Zinc oxide epitaxial thin film deposited over carbon on various substrate by pulsed laser deposition technique

Structural, optical and antibacterial investigation of La, Cu dual doped ZnO nanoparticles prepared by co-precipitation method

La, Cu dual doped ZnO with Cu = 0%-4% were prepared by co-precipitation route. The XRD pattern optimized the Cu content as 2% which restrict the secondary phase formation. The new phase at 38.7° corresponding to CuO (111) and the another phase at 42.3° related to Zn (101) came from un-reacted Zn²⁺ ions appeared in Cu = 4% doped sample. Zeta potential measurements confirms the stability of the particles. The blue shift of absorption edge and the energy gap from 3.66 eV to 3.99 eV by Cu doping was discussed by the shape of the particles, the distortion of the host lattice and generation of defect concentrations. The characteristic IR peaks around 470-489 cm^-1 was related to the octahedral sites of Zn-O for Cu = 0 and 2% which is shifted to 616 cm^-1 corresponding to the tetrahedral site at Cu = 4%. The shift in frequency was originated from the dissimilarity in the volume and bond lengths by the substitution of La and Cu in Zn-O. Based on the antibacterial report, it can be concluded that the Cu-doped Zn-La-O solid solution compose an effectual antimicrobial agent against pathogenic microorganisms. Cu = 4% doped sample possessed highest bacterial killing capacity because of the enhanced crystallite size and high density of oxygen vacancies which led the higher ROS values. Tuning of crystallite size and energy gap and the enhanced bactericial killing capacity by Cu addition is useful for opto-electronic device and medical applications.

Mn Doped AIZS/ZnS Nanocrystals: Synthesis and Optical Properties

In this work, Mn doped AIZS/ZnS (Mn:AIZS/ZnS) nanocrystals (NCs) have been synthesized in an approach using heat-up and drop-wise addition of precursors. On the basis of the characterization of these doped NCs on their optical properties and materials, it is found that: (1) as more Mn atoms are doped into NCs, the doped NCs present photoluminescence (PL) red-shift and quantum yield quenching; (2) the doped NCs possess a short PL lifetime in tens of microseconds and a long PL lifetime in hundreds of microseconds, and the short lived PL is more dominant than the long lived one; and (3) the doped NCs present a reversible PL thermal quenching in a range from room temperature to 170°C. Possible PL mechanisms of these NCs were discussed by analyzing their time-resolved PL spectra and thermal stability.

Well-Aligned Graphene Oxide Nanosheets Decorated with Zinc Oxide Nanocrystals for High Performance Photocatalytic Application

Graphene oxide (GO) nanosheets modified with zinc oxide nanocrystals were achieved by a green wet-chemical approach. As-obtained products were characterized by XRD, Raman spectra, XPS, HR-TEM, EDS, PL and Photocatalytic studies. XRD studies indicate that the GO nanosheet have the same crystal structure found in hexagonal form of ZnO . The enhanced Raman spectrum of 2D bands confirmed formation of single layer graphene oxides. The gradual photocatalytic reduction of the GO nanosheet in the GO : ZnO suspension of ethanol was studied by using X-ray photoelectron (XPS) spectroscopy. The nanoscale structures were observed and confirmed using high resolution transmission electron microscopy (HR-TEM). The evolution of the elemental composition, especially the various numbers of layers were determined from energy dispersive X-ray spectra (EDS). PL properties of GO : ZnO nanosheet were found to be dependent on the growth condition and the resultant morphology revealed that GO nanosheet were highly transparent in the visible region. The photocatalytic performance of GO : ZnO nanocomposites was performed under UV irradiation. Therefore, the ZnO nanocrystals in the GO : ZnO composite could be applied in gradual chemical reduction and consequently tuning the electrical conductivity of the graphene oxide nanosheet.

Cytotoxicity of cultured macrophages exposed to antimicrobial zinc oxide (ZnO) coatings on nanoporous aluminum oxide membranes

Zinc oxide (ZnO) is a widely used commercial material that is finding use in wound healing applications due to its antimicrobial properties. Our study demonstrates a novel approach for coating ZnO with precise thickness control onto 20 nm and 100 nm pore diameter anodized aluminum oxide using atomic layer deposition (ALD). ZnO was deposited throughout the nanoporous structure of the anodized aluminum oxide membranes. An 8 nm-thick coating of ZnO, previously noted to have antimicrobial properties, was cytotoxic to cultured macrophages. After 48 h, ZnO-coated 20 nm and 100 nm pore anodized aluminum oxide significantly decreased cell viability by ≈65% and 54%, respectively, compared with cells grown on uncoated anodized aluminum oxide membranes and cells grown on tissue culture plates. Pore diameter (20–200 nm) did not influence cell viability.