Hydrothermal−Electrochemical Synthesis of ZnO Nanorods

Abstract

Vertically aligned ZnO nanorods having high optical quality were prepared by a hydrothermal−electrochemical method. The nanorods were synthesized in a Zn(NO3)2 aqueous solution on Si substrates which were coated with a platinum conducting layer and a ZnO seed layer. They possessed a single-crystal würtzite structure and grew along the c-axis, perpendicular to the substrates. The height and diameter of the ZnO nanorods were up to ∼4.3 μm and 90−150 nm, respectively. The morphological, structural, and photoluminescence properties of the ZnO nanorods were examined with respect to the growth temperature (120−180 °C) and the presence of NaOH additive. The nanorods synthesized at high temperature (180 °C) exhibited a strong UV emission and a weak defect-related visible emission leading to a UV−visible ratio of ∼230. This high optical quality was attributed to the increased growth rate of ZnO nanorods (∼4.3 μm/h) which was caused by the high growth temperature (180 °C). This was based on the fact that the ZnO phase is thermodynamically more favorable than the defect-related Zn(OH)2 phase at higher temperature. Since the growth temperature was compatible with polymer materials, our synthetic method may provide a promising way for fabricating high performance optoelectronic devices on flexible polymer substrates.

Microwave-assisted synthesis of graphene–ZnO nanocomposite for electrochemical supercapacitors

“…It is clearly seen that the graphene sheets are decorated densely by small ZnO NPs. The diameter of ZnO NPs is estimated to be 5-10 nm and their crystalline structures can be observed clearly from the lattice fringes of the ZnO (0 0 2) plane with an interplanar spacing of approximately 0.52 nm and (1 0 0) plane with an interplanar distance of about 0.28 nm [44,45]. Additionally, the existence of Zn in the nanocomposite has been proved by the peaks of Zn in EDS data (Fig.…”

Enhanced photocatalytic degradation of methylene blue by ZnO-reduced graphene oxide composite synthesized via microwave-assisted reaction

“…The RGO nanosheets are curled and corrugated. The ZnO displays a hexagonal nanorod structure and its length and diameter decrease with the increase of RGO content in the composite, which implies that the presence of RGO inhibits the growth of ZnO nanorods [57]. It is observed that the RGO sheets with wrinkles and folds are decorated densely by the ZnO nanorods.…”

Porosity-induced full-range visible-light photodetection via ultrahigh broadband antireflection in ZnO nanowires

“…Moreover, during hydrothermal growth, residues from the organic precursor may be incorporated inside the ZnO NWs, which can be observed using XPS (Supplementary Figure S7 of the supporting information). [33][34][35][36] As the temperature rises above 450°C, these precursor residues decompose and evaporate, leaving the nanopores behind and thus forming internal pores. [34][35][36] To differentiate between the two types of pores, that is, the internal and external pores, a porous nanowire was rotated by tilting it inside the TEM (Figure 1c).…”