Formation of AgI/TiO2 nanocomposite leads to excellent thermochromic reversibility and photostability

Abstract

AgI/TiO 2 nanocomposite was prepared and characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and diffusive reflectance UV-vis (DRUV-vis) absorption spectra at different temperatures. The AgI/TiO 2 nanocomposite exhibits thermochromic switching phenomena at the phase b-a transition temperature of AgI with the evolution of its color from light yellow at ambient temperature to dark khaki at 150 C. It was found for the first time that the formation of the AgI/TiO 2 nanocomposite not only results in a considerable reduction of thermochromic transition temperature of AgI as well as excellent thermochromic reversibility, but also leads to excellent photostability under illumination with an indoor fluorescent lamp. Based on the characterization results by photoluminescence, transient photocurrent decay and positron annihilation spectra, it is concluded that large surface defects, such as I À vacancy clusters (e.g. Ag + -I À V -Ag + -I À V -Ag + ) on the surface of AgI as deep electron traps, are responsible for the photodecomposition of pure AgI. The excellent photostability of the AgI/TiO 2 nanocomposite is due to the following reason: the surface I À vacancy clusters as deep electron traps in pure AgI are replaced by Ag + -O 2À -Ti 4+ bonds on the interface of AgI/TiO 2 , thus Ag n cluster formation through the surface migration of photogenerated Ag atoms is completely inhibited, resulting in the inhibition of photodecomposition of AgI.

Shape-dependent interplay between oxygen vacancies and Ag–CeO2 interaction in Ag/CeO2 catalysts and their influence on the catalytic activity

“…This feature can be reasonably assigned to the surface plasmon resonance (SPR) peak of Ag nanoparticles supported on CeO 2 . The SPR peak of Ag nanoparticles red-shifts with their particle size [ 44,45]; therefore, the average size of Ag nanoparticles in Ag/CeO 2 samples follows the order: 3%-Ag/c-CeO 2 > 1%-Ag/c-CeO 2 % 3%-Ag/ r-CeO 2 .…”

Fabrication of a PdAg mesocrystal catalyst for the partial hydrogenation of acetylene

“…tion of orthopositronium atoms formed in large pores [60], s 2 is due to positrons trapped by large size defects [62] located on the surface or subsurface of a sample [63], while the shortest lifetime component (s 1 ) generally arises from the annihilation of free positrons in the bulk section of a material [64]. Thus the relative intensities (I) of s 1 , s 2 , and s 3 provide information about the relative concentration of different defects [65,66].…”

AgI/TiO2 nanobelts monolithic catalyst with enhanced visible light photocatalytic activity

“…Under ambient condition, it exists in two distinct phases, hexagonal β-AgI and zinc-blende γ-AgI. It has been reported that the presence of a support (e.g.TiO 2 , Al 2 O 3 , SiO 2 ) could stabilize AgI NPs by inhibiting the photographic process [15,19,20]. For example, Hu and co-workers prepared P25-supported AgI by a deposition precipitation route, which exhibited highly efficient and stable photocatalytic activity in destroying bacteria and decomposing K-2G dye [21].…”