Growth Of Nanorods Research Articles

Highly efficient Zinc Oxide nanostructure based gas sensor for domestic application

In this work, Zinc Oxide (ZnO) nanorods with high surface to volume ratio were fabricated through the hydrothermal synthesis process on a glass slide and highly conductive alumina ceramic based gold interdigitated electrode (IDE). The ZnO nanorods structure on substrates were characterized through X-ray diffraction (XRD) and UV absorption spectroscopy followed by growth verification by Scherrer’s equation. The sensitivity characterization of fabricated sensor was determined for 2000 ppm and 4000 ppm natural gas in the air through high resistance electrometer at room temperature. The 2000 ppm concentration of gas shows 11.3% sensitivity, response time of 66 seconds and recovery time of 92 seconds to the sensor. The 4000 ppm concentration of gas shows 64% sensitivity, the response time of 106 seconds and a recovery time of 174 seconds to the sensor. The higher sensitivities with slow response and recovery times exhibit the behavior of redox reactions of sensor surface to the higher concentration of natural gas. The minute reduction in resistance and with the fast response and recovery time of the sensor show the 11.3% sensitivity to lower concentration. The more concentration of natural gas in the air would show a higher sensitivity of the sensor. The experimental results indicate the growth of ZnO nanorods on substrates and their sensitivity to natural gas.  Â

Rapid growth of zinc oxide nanorods on kanthal wires by direct heating method and its photocatalytic performance in pollutants removal

Immobilization of photocatalysts on supporting substrates to prevent the loss and deterioration of photocatalytic performances is an issue to be addressed by researchers. However, the common synthesis techniques such as chemical vapour deposition, sol-gel, or hydrothermal are time- and cost inefficient. A lot of heat is loss to environment when the heat generated outside the reactor is transferring into the reactor and precursor solution. In this work, ZnO nanorods were grown on kanthal wires using direct heating (DH) technique. DH technique offers many advantages as compared to common synthesis techniques such as chemical vapor deposition, sol–gel and hydrothermal to produce ZnO nanorods. The heat was generated directly on the substrate itself, providing effective heating, low electric consumption (≤0.060 kWh), and rapid synthesis (15 min) of ZnO nanorods. The presence of ZnO nanorods on kanthal wires are verified by XRD, FESEM, TEM/HRTEM, XPS and RTPL analyses. The ZnO nanorods demonstrated good photocatalytic performance in degradation of RhB dye and heavy metal ions under UV light. Thus, DH is a potential synthesis technique for mass production of wastewater treatment module.

Comb-shaped Sb2S3 nanorod arrays on ZnO nanofibers for thin-film photovoltaics

A hierarchical composite of Sb2S3 nanorods grown on zinc oxide (ZnO) nanofiber was prepared, and the formation of comb-shaped Sb2S3 nanorod arrays on the ZnO nanofibers was confirmed. It was found that the size of the diameter and the density of the nanorods are regulatable by changing the concentration of polyvinyl pyrrolidone as an additive for the growth of Sb2S3 nanorod on ZnO nanofiber. The obtained Sb2S3 nanorod arrays were applied as a light absorber for thin-film solar cells composed of glass-fluorine-doped tin oxide/compact ZnO/ZnO nanofibers−ZnS/Sb2S3 nanorod arrays/poly(3-hexylthiophene-2,5-diyl)/MoOx/Ag. The rectification ratio and photocurrent generation efficiency of the comb-shaped Sb2S3 nanorod arrays were improved as compared with the heterojunction of randomly stacked Sb2S3 nanorods. Smaller series resistance (Rs) of 8.13 Ω cm−2 and an ideality factor (n) of 2.84 with the comb-shaped Sb2S3 nanorod arrays than those of the randomly stacked ones of Rs = 15.01 Ω cm−2 and n = 3.83 also indicated superior charge extraction property and suppressed recombination of the comb-shaped Sb2S3 nanorod arrays at the interface.

Self-Induced Core-Shell InAlN Nanorods: Formation and Stability Unraveled by Ab Initio Simulations.

By addressing precursor prevalence and energetics using the DFT-based synthetic growth concept (SGC), the formation mechanism of self-induced InAlN core-shell nanorods (NRs) synthesized by reactive magnetron sputter epitaxy (MSE) is explored. The characteristics of In- and Al-containing precursor species are evaluated considering the thermal conditions at a typical NR growth temperature of around 700 °C. The cohesive and dissociation energies of In-containing precursors are consistently lower than those of their Al-containing counterparts, indicating that In-containing precursors are more weakly bonded and more prone to dissociation. Therefore, In-containing species are expected to exhibit lower abundance in the NR growth environment. At increased growth temperatures, the depletion of In-based precursors is even more pronounced. A distinctive imbalance in the incorporation of Al- and In-containing precursor species (namely, AlN/AlN+, AlN2/AlN2 +, Al2N2/Al2N2 +, and Al2/Al2 + vs InN/InN+, InN2/InN2 +, In2N2/In2N2 +, and In2/In2 +) is found at the growing edge of the NR side surfaces, which correlates well with the experimentally obtained core-shell structure as well as with the distinctive In-rich core and vice versa for the Al-rich shell. The performed modeling indicates that the formation of the core-shell structure is substantially driven by the precursors' abundance and their preferential bonding onto the growing edge of the nanoclusters/islands initiated by phase separation from the beginning of the NR growth. The cohesive energies and the band gaps of the NRs show decreasing trends with an increment in the In concentration of the NRs' core and with an increment in the overall thickness (diameter) of the NRs. These results reveal the energy and electronic reasons behind the limited growth (up to ∼25% of In atoms of all metal atoms, i.e., In x Al1-x N, x ∼ 0.25) in the NR core and may be qualitatively perceived as a limiting factor for the thickness of the grown NRs (typically <50 nm).

Morphological and Optical Transitions during Micelle-Seeded Chiral Growth on Gold Nanorods.

Chiral plasmonics is a rapidly developing field where breakthroughs and unsolved problems coexist. We have recently reported binary surfactant-assisted seeded growth of chiral gold nanorods (Au NRs) with high chiroptical activity. Such a seeded-growth process involves the use of a chiral cosurfactant that induces micellar helicity, in turn driving the transition from achiral to chiral Au NRs, from both the morphological and the optical points of view. We report herein a detailed study on both transitions, which reveals intermediate states that were hidden so far. The correlation between structure and optical response is carefully analyzed, including the (linear and CD) spectral evolution over time, electron tomography, the impact of NR dimensions on their optical response, the variation of the absorption-to-scattering ratio during the evolution from achiral to chiral Au NRs, and the near-field enhancement related to chiral plasmon modes. Our findings provide further understanding of the growth process of chiral Au NRs and the associated optical changes, which will facilitate further study and applications of chiral nanomaterials.

Detection of 2-ethyl hexanol and dioctyl phthalate with potentiometric sensor based on ordered ZnO nanorods sensing electrode

In this work, a planar mixed-potential sensor was prepared by in situ growth of ZnO nanorods sensing electrode on yttria-stabilized zirconia (YSZ) electrolyte. The potentiometric sensing properties of the sensor toward two signature gases of early PVC cable fires, 2-ethyl hexanol (2-EH) and dioctyl phthalate (DOP), were studied. High response values of −205.1 mV and −54.1 mV were achieved at 400 °C for ∼171–193 ppm 2-EH and ∼89–109 ppt DOP for ZnO nanorods-based sensor, which were 1.7 and 4.1 times higher than those of ZnO nanoparticles-based sensor, respectively. Furthermore, ZnO nanorods exhibited much better 2-EH and DOP selectivity. The improvement of the gas-sensing performance of ZnO nanorods may be ascribed to the unique three-dimensional electrode morphology.

Asymmetric Interfacet Adatom Migration as a Mode of Anisotropic Nanocrystal Growth.

Crystals are known to grow nonclassically or via four classical modes (the layer-by-layer, dislocation-driven, dendritic, and normal modes, which generally involve minimal interfacet surface diffusion). The field of nanoscience considers this framework to interpret how nanocrystals grow; yet, the growth of many anisotropic nanocrystals remains enigmatic, suggesting that the framework may be incomplete. Here, we study the solution-phase growth of pentatwinned Au nanorods without Br, Ag, or surfactants. Lower supersaturation conditions favored anisotropic growth, which appeared at variance with the known modes. Temporal electron microscopy revealed kinetically limited adatom funneling, as adatoms diffused asymmetrically along the vicinal facets (situated inbetween the {100} side-facets and {111} end-facets) of our nanorods. These vicinal facets were perpetuated throughout the synthesis and, especially at lower supersaturation, facilitated {100}-to-vicinal-to-{111} adatom diffusion. We derived a growth model from classical theory in view of our findings, which showed that our experimental growth kinetics were consistent with nanorods growing via two modes simultaneously: radial growth occurred via the layer-by-layer mode on {100} side-facets, whereas the asymmetric interfacet diffusion of adatoms to {111} end-facets mediated longitudinal growth. Thus, shape anisotropy was not driven by modulating the relative rates of monomer deposition on different facets, as conventionally thought, but rather by modulating the relative rates of monomer integration via interfacet diffusion. This work shows how controlling supersaturation, a thermodynamic parameter, can uncover distinct kinetic phenomena on nanocrystals, such as asymmetric interfacet surface diffusion and a fundamental growth mode for which monomer deposition and integration occur on different facets.

In situ synthesis of clustered bimetallic metal-organic frameworks on Bi-pyrene terminated molecular wire modified graphene for supercapacitors

Metal-organic frameworks (MOFs) have been widely utilized for catalytic and sensing fields in recent years due to their high specific surface area and large porosity. However, the low electrical conductivity and unsatisfactory capacitance hinder their wide application in the field of energy storage devices. Given by its excellent electrical conductivity, large specific surface area, introduction of graphene into composite materials can significantly improve their electrical conductivities. Herein, we have successfully designed and fabricated CoCe-MOF@rGO/BPMW-300 hybrid through in situ growth of CoCe-MOF nanorods on Bi-pyrene terminated molecular wire (BPMW) modified graphene by hydrothermal and annealing processes. The synergistic effect of Co and Ce elements solves the disadvantage of low conductivity of MOF materials. The modification of BPMW can avoid graphene aggregation and help build abundant electron transport channels, which significantly improve the electrochemical performance of the entire material. The CoCe-MOF@rGO/BPMW-300, which is utilized as the cathode in three-electrode system, exhibits superior electrochemical performance with specific capacity of 1554 F g−1 under the current density of 1 A g−1.

Growth and Structure of Single-Crystal ZnO Nanorods Codoped with Fe and Li for Multiferroic Applications

Growth and Structure of Single-Crystal ZnO Nanorods Codoped with Fe and Li for Multiferroic Applications

Chemically Synthesized ZnO Thin Film Electrode for Supercapacitor Application

In this paper, we synthesized zinc oxide (ZnO) thin film by using a cost effective chemical bath deposition technique (CBD) at 90∘C. The as-deposited ZnO films exhibited polycrystalline in nature. The FESEM image shows growth of nanorods about 0.2[Formula: see text][Formula: see text]m length. The Raman spectrum was recorded using frequency of 532[Formula: see text]nm with excited line Nd-YAG laser. The optical band gap of ZnO thin film obtained 3.37[Formula: see text]eV. The value of RMS roughness is determined by atomic force microscopy (AFM), found to be 34[Formula: see text]nm. The supercapactive studies were determined in 2[Formula: see text]M[Formula: see text]KOH aqueous electrolyte by means of cyclic voltammetry and charge–discharge technique. ZnO exhibited maximum specific capacitance of ZnO 204[Formula: see text]F/g at the scan rate of 5[Formula: see text]mV/s.

ZnO Nanorods Growth and the Parametric Survey of Factors Influencing the Morphologies for DSSC Application-Review

Zinc-oxide (ZnO) nanostructures, such as nanorods, are generally viewed as leading studies of keen interest due to their significant application potential in many applied areas, primarily for the improvement of photovoltaic solar cells. The morphologies of nanorods are linked to the seed layer (SL) optimization. As a result, forming a high-quality ZnO thin film prior to the growth of nanorods is critical. The processing parameters used during the synthesis technique can influence the quality of the synthesized samples. This review article focuses on the outcomes of the process variables responsible for better-synthesized ZnO SL for nanorod growth. The effect of various parameters, such as annealing temperature, precursor solution, and ZnO SL thickness, on the morphology characteristics of ZnO nanorods prepared was reviewed. The study examined numerous published works to find the effect of heat treatment, the thickness of the layer, substrate, and precursor concentration on the morphology of the seed layer in the production of ZnO nanorods.

Morphology Control of TiO2 Nanorods Using KBr Salt for Enhancing the Photocatalytic Activity of TiO2 and MoS2/TiO2 Heterostructures.

In this study, the effect of KBr salt on the growth of TiO2 nanorods (NRs) was systematically studied. The addition of KBr with different concentrations provides a controllable growth of TiO2 NRs using hydrothermal method. The results revealed that the presence of KBr molecules affects the growth rate by suppressing the growth in the lateral direction and allowing for axial growth. This results in affecting the morphology by decreasing the diameter of the nanorods, and increasing the free space between them. Enhancing the free spaces between the adjacent nanorods gives rise to remarkable increase in the internal surface area, with more exposure side surface. To obtain benefit from the enlargement in the inner surface area, TiO2 NRs were used for the preparation of MoS2/TiO2 heterostructures. To study the influence of the morphology on their activity, TiO2 NRs samples with different KBr concentrations as well as the MoS2/TiO2 heterostructures were evaluated towards the photocatalytic degradation of Rhodamine B dyes.

Role of Seed Layer Crystalline Quality in Photoresponse Performance of Hydrothermally Grown ZnO Nanorods.

We investigated the effects of the crystalline state for seed layers (SLs) on the growth morphology and material characteristics for hydrothermally grown ZnO nanorods (NRs). For this, preheating (PH) at different temperatures (100–300 °C) and O2 plasma treatment (PT) for 9 min were performed during the growth of SLs on p-Si by the aqueous solution-based method to provide the characteristic change on the NR growth platform. An improvement in material properties was achieved from the ZnO NRs grown on the SL crystals of enhanced crystalline quality in terms of the increased preferred orientation (002), the higher UV emission with suppressed deep-level emissions, the recovery of O/Zn stoichiometry, and the reduction of various intrinsic defects. Ultraviolet photodiodes of a p-Si/n-ZnO-NR structure fabricated under the SL conditions of O2 PT and PH at 100 °C showed a significantly enhanced on-off current ratio of ~90 at +5 V and faster photoresponse characteristics presenting a reduction in the fall time from 16 to 9 s.

Synthesis of Cesium Copper Bromide Nanorods with Strong Linearly Polarized Emission

AbstractSemiconductor nanorods have often been observed to emit polarized light. This property can be useful for emission applications such as displays, optical communications, and biological labeling. Recently, many researchers have tried to replace nanocrystals containing toxic metals, such as Cd or Pb, with alternatives that can also demonstrate polarized emission. Here a low temperature injection (LTI) method with a relatively short chain octylammonium bromide ligand precursor is used to slow down the nanorod formation reaction and the controlled anisotropic growth of Cs3Cu2Br5 nanorods is realized, producing more uniform samples of nanorods with higher aspect ratios than those previously reported. Such nanorods exhibit a very high degree of polarization (DOP) of 0.88 ± 0.04 for single rods, and a corresponding polarization anisotropy of 0.26 for the sample population, both the highest yet reported for any perovskite‐like material. Further this method can be extended to produce Cs3Cu2Cl5 nanorods as well, allowing for broad tuning of their optical properties.

ZnO Nanorods Coated Single-Mode-Multimode-Single-Mode Optical Fiber Sensor for VOC Biomarker Detection.

This work demonstrated a ZnO-coated optical fiber sensor for the detection of a volatile organic compound (VOC) biomarker for diabetes for detecting isopropanol (IPA) markers. A coreless silica fiber (CSF) was connected to a single-mode fiber (SMF) at both ends to achieve a SMF–CSF–SMF structure. CSF is the sensing region where multimode interference (MMI) generates higher light interaction at the interface between the fiber and sensing medium, leading to enhanced sensitivity. Optimization of the CSF length was conducted numerically to attain the highest possible coupling efficiency at the output. Surface functionalization was achieved via hydrothermal growth of ZnO nanorods directly onto the CSF at low temperatures. The optical fiber-based sensor was successfully fabricated and tested with 20%, 40%, 60%, 80%, and 100% of IPA. The sensor response was recorded using an optical spectrometer and analyzed for sensor sensitivity. The fabricated sensor shows the potential to detect isopropanol with the sensitivity of 0.053 nm/%IPA vapor. Further improvement of the sensor sensitivity and selectivity is also proposed for future work.

Piezo-photoelectric all-in-one coaxial hierarchical TiO2-BaTiO3-CuInS2 heterostructure for synergistic water splitting

Rational multiple-field coupling, component control, and microarchitectures design for utilization of multiform driving forces as well as benefiting charge-carrier separation and migration is considered to be an outstanding approach to improve water splitting efficiency for alleviating increasing environmental problems. Herein, a novel piezo-photoelectric catalyst, coaxial TiO2-BaTiO3-CuInS2 heterostructures, was designed for efficient hydrogen production, synergistically driven by mechanical force, electricity, and light. The vertical growth of TiO2 nanorods guarantees sufficient generation of photoinduced charges and their fast migration. Electric field generated by the piezoelectric BaTiO3 shell under a mechanical driving force will promote the separation and transfer of photogenerated charge carriers, thereby minimizing the probability of charge recombination. The further incorporation of the outermost layer of CuInS2 is beneficial to broaden light harvesting. Of particular importance is the cascade band arrangement of the three different functional components, which greatly enhances the transfer of photo- and piezoelectrically induced charges. With the synergy of enhanced light harvesting, energy band engineering, and nanostructure interfacial design, the fabricated TiO2-BaTiO3-CuInS2 photoelectrode has achieved significant enhancement of piezo-photoelectric hydrogen evolution efficiency and could be expanded for pollutant decomposition. This simple yet general strategy provides valuable guidance for cooperatively capitalizing on piezoelectricity to engineer high-performing energy conversion and environmental protection.

Silicate-Mediated Electrolytic Silicon Nanotube from Silica in Molten Salts.

Electrochemical preparation/processing of functional silicon from abundant silica is an ideal protocol to promote sustainability of energy sectors. Such an imperative task is challenged by poor electrical conductivity of Si/SiO2 and inadequate mass diffusion of bulk silicon. Herein, a template-free and one-step preparation of silicon nanotubes (Si-NT) from electrochemical reduction of silica in molten salts is reported. An in situ oriented growth of silicate nanorods (NRs) from silica is clarified as the key step to direct a self-template evolution of Si-NT from silica. The silicate-mediated construction of Si-based NT is versatile and successfully extended to prepare Si-NT/graphite and Tix Siy -NT. Benefitting from fast longitudinal motorways for fast transport of electrons and ions along/inside NTs, an energy consumption 30% lower than industrial silicon production is achieved. When evaluated as anode of lithium ion battery, the Si-NT-based electrodes show outstanding initial Coulombic efficiency and high reversible capacity. The silicate-mediated construction of Si-based NT integrates straightforward preparation and intriguing functionality of Si-based materials, bridging a closed-loop Si-based energy infrastructure.

Surface modified Ni wire supported flexible asymmetric supercapacitor of Mn3O4// PEDOT-PSS-MWCNT and its solar charging for self-powered Cu-doped ZnO nanorods-based UV photodetector

Recently, wire-shaped supercapacitors (WSCs) with the benefits of being flexible, lightweight, and wearable, have attracted great attention as portable and wearable power sources, though still, they face critical challenges of inadequate energy density and electrochemical stability under mechanical deformations. Therefore, we report the fabrication of the asymmetric WSC constituting surface-modified Ni wire as current collectors, PVA-KOH electrolyte, and hydrothermally grown Mn3O4 nanoflakes and dip-coated PEDOT: PSS-MWCNT nanocomposites as positive and negative electrode active materials, respectively. Owing to surface modification of Ni wire and active materials with approximate mass matching, mesoporous nanostructured surface morphology, and improved surface areas, the twisted asymmetric WSC exhibits excellent volumetric capacitance of 7.55 F/cm3, 2.69 mWh/cm3 energy density, and 95 mW/cm3 power density at 25 μA with a 1.6 V voltage window. In addition, considering the recent trend of developing multi-functional self-powered systems integrating energy harvesters, storage entities, and functional components, ultraviolet photodetector (UV PD) in metal-semiconductor-metal (MSM) configuration was fabricated by hydrothermal growth of Cu-doped ZnO nanorods onto interdigitated electrode printed glass substrate, and hence for the first time a self-powered UV-light detection system with a fast response and high on/off ratio were successfully demonstrated by connecting solar-charged parallel asymmetric WSCs and UV PD.

β-Ga2O3 Nanostructures: Chemical Vapor Deposition Growth Using Thermally Dewetted Au Nanoparticles as Catalyst and Characterization.

β-Ga2O3 nanostructures, including nanowires (NWs), nanosheets (NSHs), and nanorods (NRs), were synthesized using thermally dewetted Au nanoparticles as catalyst in a chemical vapor deposition process. The morphology of the as-grown β-Ga2O3 nanostructures depends strongly on the growth temperature and time. Successful growth of β-Ga2O3 NWs with lengths of 7–25 μm, NSHs, and NRs was achieved. It has been demonstrated that the vapor–liquid–solid mechanism governs the NW growth, and the vapor–solid mechanism occurs in the growth of NSHs and NRs. The X-ray diffraction analysis showed that the as-grown nanostructures were highly pure single-phase β-Ga2O3. The bandgap of the β-Ga2O3 nanostructures was determined to lie in the range of 4.68–4.74 eV. Characteristic Raman peaks were observed with a small blue and red shift, both of 1–3 cm−1, as compared with those from the bulk, indicating the presence of internal strain and defects in the as-grown β-Ga2O3 nanostructures. Strong photoluminescence emission in the UV-blue spectral region was obtained in the β-Ga2O3 nanostructures, regardless of their morphology. The UV (374–377 nm) emission is due to the intrinsic radiative recombination of self-trapped excitons present at the band edge. The strong blue (404–490 nm) emissions, consisting of five bands, are attributed to the presence of the complex defect states in the donor (VO) and acceptor (VGa or VGa–O). These β-Ga2O3 nanostructures are expected to have potential applications in optoelectronic devices such as tunable UV–Vis photodetectors.

Epitaxial Growth of Vertically Aligned Antimony Selenide Nanorod Arrays for Heterostructure Based Self‐Powered Photodetector

AbstractAntimony selenide (Sb2Se3) has garnered significant attention with its extraordinary optical and optoelectronic properties for optical and optoelectronic devices such as broadband photodetectors. The trends emerge in the synthesis of Sb2Se3 over a semiconducting substrate for the direct formation of heterostructures, which facilitate a pn junction for self‐powered photodetector. 1D Sb2Se3 nanorods are preferred to boost the charge carrier transport along the longitudinal direction as well as the optical absorption by light trapping. Great challenges remain for the vertical growth of nanorods. In this work, the precisely vertical alignment of Sb2Se3 nanorod arrays has been achieved in an epitaxial growth manner by selecting a lattice‐matching substrate, namely, boron‐doped ZnO (110) surface. The directly grown boron‐doped ZnO/Sb2Se3 nanorod arrays heterostructure leads to a high‐performance broadband photodetector. Eventually, the device demonstrates extraordinary figure‐of‐merit parameters, i.e., responsivity, on/off ratio, and specific detectivity. Furthermore, device simulation predicts the theoretical limit of the photodetector performances on the condition of suppressed defect density of the Sb2Se3. These results may shed light on the investigation of controlled growth of low‐dimensional materials, self‐powered photodetectors, and related optic and optoelectronic devices.