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Subject: search.filters.subject.ZnO nanostructures

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    Tailoring ZnO Nanostructures through Precursor Concentration and Hydrothermal Duration: A Pathway to Efficient Solar Water Splitting
    (2026-11-10)
    Borklom, Phanlapa
    ;
    Khemasiri, Narathon
    ;
    Jessadaluk, Sukittaya
    ;
    Rattanawarinchai, Prapakorn
    ;
    Kayunkid, Navaphun
    This work investigated the formation of ZnO nanostructures on ITO substrates prepared by self-seeding hydrothermal synthesis for photoelectrochemical ( PEC) water splitting applications. The hydrothermal parameters, precursor concentration and hydrothermal time, were varied to explore their influences on ZnO crystallinity, morphology, and PEC performance. The combinations of X-ray diffraction and field emission scanning electron microscopy revealed highly oriented ZnO nanostructures with diverse morphologies, including small granules, nanorods, dense films, and hexagonal platelets. Topographic profiling of the morphological parameters revealed complex relationships between synthesis conditions and nanostructure characteristics, highlighting the importance of considering aggregation phenomena in substrate-based growth. This aggregation led to deviations from conventional crystal growth theory predictions, particularly for grain density and diameter evolution. PEC performance evaluation identified ZnO nanorods as the optimal morphology, exhibiting a photocurrent density of 0.182 mA/cm² at 0 V vs. Ag/AgCl. Further enhancement was achieved by decorating ZnO nanorods with CdS nanoparticles, resulting in a six-fold increase in photocurrent density (1.2 mA/cm²). This improvement is attributed to expanded light absorption and improved charge separation at the CdS/ ZnO interface. Our findings demonstrate the potential of rationally designed ZnO-based nanostructures in the advancement of solar-driven water splitting technologies and provide valuable insights for optimizing PEC systems through precise control of hydrothermal synthesis parameters, consideration of substrate-induced aggregation, and strategies for photoelectrochemical (PEC) water splitting applications.
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    ZnO nanostructures synthesized by one-step sol-gel process using different zinc precursors
    (2024-01-01)
    SONGPANIT, Maneerat
    ;
    BOONYARATTANAKALIN, Kanokthip
    ;
    PECHARAPA, Wisanu
    ;
    MEKPRASART, Wanichaya
    Zinc oxide (ZnO) nanopowders have been widely applied in electronics, optics and photocatalytic applications depending on their morphological structure. In the bottom-up process, it is conceived that the different zinc precursors may result in different formations of ZnO nanostructures with exceptional morphology. This work focuses on ZnO material synthesized via the facile sol-gel synthesis using different zinc slat precursors, including zinc acetate, zinc nitrate, zinc sulphate, and zinc chloride. All zinc salt precursors were incorporated with sodium hydroxide and hexamethylenetetramine (HMTA) under mild thermal energy with consistent conditions to investigate ZnO formation. The as-prepared samples appeared in white powders with different aggregation features. The crystalline phase, surface morphologies, and element mapping of all ZnO samples were analyzed using X-ray diffraction technique (XRD) and field emission scanning electron microscope (FE-SEM). The chemical bonding structure of ZnO powders was characterized by Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. The specific surface area per volume of ZnO nanopowders obtained by different zinc salt precursors was analyzed by Brunauer-Emmett-Teller (BET) method. All ZnO samples obtained from various zinc salt precursors exhibited a high crystallinity of the wurtzite structure without other impurities. The structural properties of ZnO nanopowders demonstrated different sizes and structures with distinguished formation and aggregation depending on the zinc precursor basic strength being used.
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    MORPHOLOGICAL and PHYSICAL PROPERTIES of ZnO NANOSTRUCTURES GROWN on Sb-DOPED ZnO SEEDING FILMS ANNEALED under DIFFERENT ATMOSPHERES
    (2021-12-01)
    Sinornate, Wuttichai
    ;
    Mimura, Hidenori
    ;
    Pecharapa, Wisanu
    In this work, morphological and physical properties of pyramid-like ZnO nanostructures fabricated on Sb-doped ZnO seeding films annealed under different atmospheres are extensively studied. The Sb-doped ZnO seeding films were first prepared by sol-gel spin coating technique onto glass substrate then annealed in nitrogen, air and argon followed by low-temperature hydrothermal process for ZnO nanostructures fabrication. The morphological results exhibit the growth of pyramid-like ZnO nanostructure with increasing density of the ZnO nanostructures. The crystal structure shows pyramid-like ZnO wurtzite hexagonal growth along the c-axis without any impurity phase. The growth of pyramid-like ZnO nanostructures is due to the high growth rate of (002) plane. Photoluminescence spectra exhibit the near-band-edge of all samples while the red emission appears in ZnO nanostructures after the hydrothermal process due to the imperfection in the crystal. The reflectance of ZnO nanostructures covers the visible region with the absorption edge of 375nm. The calculation shows the relevant energy band gaps in the range of 3.26-3.28eV. The difference in hydrothermally grown ZnO nanostructures is significantly affected by different annealing atmospheres.