Growth Of ZnO Nanorods Research Articles

The Application of Ultrasound Pre-Treatment in Low-Temperature Synthesis of Zinc Oxide Nanorods

Zinc oxide, due to its unique physicochemical properties, including dual piezoelectric and semiconductive ones, demonstrates a high application potential in various fields, with a particular focus on nanotechnology. Among ZnO nanoforms, nanorods are gaining particular interest. Due to their ability to efficiently transport charge carriers and photoelectric properties, they demonstrate significant potential in energy storage and conversion, as well as photovoltaics. They can be prepared via various methods; however, most of them require large energy inputs, long reaction times, or high-cost equipment. Hence, new methods of ZnO nanorod fabrication are currently being sought out. In this paper, an ultrasound-supported synthesis of ZnO nanorods with zinc acetate as a zinc precursor has been described. The fabrication of nanorods included the treatment of the precursor solution with ultrasounds, wherein various sonication times were employed to verify the impact of the sonication process on the effectiveness of ZnO nanorod synthesis and the sizes of the obtained nanostructures. The morphology of the obtained ZnO nanorods was imaged via a scanning electron microscope (SEM) analysis, while the particle size distribution within the precursor suspensions was determined by means of dynamic light scattering (DLS). Additionally, the dynamic viscosity of precursor suspensions was also verified. It was demonstrated that ultrasounds positively affect ZnO nanorod synthesis, yielding longer nanostructures through even reactant distribution. Longer nanorods were obtained as a result of short sonication (1–3 min), wherein prolonged treatment with ultrasounds (4–5 min) resulted in obtaining shorter nanorods. Importantly, the application of ultrasounds increased particle homogeneity within the precursor suspension by disintegrating particle agglomerates. Moreover, it was demonstrated that ultrasonic treatment reduces the dynamic viscosity of precursor suspension, facilitating faster particle diffusion and promoting a more uniform growth of longer ZnO nanorods. Hence, it can be concluded that ultrasounds constitute a promising solution in obtaining homogeneous ZnO nanorods, which is in line with the principles of green chemistry.

Tailoring the morphological, optical, electrical, and random lasing properties of ZnO nanorods synthesized on metal surfaces for biosensor applications

Laser-based sensors are taking over their counterparts, fluorescence-based sensors, in the field of bioengineering and space communication due to their high amplification, narrow emission beam, low signal-to-noise ratio, and nonlinearity. In this work, we investigated the chemical growth of ZnO nanorods on different metal surfaces (Au, Pt, Ti, and Al) to serve as random laser mediums. Different analytical techniques were used to investigate the optical, electrical, and morphological properties of the fabricated devices. A lasing threshold of 27.68 mJ/cm² with a spectral width of 2.18 nm centered at 385.06 nm is observed when Ti is used as the growth surface. Al surface produces ZnO nanorods with a lasing threshold of 24.21 mJ/cm² and a spectral width of 1.81 nm. Growing ZnO nanorods on metal surfaces using the chemical bath deposition method paves the way for fabricating different random lasing-based biosensors.

In situ growth of oxygen vacancies-rich ZnO nanorods for N-methyl pyrrolidone sensors

N-methyl pyrrolidone (NMP) is an organic compound that is mainly used in chemical synthesis, the manufacture of anesthetics and pesticides, and the production of electronic materials, especially in the preparation of electrodes for lithium-ion batteries. However, their high volatility and toxicity pose potential risks to health and the environment. Therefore, the development of rapid, highly sensitive and low-cost NMP gas sensors is urgent. In this paper, ZnO nanorods were in situ grown on ceramic tubes via hydrothermal method and subsequently annealed at different temperatures. The gas sensing performance of ZnO nanorods after annealing at different temperatures was investigated. The results show that the ZnO nanorods annealed at 400 °C have more oxygen vacancies and excellent selectivity to NMP at 210 °C, with a response value of up to 67.33–100 ppm NMP, a response time of 25 s, and a low recovery time as low as 8 s. The sensors have potential applications for rapid monitoring of NMP and environmental health protection, providing a simple and feasible method for NMP detection.

The effect of seed layer cycles on the structural, optical, and morphological properties of ZnO nanorods.

In this study, ZnO seed layers with different cycles were formed on glass substrates by the sol-gel technique, and ZnO nanorods were grown on them by the hydrothermal method. Morphology and the structural characterization of the seed films and the ZnO nanorods are carried out by field emission scanning electron microscopy (FE-SEM) and x-ray diffraction techniques. In addition, to investigate the effect of seed layer deposition cycles on the optical properties of the ZnO nanorod arrays, UV/visible spectrophotometer and photoluminescence (PL) measurements were performed. The changes in structural and optical parameters such as dislocation density, strain, crystallite size, and optical band gap values on each seed layer deposition cycle were examined. The highest optical band gap and crystallite size were obtained for ZnO nanorods with 4 cycles seed layer as 3.22 eV and 63.6 nm, respectively. Also, in the PL spectrum, the largest ratio of UV-emission region to weak-visible emission region was obtained in ZnO nanorods having 4 cycles. In addition, the glucose detection properties of ZnO nanorods having 4 cycles were investigated using the PL measurements and it was found that UV-emission peak intensity of ZnO nanorods decreased as the glucose concentration increased from 8 to 40 mM. The results show that the number of deposition cycles of the seed layer has a strong influence on the orientation, crystal quality, and optical band gap of the growing ZnO nanorods, as well as significantly affecting their morphological properties. RESEARCH HIGHLIGHTS: High quality ZnO nanorods were grown on glass substrates by hydrothermal method. The effect of ZnO seed layer cycles on the structural, optical, and morphological characteristics of ZnO nanorods grown on were examined. It was found that the number of cycles of the seed layer is a critical parameter for growing quality and well-aligned ZnO nanorods.

Influence of Growth Temperature on Morphological and Structural Properties of Sputtered- Zinc Oxide Nanorods

Zinc oxide is highly sought after for several applications in biology, optoelectronics, electronics, and sensing. Zinc oxide nanorods exhibit a high exciton binding energy and a wide direct band gap, making them an attractive material for ultraviolet optoelectronic devices in the compound semiconductor field. This investigation focuses mainly on the influence of growing temperature on the crystal structure and surface morphology of ZnO nanorods, specifically for their application as UV photodetectors. Si (100) substrates were utilized for the growth of ZnO nanorods using radio frequency magnetron sputtering. The ZnO nanorods are grown at temperatures of 350 °C, 375 °C, and 400 °C, respectively. The crystal structure and surface morphology were examined using X-ray diffraction and scanning electron microscopy. The samples exhibited a same crystal orientation of the (002) diffraction peak at all growth temperatures. The growth temperatures show a direct influence on the density and length of nanorods, as evidenced by the scanning electron microscopy photographs. The results revealed the significant influence of substrate temperature on the regulation of nanorod length and crystal formation.

3D SERS substrate using silver nanoparticles decorated ZnO nanorods on silicon micropyramids hybrid heterostructure

3D hybrid heterostructure have been fabricated using Ag Nanoparticles decorated ZnO nanorods over textured Silicon Micropyramid for Surface Enhanced Raman Scattering (SERS) applications. Silicon texturing was performed using facile Alkaline texturing route followed by the growth of ZnO nanorods (ZnONR) array on the micropyramids over which, the Ag nanoparticles (AgNPs) were decorated. The phase and the surface of the heterostructure was studied by XRD and Field Emission Scanning Electron Microscope (FESEM), respectively. The SERS performance of the 3D heterostructure was evaluated using Rhodamine 6G (R6G) at various concentrations with a detection limit of 0.1 pM. The superior properties of SiMP/ZnONR/AgNP over ZnONR/AgND heterostructure has also been presented to understand the effect of the 3D pyramidal substrate for superior SERS performance. The recovery of the prepared heterostructure has also been demonstrated by photocatalytic degradation of Rhodamine 6G and Methylene Blue. Our work demonstrates a facile synthesis of 3D SERS heterostructure and sheds light on its superior SERS properties paving ways for wide range of applications in bio-sensors, detection of harmful chemicals, food adulterations, narcotic detection and many more.

The structure of epitaxial growth of Nb-doped ZnO nanorods on intrinsic substrate via sonicated aqueous chemical method

The simplicity and abundance of water sources make water-based synthesis extremely intriguing. Nb-doped ZnO nanorods was successfully grown using a straightforward and cost-effective aqueous chemical technique. The precursor of Nb-doped ZnO comprised zinc nitrate hexahydrate, hexamethylenetetramine (HMTA), and deionized water. These substances were used as starting materials, stabilisers, and solvents, respectively. Niobium chloride served as a source of niobium dopant. The intrinsic seeded substrate was submerged in a Nb-doped ZnO precursor solution in order to facilitate the epitaxial growth of nanorods. In order to investigate the influence of the dopant percentage, the amount of Nb-dopant was varied from 0 to 0.7 at. %. The presence of Nb-doped ZnO nanorods was confirmed by the utilisation of FESEM and EDAX techniques, which allowed for the verification of both the growth of nanorods and the identification of their constituent elements. The diameter obtained is between 79.76 and 134.51 nm, depending on the amount of dopant. Since the average nanorod length is 1.1086 ± 24.9187 μm, the aspect ratio estimation is about 13.9. The atomic arrangement was investigated using high-resolution transmission electron microscopy (HRTEM). The interplanar distance of 0.264 nm corresponds to plan (002) estimated via HRTEM. The estimation is in agreement with the XRD analysis. In addition, the peak of (002) is dominant for every sample. The sharpest and highest peak can be found in 0.3 at. % of dopant. As the texture coefficient (TC) has a higher value for plan (002), crystalline growth is preferred in c-orientation.

Altering defect population during the solvothermal growth of ZnO nanorods for photocatalytic applications

High abundance and low toxicity make zinc oxide very attractive for broad application in the field of photocatalysis for remediation of toxic compounds from water. Its performance could be elegantly improved by inducing native defects into ZnO semiconductor nanocrystals. However, this typically requires post-processing at high temperatures, during which many of the benefits of the original batch of monodisperse small grains are lost due to agglomeration and/or crystal growth. Within this research we show how variations in defect population are inherent to recrystallization process and that they can be tuned to some extent by choosing optimal pathways. The defects were studied by Raman, photoluminescence and EPR spectroscopy, while the surface chemistry of the ZnO nanorods, solvothermally recrystallized from ZnO nanodots, was evaluated by X-ray photoelectron spectroscopy. The produced nanorods with different dimensions were also utilized to show how effective the samples are for degradation of a model pollutant, namely caffeine. Unexpectedly, we found that the surface chemistry of our samples is not the main factor in photocatalytic efficiency. Instead, we show that the differences in photocatalytic activity are mainly determined by the defect population within the bulk formed during the recrystallization process under altered solvothermal conditions.

Removal of antibiotic sulfamethoxazole in water using rapid growing ZnO nanorod

The primary objective of this research is to synthesize ZnO vertical nanorods on a conductive substrate through a novel approach. In this method, ZnO nanorods are grown on kanthal wires using the direct heating (DH) technique. The study investigated the application of ZnO nanorods in photodegradation, specifically in removing Sulfamethoxazole (SMX). Through comprehensive analysis techniques, including XRD, FESEM, and TEM, the successful growth of ZnO nanorods on kanthal wires is confirmed. Their photocatalytic activity in SMX degradation is evaluated at varying concentrations (3 ppm, 5 ppm, 10 ppm) under UV light. Notably, the ZnO sample produced under 80 W power and 120 min emerges as the most promising, exhibiting a high surface area of 36 m2g-1, larger length of 755 nm, and lower diameter of 12 nm, as well as superior SMX photodegradation percentages of 87.64 % (3 ppm), 77.86 % (5 ppm), and 51.84 % (10 ppm) after 60 min. These findings highlight the potential of synthesizing ZnO nanorods via DH technique as an efficient and sustainable solution for removing pharmaceutical contamination in water sources.

In situ fabrication of Ag nanoparticles modified vertically-grown ZnO nanorods on carbon fiber paper electrode for simultaneous detection of luteolin, daidzein and baicalein

In this paper, a facial strategy is employed to directly growing ZnO nanorods (ZnONR) on carbon fiber paper (CFP) and functionalizing with silver nanoparticles (AgNP), constructing a structural stable paper-based electrode (AgNP/ZnONR@CFP). This unique AgNP/ZnONR hierarchical nanoarchitecture provides large surface area and an easy substrate penetrable structure facilitating enhanced electrochemical features towards flavonoids oxidation. When the electrode is evaluated as a binder-free sensor for flavonoids detection, three distinct and separate differential pulse voltammetric peaks for luteolin, daidzein, and baicalein are observed, demonstrating the simultaneous and selective detection of these flavonoids possible. The AgNP/ZnONR@CFP sensor demonstrates a remarkable wide linear relationship with low detection limits for luteolin, daidzein, and baicalein detection in a mixed solution. When the sensor is employed to analyze luteolin, daidzein, or baicalein in real extracts from Japanese Honeysuckle, Soybean, and Chrysanthemum morifolium, satisfactory recovery rates (ranging from 96.3 % to 102.5 %) and low relative standard deviation (RSD) values (less than 5.0 %) are obtained. In addition, an assembled sensor device (two-electrode) based on this trimmable AgNP/ZnONR@CFP electrode exhibits remarkable quick response and excellent sensitivity for luteolin, daidzein, or baicalein detection, facilitating real-time and portable detection, highlighting its great potential in batch production of the sensor devices.

Enhanced thermal conductivity in vertically grown ZnO Nanorods/ Poly(3,4-ethylenedioxithiophene): Poly(4-styrenesulfonate) composite thin films

Herein, we have investigated the thermal properties of compact and vertically grown ZnO nanorods (NRs)/poly(3,4-ethylenedioxithiophene):poly(4-styrenesulfonate) (PEDOT:PSS) composite film. The ZnO NR arrays with length 885 ± 5 nm have been grown using the sol–gel method. Furthermore, composite films of compact-ZnO and ZnO NR with PEDOT:PSS have also been grown. The temperature-dependent thermal conductivity for both the composite films has been investigated in the temperature range of 273–353 K. The thermal conductivity of compact-ZnO/PEDOT:PSS is found to be in between 1.43–1.49 W/mK. The thermal conductivity is found to be enhanced significantly in the case of ZnO NR/PEDOT:PSS composite film.

Investigations on the microwave-assisted growth of ZnO nanorods and the performance of nanostructured heterojunction UV photodetector

Vertically aligned ZnO nanorods have been grown using the microwave-assisted technique. The current approach offers a potential environment for achieving the ultra-fast (3–7 min) growth of ZnO nanorods compared to the conventional aqueous solution method, where the growth proceeds over a longer time in hours. ZnO nanorods have been grown by altering the molarity, microwave power, and growth time. Increasing the molarity and microwave power resulted in increasing dimensions of the nanorods. The growth of the ZnO nanorods began around 3 min, and it was noticed that the length of the nanorods increased as the growth period progressed. The nanorods grown using this technique have been effectively used to fabricate CuI/ZnO nanorods heterojunction.

Preparation and characterization of ZnO/CuO nanocomposites thin films for highly efficient visible-light photocatalysis of acriflavine dye

Chemical bath deposition (CBD) was used to grow ZnO nanorods on glass substrates. Grown ZnO nanorods are dipped in a copper nitrate trihydrate [Cu(NO3)2.3 H2O] solution at 90 °C for 30 min before being annealed at 400 °C for 1 h to convert Cu2+ ions to CuO nanoparticles, forming a ZnO/CuO thin films nanocomposite. Images obtained from a Field Emission Scanning Electron Microscope (FESEM) indicated that the ZnO structure consisted of nanorods coated in CuO nanoparticles. The optical absorption of both ZnO NRs and ZnO/CuO nanocomposites thin films was strongly edged, with an energy gap of 3.26 and 3.21 eV, respectively. The photodegradation rate of the manufactured ZnO NRs and ZnO/CuO nanocomposites thin films against Acriflavin dye was investigated at room temperature under varying pH conditions and period exposure to visible light. The rate of photodegradation of the dye was increased by increasing the time it was exposed to light and/or the pH of the solution. The photodegradation rates for AFN dye under visible light irradiation ranged from 36% to 100% as the pH value was increased from 4 to 10, and from 78% to 66% at a pH value of 12 and reduced to 78% at a pH value of 12 after 330 min of irradiation. Furthermore, the trapping experiments of reactive species for Acriflavin dye degradation by ZnO/CuO nanocomposites photocatalysts were also carried out

Significantly enhanced piezo-photocatalytic properties of recyclable nanocomposite films by growing ZnO nanorods on inverse opal structured TiO2 framework

The construction of recyclable films with unique morphology and piezoelectric-enhanced photocatalytic performance is of great significance for wastewater purification. Here, inverse opal structured ZnO@TiO2 nanocomposite film were prepared by template method and chemical water bath method. The piezo-photocatalytic properties of the obtained ZnO@TiO2 nanocomposite films were evaluated by the degradation of organic dyes. The results showed that the piezo-photocatalytic constant rate of the ZnO@TiO2 nanocomposite films under the synergistic action of ultrasound and ultraviolet light reached 52.3×10−3 min−1, much higher than those of the pure inverse opal TiO2 framework under same condition (6.6×10−3 min−1) and the ZnO@TiO2 nanocomposite films under only ultraviolet light (10.1×10−3 min−1) or only ultrasound (2.0×10−3 min−1). It is believed that the inverse opal structured TiO2 framework not only provides an open space for ZnO nanorods growth, but also initiates redox reaction for dye degradation through generation and transfer of photo-generated carriers under ultraviolet irradiation. Meanwhile, the ZnO nanorods can efficiently promote carrier separation by piezoelectric polarization electric field and interface contact induced band tilting with TiO2, thus significantly improving the piezo-photocatalytic activity. This work provides a novel route for reasonable design of recyclable and efficient piezo-photocatalytic films.

Effect of Deposition Time on Material Properties of ZnO Nanorods Grown on GZO Seed Layer by CBD

ZnO nanorods (ZNRs) were grown on Ga-doped ZnO (GZO) through a two-step procedure, involving pre-treatment to form the seed layer followed by growth of the nanorods through chemical bath deposition (CBD) method

Using a protrusion sapphire substrate to synthesize ZnO nanoflower arrays and application of Cu decorated ZnO nanoflower arrays as a H2 and CO gas sensor

In this study, a straightforward method is proposed to grow ZnO nanoflower arrays, which will be utilized as gas sensors for detecting H2 and CO gases. The process involves using the sol–gel method to create the ZnO thin films on a sapphire substrate with protrusion structure. These thin films are then annealed to serve as the seed layer for the subsequent growth of ZnO nanorods. For the synthesis of the ZnO nanorods, a 0.3[Formula: see text]M solution containing C6H12N4 and Zn(CH3COO)2 − 2H2O was employed as the precursor, and the hydrothermal method was used at 90∘C for a synthesis time of 60[Formula: see text]min. Due to the unique protrusion structure of the ZnO seed layer, the ZnO nanorods grew perpendicular to it, resulting in the formation of the ZnO nanoflowers. Furthermore, the ZnO seed layer’s matrix structure enables the growth of the ZnO nanoflowers in an orderly array pattern. For the further enhancement of the sensing properties of the gas sensor, a deposition method was used to decorate the Cu nanomaterials on the ZnO nanoflower arrays. The undecorated and Cu-decorated ZnO nanoflower arrays were proceeded to fabricate devices utilizing complemented by an interdigital upper electrode. Subsequently, the gas-sensing performance of both sensor types was compared concerning their ability to detect H2 and CO gases. The findings in this research conclusively indicate that sensors fabricated using the Cu-decorated ZnO nanoflower arrays exhibited a remarkable enhancement in gas-sensing properties when compared to the device using the undecorated ZnO nanoflower arrays, particularly for detecting H2 and CO gases. These results demonstrated that the Cu-decorated sensors had substantially higher response rates and faster response times during the gas-detecting processes.

3D Printing Architecting β-PVDF Reservoirs for Preferential ZnO Epitaxial Growth Toward Advanced Piezoelectric Energy Harvesting.

For polyvinylidene fluoride (PVDF) based piezoelectric composites, epitaxial growth of ZnO nanorods (ZnO-nr) piezoceramic layer on PVDF is an effective way to improve their piezoelectric performance. However, the crystal nucleus of ZnO featuring polar surfaces that cannot be directly attached to hydrophobic PVDF with low surface energy. Herein, direct ink writing (DIW) 3D printing is employed for the first time to create β-PVDF reservoirs with significantly enhanced surface energy, facilitating the attachment and epitaxial growth of ZnO-nr. The printed β-PVDF reservoirs designed with programmed macro-pores and abundant inner micropores, enable a higher loading of ZnO-nr by more than one magnitude, thereby boosting the electro-mechanical response. The resulting PVDF/ZnO core-shell piezoelectric energy harvester (PEH) delivers an output voltage of 33.2V, as well as an unprecedentedly high relative output voltage of 2.76V/wt.%, which is 2.63 times that of the state-of-the-art 3D-printed PVDF/piezoceramics PEHs. Furthermore, it can differentiate subtle human motions whereas hybrid PEHs cannot distinct. This work demonstrates that the DIW 3D printing approach offers a simple and convenient design idea for creating high performance PEHs.

Gold Nanoparticle Sensitized Zinc Oxide Nanorods-Based Nitric Oxide Gas Sensors with High Sensitivity, Selectivity and Low Detection Limit

Development of a low-cost hand-held nitric oxide (NO) sensor with high selectivity, sensitivity and low detection limit is attractive for environment and health monitoring applications. NO gas sensor was fabricated using hydrothermally grown ZnO nanorods (ZnO NRs). The sensing performance like sensor response, sensitivity, detection limit has been improved significantly by attaching gold nanoparticles (Au NPs) with ZnO NRs. Au NPs were synthesized by chemical reduction method from gold chloride trihydrate. The attachment of Au NPs on nanorods was done by spin coating method. The maximum sensor response and sensitivity were obtained at [Formula: see text]C operating temperature with [Formula: see text]l gold loading. The interference study of the sensor was carried out with acetone, ammonia, carbon monoxide, hydrogen peroxide and propanol. It demonstrated high selectivity towards the interfering gases and high humid condition. Au-decorated ZnO NRs exhibited very low detection limit [Formula: see text][Formula: see text]ppb, which is attractive for biomedical applications.

Hydrothermally grown ZnO nanorods in different aspect ratios and their gas sensing properties

On a glass substrate, zinc oxide nanorods (ZnO NRs) arrays of varying aspect ratios have been grown by hydrothermal method at 90 ᴼC with variable ZnO seed layer thicknesses applied by RF sputtering. The structural properties and gas sensitivity of zinc oxide nanorods were studied by using X-ray diffraction (XRD) for analyzing the structural characteristics was discovered that ZnO NRs and seed layer films are both polycrystalline, with the same plane preferred reflection for (002). The seed layer's crystallite size ranges from 19.51 nm to 30.45 nm for thicknesses t1 and t4, respectively. The measurements of the FESEM showed aspect ratios for ZnO NRs ranging from 3.03 for t1 to 4.9 for t4, with growth in different shapes: ZnO NRs for t1, flowers and rod-like shapes for thicknesses t2 and t3, and hexagonal-rod-like shapes for t4. ZnO NRs based on gas sensors and tests of the response of prepared samples on NH3 and CO2 gases showed good sensitivity to both gases at different concentrations (1000, 2000, and 3000 ppm), reaching 65–70 at operating 50 ᴼC.

Construction of hierarchical ZnO-NiCo2O4-NiCo2O4 core-shell microstructure with efficient microwave absorption

Core-shell structural design is an attractive strategy to achieve high-performance microwave absorbers. Nevertheless, it still remains a problem to simultaneously obtain superior microwave dissipation and impedance matching for microwave absorption (MA) materials. In this work, ZnO-NiCo2O4-NiCo2O4 (ZNN) core–shell microstructure is designed and fabricated by covering NiCo2O4 nanosheets on the surface of ZnO nanorod and next growth of NiCo2O4 nanoparticles. With the synergies from the NiCo2O4 nanosheets improving the microwave attenuation capability and the NiCo2O4 nanoparticles increasing the impedance matching, ZNN possesses efficient MA performance: the strongest reflection loss is −59.93 dB at the corresponding thickness of 2.6 mm, and the maximum absorption bandwidth is 7.04 GHz at 2.4 mm, which covers the entire Ku-band. RCS simulation also indicates that ZNN has outstanding MA performance. Moreover, this study proposes a point for the utilization of nickel–cobalt oxides in MA materials, and offers a reference for the design of core–shell structural absorbers.