Effect of seed particle size and ammonia concentration on the growth of ZnO nanowire arrays and their photoconversion efficiency

Influence of ammonia concentration on the microstructure, electrical and raman properties of low temperature chemical bath deposited ZnO nanorods

“…to precipitate quickly and eventually results in the fast consumption of the nutrient thus prohibiting the oriented growth of the nanorods [18]. Kwon et al [27] reported that further addition of ammonia solution induces the formation of amine complexes as shown in equation 4which precipitates in the solution. When this precipitation exceeds the number of nuclei, mult-angular orientated building blocks will grow on seeded substrates.…”

Ammonia-Induced Seed Layer Transformations in a Hydrothermal Growth Process of Zinc Oxide Nanowires

“…The application field of single-crystalline zinc oxide (ZnO) nanowires has recently been extended from the previous optics and electronics to the newly emerging nano-bio analysis due to their various fascinating features including the wide direct band gap, , large exciton binding energy, − piezoelectricity, , Lewis acidity, , high isoelectric point, and biocompatibility. , Thanks to such a variety of features, unique devices including light-emitting diodes (LEDs), nanogenerators, biochemical sensors, and biomedical analysis devices have been developed so far using ZnO nanowires. − A hydrothermal synthesis is among the most broadly utilized techniques for fabricating ZnO nanowires. − This is because the hydrothermal process is conducted at a temperature of less 100 °C and the diameter and position of nanowires are designable via seed crystals. These allow us to integrate ZnO nanowires with various materials and devices on a substrate. , Fundamentally, the anisotropic crystal growth of ZnO nanowires originates from a preferential nucleation on the ZnO(0001) plane, which is dominated by zinc hydroxide complex (Zn­(OH) n ) precursors. − Ammonia is a well-known additive to promote the growth of ZnO nanowires. − Such an effect of ammonia has been interpreted in terms of the variations of ionic species in aqueous solution and their electrostatic interactions with ZnO crystal planes. , A recent study by Sakai et al has further revealed that the increase of growth rate is mainly due to the change of the rate-limiting process from the precursor diffusion process to the ligand-exchange process, which is caused by the decreased concentration of Zn­(OH) n . On the other hand, ammonia causes a dissociation of ZnO during the nanowire growth.…”

Tailoring ZnO nanowire crystallinity and morphology for label-free capturing of extracellular vesicles

“…For controlling the morphology of ZnO nanowires, we introduced ammonia solution into the ZnO precursor growth solution during the growth step and hydrothermally fabricated nanowires in varying growth duration times for 3, 6, and 9 h. Ammonium hydroxide is an additive that has been widely used to enhance the nanowire growth rate along the c -axial ZnO plane via face-selective electrostatic crystal growth inhibition. 25 As ammonia concentration was reported to critically affect the morphology of nanowires, 26,44,45 we evaluated the optimum concentration of ammonia for our experimental conditions and found the concentration of ammonia at 0.8 M provided the longest nanowires (Fig. S1†).…”

“…Several studies have investigated physicochemical properties of the developed high aspect ratio ZnO nanowires in various applications including photocatalysis, a piezoelectric transducer, a UV detector, photovoltaic devices, and gas and chemical sensors. 26–31 To the best of our knowledge, the correlation of ZnO nanowires in terms of crystal structure and morphology with biomolecule capture has not been discussed until now.…”