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Pandiyarajan, T., Mangalaraja, R. V., Karthikeyan, B., Arulraj, A., & Gracia-Pinilla, M. A. (2023). Fabrication and spectroscopic investigation of sandwich-like ZnO:rGO:ZnO: rGO:ZnO structure by layer-by-layer approach. Inorg. Chem. Commun., 149, 110383.
Abstract: Transparent conducting materials (TCMs) are the heart of modern optoelectronic industries and the properties of TCMs could be improved by the introduction of 2D carbon materials. In this report, the influence of order layering on microstructural, transparency and emission characteristics of ZnO:rGO:ZnO:rGO:ZnO and rGO:ZnO: rGO:ZnO:rGO sandwich structures has been investigated. The layer-by-layer approach has been adopted for the fabrication of sandwich structured materials ZnO:rGO:ZnO:rGO:ZnO and rGO:ZnO:rGO:ZnO:rGO through the spin coating technique. The sandwich structures of ZnO and rGO exhibited hexagonal wurtzite structure of ZnO without any impurities were identified through XRD. The ordering of layer's influenced the microstructural parameters and were significantly altered. The spherical nature of the particles and the formation of the sand-wich structures were confirmed by using SEM micrograph. The reduction in an optical transparency and nar-rowing bandgap of the ZnO upon the order of layering were identified through transmission spectra. The lower energy shift of near band edge (NBE) emission and reduction in the emission intensity with respect to pure ZnO nanostructures was observed. The present work provides a simple layer-by-layer approach to fabricating sand-wich structures and improving the optical properties which have potential applications in various optoelectronic devices.
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Sahlevani, S. F., Pandiyarajan, T., Arulraj, A., Valdes, H., Sanhueza, F., Contreras, D., et al. (2024). Tailored engineering of rod-shaped core@shell ZnO@CeO2 nanostructures as an optical stimuli-responsive in sunscreen cream. Mater. Today Commun., 38, 107959.
Abstract: The catalytic efficiency of the materials can be boosted with the selective designing (nanostructures) including the core@shell which aids in attaining the separation of photoinduced charge carriers. However, to effectively separate the carriers and reduce the rate of recombination, tuning the thickness of the shell wall is a vital one. The one-dimensional (1D) rod-like shell wall-controlled ZnO@CeO2 core@shell structures were successfully prepared via co-precipitation and hydrothermal methods using the hexamethylenetetramine (HMTA) as a reagent. The CeO2 shell wall thickness was fine-tuned between 15 and 70 nm with a variation in the concentration of HMTA reagent. The results revealed that the concentration of HMTA played a significant role in the formation of ZnO@CeO2 core@shell structures and in tuning their thickness. The FE-SEM images evidenced the core-shell structures formation with the specific thickness and uniformity. The HR-TEM images confirmed the homogeneity and regular form of the shell thickness. The unit cell and crystallite size were identified from the XRD analysis. The constructed core-shell structures were further employed in the formula of the prototypes of sunscreen and their photoprotective performance was analyzed in the view to cut the solar light irradiation in a new sunscreen formulation. The developed core-shell ZnO@CeO2 structures showed the excellent optical absorption in both the UV as well as visible regions.
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