HerewereportalowcostelectrochemicalaqueoussolutionmethodforsynthesisofhighqualitytwodimensionalflatZnOnano-sheets using standard home use microwave-oven. Independent studies by field emission scanning electron microscopy and high resolution transmission electron microscopy confirm the formation of very thin graphene-like nanosheets of ZnO. The high quality of the sheets is confirmed from a photoluminescence study, which shows the presence of a narrow and sharp band edge emission at 360 nm and the presence of a weak defect related emission peak in the visible region. The conductivity of the nanosheets increases dramatically upon illumination of UV lights as compared to the dark condition. The better crystal quality and excellent photo conductivity ensure these ZnO nanosheets can be used as potential UV detector. It is also found that both response and recovery times of ZnO nano-sheets are very fast and are comparable to those of nanowires and nanorods.

http://ma.ecsdl.org/content/MA2012-02/3/259.full.pdf

Synthesis of ZnO Nano-Sheets and Their Application in UV-Detector

In this research study, a thermal treatment approach based on a novel single-step has been utilised to addresses the synthesis of binary N i O 0.5 C r 2 O 3 0.5 nanoparticles. Characteristics of these binary metal oxide nanoparticles were examined by employing appropriate characterization tools. Sample patterns of X-ray diffractions were used, calcined with temperature ( Temp ), set to 500 °C revealed the existence of face-centred cubic (fcc) and hexagonal crystalline structures (hcs). It was noted that with a rising calcination temperature, the nanoparticle dispersal was enhanced further. On the other hand, TEM micrographs have been used to calculate the size of the mean particle. It was found that there was a rising tendency with the increased calcination temperature and this the growth of the mean particle. Increased particle size inherited a rise of nanoparticles' photoluminescence intensity, as suggested by recorded spectra, and various energy band gaps. This result would have been reduced as an effect once calcination temperature was increased. Resulting N i O 0.5 C r 2 O 3 0.5 nanoparticles could be used in the realm of semiconductors and energy applications.

Morphological, structural and optical behaviour of PVA capped binary (NiO)0.5 (Cr2O3)0.5 nanoparticles produced via single step based thermal technique

This study aims to synthesize the (Cr2O3)x (NiO)1-x nanoparticles at lower and higher precursor values using the calcination method. There is a lack in regard to investigating the lower and higher precursor values on structural and optical properties of the (Cr2O3)x (NiO)1-x nanoparticles. To synthesize the (Cr2O3)x (NiO)1-x nanoparticles, Cr (III) acetate hydrate and Ni (II) acetate tetrahydrate were reacted with poly (vinyl alcohol). Several techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR), have been employed to characterize the synthesized sample. The XRD pattern analysis indicated that, following calcination, nanoparticle formation occurred, indicating hexagonal crystalline structures (HCP) and face-centred cubic (FCC) of (Cr2O3)x (NiO)1-x nanoparticles. FT-IR verified the existence of Ni–O and Cr–O as the original compounds of ready (Cr2O3)x (NiO)1-x nanoparticle samples. In term of average particle size, this varied from 5 to 16 nm when the precursor concentration rised from x = 0.20 to x = 0.80, as reflected in the TEM results. X-ray photoelectron spectroscopy (XPS) was employed to measure the valence state and surface composition of the prepared product nanoparticles. To identify the optical band gap using the Kubelka–Munk equation, diffuse UV–visible reflectance spectra were employed, which revealed that the energy band gap fell with a rise in the value of x. In addition, photoluminescence (PL) spectra indicated that the photoluminescence intensity was related to a directly proportional way to particle size. Hence, the results can be employed with a broad range of applications in solar cell energy applications at higher x values and antibacterial activity at lower x values.

Nanofabrication of (Cr2O3)x (NiO)1-x and the impact of precursor concentrations on nanoparticles conduct

In the present work, a thermal treatment technique is applied for the synthesis of CexSn1−xO2 nanoparticles. Using this method has developed understanding of how lower and higher precursor values affect the morphology, structure, and optical properties of CexSn1−xO2 nanoparticles. CexSn1−xO2 nanoparticle synthesis involves a reaction between cerium and tin sources, namely, cerium nitrate hexahydrate and tin (II) chloride dihydrate, respectively, and the capping agent, polyvinylpyrrolidone (PVP). The findings indicate that lower x values yield smaller particle size with a higher energy band gap, while higher x values yield a larger particle size with a smaller energy band gap. Thus, products with lower x values may be suitable for antibacterial activity applications as smaller particles can diffuse through the cell wall faster, while products with higher x values may be suitable for solar cell energy applications as more electrons can be generated at larger particle sizes. The synthesized samples were profiled via a number of methods, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). As revealed by the XRD pattern analysis, the CexSn1−xO2 nanoparticles formed after calcination reflect the cubic fluorite structure and cassiterite-type tetragonal structure of CexSn1−xO2 nanoparticles. Meanwhile, using FT-IR analysis, Ce-O and Sn-O were confirmed as the primary bonds of ready CexSn1−xO2 nanoparticle samples, whilst TEM analysis highlighted that the average particle size was in the range 6−21 nm as the precursor concentration (Ce(NO3)3·6H2O) increased from 0.00 to 1.00. Moreover, the diffuse UV-visible reflectance spectra used to determine the optical band gap based on the Kubelka–Munk equation showed that an increase in x value has caused a decrease in the energy band gap and vice versa.

The Effect of Precursor Concentration on the Particle Size, Crystal Size, and Optical Energy Gap of CexSn1-xO2 Nanofabrication.

What paved way to the innovation of this research work is the ability to investigate the constituents of nanomaterials, which consist of inorganic and organic nanoparticles and organic polymers, considered as a brand-new classification of materials. A unique material is produced through this process which contains organic and inorganic nanoparticles and organic polymers. These materials exhibit improved characteristics when compared with their respective nanoscale size. In the present study, binary oxide (zinc oxide (ZnO))0.2 (zirconia oxide (ZrO2))0.8 nanoparticles (NPs) at constant concentration of polyvinylpyrrolidone (PVP), calcined at various temperatures were prepared by heat treatment technique. Zinc and zirconium nitrates (source of zinc and zirconium) with PVP (capping agent) was used to set up (ZnO)0.2 (ZrO2)0.8 NPs materials. Characterization of the materials was performed using the following analyses: thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and photoluminescence (PL). Thermal analysis (TGA) grants the optimization of the heat treatment technique and shows the required temperature for calcination to occur. XRD pattern analysis demonstrated that nanoparticles obtained after calcination indicated a hexagonal crystalline pattern of ZnO and tetragonal crystalline pattern of ZrO2 NPs. The FTIR spectroscopy phase analysis confirmed ZnO and ZrO2 are the original compounds of the prepared (ZnO)0.2 (ZrO2)0.8 NPs, respectively. TEM results indicated an increase in the average size of the sample from 21 to 29 nm due to increment in calcination temperature. Furthermore, PL spectra showed an increase in the intensity of PL as the particle size increased. The research work also looked at the optical application among the widespread applications of nanosized particles, binary oxide (ZnO)0.2 (ZrO2)0.8 as a new functional material.

Tafida Rabiu Abubakar

Papers

Structural, morphological and optical properties of (ZnO) 0.2 (ZrO 2 ) 0.8 nanoparticles