Ga-Doped ZnO Nanostructured Powder for Cool-Nanopigment in Environment Applications

Abstract

Gallium (Ga) doped zinc oxide (ZnO) nanocrystals were successfully synthesized via a γ-radiation-assisted polymer-pyrolysis route. Ga doped ZnO samples with Ga and ZnO precursor salts with molar ratios of 0%, 3%, 5%, and 10% were produced. A γ-radiation dosage of 1.5 kGy was used for polymerization initiation during the sample preparation. The properties of the obtained nanocrystal samples were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR), UV-visible absorption, NIR-VIS-UV diffused reflectance, and high-resolution transmission electron microscopy (HR-TEM) characterization techniques. XRD results revealed the formation of ZnO nanocrystals with wurtzite structure for both Ga-doped and undoped ZnO samples. Noticeable increasing in the line broadening of the XRD peaks as well as pronounced decreasing of crystallite size were observed with the increasing Ga ratio in the samples. Optical peaks around Ga:ZnO samples showed a blueshift in the optical absorption peaks with increasing Ga content. These results are in good agreement with the dependency of crystallites size as well as grain size on Ga ratio obtained from XRD and TEM images, which make them fit well for the powder cool-pigment applications. The doped samples showed high values of NIR reflectance (RNIR*) with percentage varied from 84.25% to 89.05% that enabled them to qualify for cool-nanopigment applications. Furthermore, such doped samples registered low values of visible reflectance (RVIS*) that enabled to reduce the glare from the reflected visible sunlight.

Promising Cr-Doped ZnO Nanorods for Photocatalytic Degradation Facing Pollution

“…transition [14,[44][45][46][47]. Such a band is kept at the same energy position, which is in good agreement with the weak change of the band gap energy Eg with Cr doping as was reported in our previous work [11].…”

“…A sharp PL spectrum was located at the limited domain of UV, which covered the entire visible range for the different investigated samples, i.e., undoped and Cr-doped ZnO samples (Figure 5). The PL band located in the UV-domain could be attributed to both the free exciton recombination affecting the near band emission [43] and the donor-acceptor transition [14,[44][45][46][47]. Such a band is kept at the same energy position, which is in good agreement with the weak change of the band gap energy Eg with Cr doping as was reported in our previous work [11].…”

Cost-Effective and Efficient Cool Nanopigments Based on Oleic-Acid-Surface-Modified ZnO Nanostructured

“…Among such nanoscale materials is zinc oxide (ZnO) ceramic of II–VI oxides. Generally, ZnO and ZnO-based compounds have received much attention due to their extensive applications [ 1 , 2 ]. Evidently, these extensive applications of ZnO are the result of its valuable properties.…”

“…Such types of applications require materials with a high NIR reflection, such as ZnO, in order to use them in cool painting for exterior surfaces. Such paintings have an excellent impact on the reduction in the energy required for cooling [ 2 ].…”

Preparation and Chromaticity Control of CoTiO3/NiTiO3 Co-Coated TiO2 Composite Pigments

“…However, most inorganic pigments contain toxic elements such as heavy metals, making inorganic pigments not only costly, but also have adverse effects on human health and the environment, which severely restricts their development [6][7][8]. Therefore, the pigment industry necessitates the development of new inorganic pigments or the improvement of existing technology to eliminate or greatly reduce the harmful effects of toxic elements on human health in conventional inorganic pigments [9][10][11][12][13][14][15].…”