From β-Phase Particle to α-Phase Hexagonal-Platelet Superstructure over AgGaO₂: Phase Transformation, Formation Mechanism of Morphology, and Photocatalytic Properties

Abstract

We studied an orthorhombic-to-rhombohedral transformation of AgGaO 2 , which was performed in water at low temperature and accompanied by morphology variation, by using powder X-ray diffraction, UV-visible absorption spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy, and photocatalytic 2-propanol oxidization. The experimental results revealed that the crystal growth of the β-phase (orthorhombic AgGaO 2 ) to R-phase (rhombohedral AgGaO 2 ) in water could be divided into phase-transformation, transition, and mature periods. The effects of water and temperature on the phase transformation and crystal-structure correction were clarified. It is found that the morphology of the R-phase sample is a superstructure, the shape of which is influenced by the phase-transformation temperature. The morphology variation of β-phase particle to R-phase hexagonal platelet is a solid-liquid-solid growth process via the time-line based SEM images. The formation mechanism of this superstructure may be attributed to the growing-space competition.

Insight into the Humidity Dependent Pseudo-n-Type Response of p-CuScO2 toward Ammonia

“…SEM images of the CuScO 2 sample shown in Figure b show a “gypsum flower” morphology which is aggregated by thin hexagonal plates with a thickness of a few tens of nanometers. A similar morphology is also observed in the hydrothermally grown CuGaO 2 and aqueous synthesis of AgGaO 2 at 50 °C. , The TEM image (Figure c) of the isolated nanoplates shows a clear hexagonal structure, and the selected-area diffraction pattern indicates that the nanoplates are single crystals. The measured interplanar spacings are 0.278, 0.270, and 0.250 nm, corresponding to the distance of (101), (1), and (013) crystal planes of the 3R-CuScO 2 phase, respectively.…”

The Development of Better Photocatalysts through Composition‐ and Structure‐Engineering

“…Since Zou et al proposed In 1Àx Ni x TaO 4 as a multi-metaloxide photocatalyst with a high water-splitting capability to produce H 2 and O 2 in stoichiometric amounts under visiblelight irradiation, [17] a large amount of research has been done towards developing new multi-metal-oxide photocatalysts. [18][19][20][21] Ye and co-workers have developed a series of perovskite-type solid-solution photocatalysts, (Ag 1Àx Sr x )-A C H T U N G T R E N N U N G (Nb 1Àx Ti x )O 3 , that crystallized in orthorhombic (0 < x < 0.9) or cubic systems (0.9 < x < 1). As shown in Figure 4, the valence band (VB) and conduction band (CB) of (Ag 0.75 Sr 0.25 )(Nb 0.75 Ti 0.25 )O 3 are formed by the hybridized (Ag 4d +O 2p ) orbitals and the hybridized (Ti 3d +Nb 4d ) orbitals, respectively.…”

Controlled syntheses of cubic and hexagonal ZnIn2S4 nanostructures with different visible-light photocatalytic performance

“…Polymorphism of inorganic materials has attracted extensive interest since different polymorphs usually exhibit different properties. [1][2][3][4][5][6][7][8] The controlling of the occurrence of a specific polymorph in the preparation of inorganic materials is of fundamental importance, yet remains a long-standing challenge. ZnIn 2 S 4 is a ternary chalcogenide which belongs to the family of ternary compounds AB 2 X 4 .…”