摘要
Sub- to micrometer-sized Ag 2 O cubes, great rhombicuboctahedra, cuboctahedra, corner-truncated octahedra, octahedra, and rhombic dodecahedra have been synthesized at room temperature using simple molar ratios of NH 4 NO 3 , NaOH, and AgNO 3 solutions with a short reaction time. In addition, tuning the concentration of NH 3 in the solution can provide more particle morphologies including edge- and corner-truncated cubes, small rhombicuboctahedra, and edge-truncated octahedra to enrich Ag 2 O shape diversity. X-ray photoelectron spectroscopy (XPS) spectra indicate surface composition of various crystals as pure Ag 2 O. Diffuse reflectance spectra have been used to determine the band gap of Ag 2 O cubes. Ag 2 O 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 Ag 2 O samples show significant etching during photocatalysis, metallic silver is not produced.