Morphological Evolution of Ag₂O Microstructures from Cubes to Octapods and Their Antibacterial Activities

Abstract

The selective synthesis of inorganic oxides with unique morphology has attracted considerable interest because of their morphology-dependent properties and applications. 1-3Efforts on most synthetic inorganic oxides have been focused on preparing a stable morphology rather than providing a strategy for producing various morphologies. Therefore, well-controlled methods for synthesizing inorganic oxides with a systematic evolution of morphology should be developed by adjusting the experimental conditions. Among the morphology-controlled syntheses of inorganic oxides, cuprous oxide (Cu 2 O) has been widely investigated due to its ease of preparation.4-8 The morphology-dependent photocatalytic and antibacterial properties of Cu 2 O were also studied recently.9-11 Although Cu 2 O and silver oxide (Ag 2 O) have similar cubic crystal structures, relatively little is known about the morphology-controlled synthesis and physical properties of Ag 2 O.12,13 To date, a study of the morphology-dependent antibacterial effect of Ag 2 O has reported only for different polyhedral shapes including octahedrons, truncated octahedrons, and cubes.14 This study provided a simple precipitation method for the morphological evolution of Ag 2 O from cubes to octapods. Furthermore, the morphology-dependent antibacterial activity of Ag 2 O against E. coli was also examined.Ag 2 O products with various morphologies were prepared from a silver-pyridine (Py) complex solution. Figure 1 shows the X-ray diffraction (XRD) patterns of Ag 2 O prepared using different amounts of AgNO 3 with 1.0/ 40/10 molar ratios of AgNO 3 /pyridine/NaOH, respectively. All peaks corresponded to those reported for bulk Ag 2 O (JCPDS 12-0793, a = 0.4736 nm) with a cubic structure and impurities. Figure 2 shows scanning electron microscopy (SEM) images of Ag 2 O prepared with different amounts of AgNO 3 . At 2.5 mL of AgNO 3 , Ag 2 O formed a regular cubic shape, as shown in Figure 2(a). The mean length of each side was 600 nm. At 5.0 mL of AgNO 3 , Ag 2 O formed a cubic shape, and the mean length of each side was 700 nm. Void spaces were created at the center of the cubic crystal planes, as shown in Figure 2 (b). When the amount of AgNO 3 was increased to 7.5 mL, the void spaces at the center of the cubic crystal planes increased further, as shown in Figure 2(c). As the amount of AgNO 3 was increased up to 20 mL, octapods with eight identical Ag 2 O horns were formed (Figure 2(d)).

The Potential Impact of Biofield Energy Treatment on the Physical and Thermal Properties of Silver Oxide Powder

“…It can be observed that the control sample showed the crystalline peaks at Bragg angle (2θ) 32.72°, 37.95°, 54.78°, 65.28° and 68.6° which were attributed to the crystalline planes (111), (200), (220), (311), and (222) according to Joint committee on powder diffraction standards (JCPDS) file no. 12-0793 [18]. The treated sample also exhibited the similar peaks at Bragg angle 32.72º, 37.97º, 54.78º, 65.31º, and 68.59º.…”

Facet Effect of Ag3PO4 Crystals on Antibacterial Activities

“…The final solution was stirred for 20 min and incubated for 4 h at room temperature. The synthesis of cubic Ag 2 O has been reported previously . In a typical synthesis of cubic Ag 2 O, a mixed solution of water (994.2 mL), 0.1 M AgNO 3 aqueous solution (2.5 mL), and pyridine (0.848 mL) was prepared, and then a 1.0 M NaOH aqueous solution (2.5 mL) was quickly added to the mixed solution.…”

Synthesis, Morphological Control, and Properties of Silver Nanoparticles in Potential Applications

“…Different Ag 2 O morphologies containing cubic structures were prepared based on an Ag–pyridine complex solution, where pyridine acts as the ligand for Ag + ions. Ag 2 O was obtained by the reaction of Ag–pyridine complex in the base media (Figure H) . Several reports concerning the fabrication of Ag cubic structures have been published (Figure I) …”