Synthesis of zinc oxide nanostructures on graphene/glass substrate by electrochemical deposition: effects of current density and temperature

Abstract

The electrochemical growth of zinc oxide (ZnO) nanostructures on graphene on glass using zinc nitrate hexahydrate was studied. The effects of current densities and temperatures on the morphological, structural, and optical properties of the ZnO structures were studied. Vertically aligned nanorods were obtained at a low temperature of 75°C, and the diameters increased with current density. Growth temperature seems to have a strong effect in generating well-defined hexagonal-shape nanorods with a smooth top edge surface. A film-like structure was observed for high current densities above -1.0 mA/cm2 and temperatures above 80°C due to the coalescence between the neighboring nanorods with large diameter. The nanorods grown at a temperature of 75°C with a low current density of -0.1 mA/cm2 exhibited the highest density of 1.45 × 109 cm-2. X-ray diffraction measurements revealed that the grown ZnO crystallites were highly oriented along the c-axis. The intensity ratio of the ultraviolet (UV) region emission to the visible region emission, IUV/IVIS, showed a decrement with the current densities for all grown samples. The samples grown at the current density below -0.5 mA/cm2 showed high IUV/IVIS values closer to or higher than 1.0, suggesting their fewer structural defects. For all the ZnO/graphene structures, the high transmittance up to 65% was obtained at the light wavelength of 550 nm. Structural and optical properties of the grown ZnO structures seem to be effectively controlled by the current density rather than the growth temperature. ZnO nanorod/graphene hybrid structure on glass is expected to be a promising structure for solar cell which is a conceivable candidate to address the global need for an inexpensive alternative energy source.

Shape controlled growth of ZnO nanorods and fabrication of ZnO/CuO heterojunctions by chemical bath deposition using zinc nitrate hexahydrate and copper (III) nitrate trihydrate

“…We have also reported the successful growth of vertically aligned ZnO NRs on graphene/glass substrates by ED [30]. It was also confirmed that the optical properties and diameters of the NRs can be effectively controlled by the current density during the deposition process [31]. Moreover, the cone-shaped ZnO NRs/CuO heterojunctions with rectifying behaviors on their J-V curves were successfully grown on the Au seed layers by CBD using Zn(CH 3 COO) 2 · 2H 2 O and copper (II) nitrate trihydrate [Cu(NO 3 ) 2 · 3H 2 O] [32].…”

The Relationship between the Mechanism of Zinc Oxide Crystallization and Its Antimicrobial Properties for the Surface Modification of Surgical Meshes

“…A significant advantage of this material is that its properties are strongly correlated with its size and morphology. For this reason, zinc oxide particles can be found in the literature in many forms, such as wires, tubes, belts, sheets, and rods [9], on different inorganic [10] or organic [11] substrates. In the case of ZnO application as an antibacterial [12], photocatalytic [13], or sensing material [14], a high surface area is crucial.…”

Field emission properties of ZnO nanosheets grown on a Si substrate

“…ZnO nanostructures have been extensively investigated owing to their remarkable physical and chemical properties that can be exploited in various electronic devices and optoelectronic devices. ZnO nanostructures with various geometrical morphologies have been developed using various synthetic methods, such as chemical vapor deposition [9], the hydrothermal method [10], pulsed laser deposition [11], and furnace and electrochemical deposition [12][13]. Various 1-D ZnO nanostructures, such as nanopins [14], nanorods [15], nanotubes and nanowires [16][17], as well as 2-D ZnO nanosheets [18], nanodiscs and nanoplates [19][20], have been fabricated.…”