rhombicuboctahedra, and edge-truncated octahedra to enrich Ag₂O shape diversity. X-ray photoelectron spectroscopy (XPS) spectra indicate surface composition of various crystals as pure Ag₂O. Diffuse reflectance spectra have been used to determine the band gap of Ag₂O cubes. Ag₂O cubes, octahedra, and rhombic dodecahedra having the same total particle surface area were used for facet-dependent photocatalytic activity comparison in the degradation of methyl orange. Cubes are comparably highly active for this reaction, while octahedra and rhombic dodecahedra give moderate and low catalytic activities, respectively. Electron paramagnetic resonance (EPR) measurements confirm this reactivity order. Although all Ag₂O samples show significant etching during photocatalysis, metallic silver is not produced.