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This paper aims to study the sensitivity enhancement effect of the gold nanorod on fiber surface plasmon resonance (SPR) sensor. It proposes modeling the sensing effects of fiber SPR sensor decorated with metal nanoparticles. By using simulation and experiment, the sensitivity enhancement effect of the gold nanorod was studied and demonstrated.

The paper opted for an exploratory study using simulation approach of finite-difference time-domain. Specifically, the effect of ratios and aspect ratios of gold nanorod on sensing performance are investigated theoretically. Based on the mathematical models, the validation experiments by using the gold nanorod with the aspect ratios of 5.1 were done to verify the sensitivity enhancement effect of the gold nanorod.

In conclusion, it is evident that with the increases of the aspect ratios, the sensing sensitivity of the refractive index increases first, then gradually stabilizes or decreases. After parameter optimization, the ratios and aspect ratios of gold nanorod are chosen to be 8 nm and 12.5, respectively, which makes the optimal refractive index sensitivity of 4465.53 nm/RIU be realized. In addition, the validation experiments by using the gold nanorod with the aspect ratios of 5.1 verify the sensitivity enhancement effect of the gold nanorods.

This paper proposes and demonstrates a new method for the sensitivity enhancement of fiber SPR sensor. After parameter optimization, the maximum sensitivity of 4465.53 nm/RIU was achieved by using 8 nm gold nanorods with the aspect ratios of 12.5. To verify the sensitivity enhancement of the gold nanorods, the authors also did the validation experiments. The testing results indicated that after the decoration of the gold nanorods, the sensitivity of the sensing probe increases from 2190.57 nm/RIU to 2693.24 nm/RIU, which demonstrates the sensitivity enhancement effect of the gold nanorods.

The purpose of the current research is to use impedance spectroscopy to study the AC parameters that varied with frequency such as impedance, dielectric constant and conductivity of ZnO nanorods MSM structure in the range of 1 Hz to 10 MHz under atmospheric conditions.

ZnO nanorods were grown on glass substrate using low cost sol‐gel method. 0.35 M seed solution was prepared by dissolving zinc acetate dihydrate in 2‐methoxyethanol and monoethanolamine which acts as a stabilizer was added drop‐wise. Prior to the deposition, glass slide was cut into pieces of 1.5 cm×2 cm. Ultra‐sonication process is used to clean the glass substrate using acetone, ethanol, and de‐ionized (DI) water for 5 min. The prepared seed solution was coated on glass substrate using spin coater at spinning speed of 3000 rpm for 30 s and then dried at 250°C for 10 min followed by annealing at 550°C for 2 h. The hydrothermal growth was carried out in aqueous solution of zinc nitrate hexahydrate (25 mM), hexamethyltetramine (25 mM).

ZnO nanorods were characterized using scanning electron microscope (SEM), X‐ray diffraction (XRD) and impedance spectroscopy. The real part of impedance (Z′) showed two semicircles that correspond to the distribution of the grain boundaries and electrode process. SEM image showed the densely packed ZnO nanorods on the surface of glass substrate, whereas XRD revealed the grown nanorods have c‐axis orientation. The results show that the impedance dielectric increases as the frequency decreases while the conductivity showed the opposite behavior.

This paper demonstrates the electron transport mechanism of ZnO nanorods at room temperature to understand the frequency dependent parameters.

The purpose of this paper is to investigate the electrical transport mechanism of the Al‐doped ZnO nanorods at different temperatures by employing impedance spectroscopy.

Al‐doped ZnO nanorods were grown on silicon substrate using step sol‐gel method. For the seed solution preparation Zinc acetate dihydrate, 2‐methoxyethanol, monoethanolamine and aluminum nitrite nano‐hydrate were used as a solute, solvent, stabilizer and dopant, respectively. Prior to the deposition, P‐type Si (100) wafer was cut into pieces of 1 cm×2 cm. The samples were then cleaned in an ultrasonic bath with acetone, ethanol, and de‐ionized (DI) water for 5 min. The prepared seed solution was coated on silicon substrate using spin coater at spinning speed of 3000 rpm for 30 s and then dried at 250°C for 10 min followed by annealing at 550°C for 1 h. The hydrothermal growth was carried out in a solution of zinc nitrate hexahydrate (0.025M), Hexamethyltetramine (0.025M) in DI water.

Al‐doped ZnO nanorods were characterized using scanning electron microscope (SEM), X‐ray diffraction (XRD) and impedance spectroscopy. The impedance measurements were carried out at various temperatures (100°C‐325°C). The impedance results showed that temperature has great influence on the impedance; the impedance value decreased as the temperature increased. This decrement is attributed to the increase of the mobility of the defects, especially the oxygen vacancies. The surface morphology of the samples was measured by SEM and X‐ray diffraction. The SEM images show that the high density of Al‐doped ZnO nanorods covers the silicon substrate, whereas the XRD pattern shows the (002) crystal orientation.

This paper demonstrates the electron transport mechanism of Al‐doped ZnO nanorods, at different temperatures, to understand the charge transport model.

The purpose of this study was to investigate the performance of a single-bridge ZnO nanorod as a photodetector.

The fabrication of the design sensor with ∼6-μm gap Schottky contacts and bridging of the ZnO nanorod were based on conventional photolithography and wet-etching technique. Prior to bridging, the ZnO nanorods were grown by the hydrothermal process. The 0.35 M seed solution was prepared by dissolving zinc acetate dihydrate in 2-methoxyethanol, and monoethanolamine, which acts as a stabilizer, was added drop-wise. Before starting the solution deposition, and oxide, titanium (Ti) and gold (Au) layer deposition, p-type (100) silicon substrate was cleaned with Radio Corporation of America (RCA1) and RCA2, followed by dipping in diluted hydrofluoric acid. The aged solution was dropped onto the surface of the Au microgap structure, using a spin coater at a spinning speed of 3,000 rpm for 45 seconds, and then dried at 300°C for 15 minutes, followed by annealing at 400°C for 1 hour. The hydrothermal growth was carried out in an aqueous solution of zinc nitrate hexahydrate (0.025 M) and hexamethyltetramine (0.025 M).

In this study, ZnO nanorods were grown on a SiO₂ substrate by the hydrothermal method. Microgap electrodes with ∼6-μm spacing were achieved by using the wet-etching process. After the growth process, an area-selective mask was utilized to reduce the number of rods between the nearby gap areas. The obtained single ZnO nanorod was tested for the UV-sensing application. The single ZnO nanorod photodetector exhibited a UV photoresponse, thereby indicating potential as a cost-effective UV detector. The response and recovery times of the fabricated device were 65 and 95 seconds, respectively. Structural analysis was captured using X-ray Diffraction (XRD), whereas surface morphology was determined using scanning electron microscopy.

This paper demonstrates the effect of UV photon on a single-bridge ZnO nanorod between microgap electrodes.

The purpose of this study is to fabricate an ultraviolet (UV) metal-semiconductor-metal (MSM) photodetector based on zinc oxide nanorods (ZnO NRs) grown on seeded silicon (Si) substrate that was prepared by a low-cost method (drop-casting technique).

The drop-casting method was used for the seed layer deposition, the hydrothermal method was used for the growth of ZnO NRs and subsequent fabrication of UV MSM photodetector was done using the direct current sputtering technique. The performance of the fabricated MSM devices was investigated by current–voltage (I–V) measurements. The photodetection mechanism of the fabricated device was discussed.

Semi-vertically high-density ZnO (NRs) were effectively produced with a preferential orientation along the (002) direction, and increased crystallinity is confirmed by X-ray diffraction analysis. Photoluminescence results show a high UV region. The fabricated MSM UV photodetector showed that the ZnO (NRs) MSM device has great stability over time, high photocurrent, good sensitivity and high responsivity under 365 nm wavelength illumination and 0 V, 1 V, 2 V and 3 V applied bias. The responsivity and sensitivity for the fabricated ZnO NRs UV photodetector are 0.015 A W-1, 0.383 A W-1, 1.290 A W-1 and 1.982 A W-1 and 15,030, 42.639, 100.173 and 334.029, respectively, under UV light (365 nm) illumination at (0 V, 1 V, 2 V and 3 V).

This paper uses the drop-casting technique and the hydrothermal method as simple and low-cost methods to fabricate and improve the ZnO NRs photodetector.

Growth of nickel tip carbon nanorod by means of pulsed plasma chemical vapor deposition (PPCVD) was carried out at different deposition time. Effects of deposition time under the methane plasma on the growth of carbon nanorod were investigated. The nucleation and growth mechanism of nickel tip carbon nanorod were also discussed. Nanoparticles were formed on substrate to introduce more nucleation sites at an elevated deposition time, and the density of nanorod on the surface of the substrate was greatly increased until the proper methane plasma deposition time. The longest nanorods and the highest nanorods density were found after methane plasma treatment of 3 min and 10 min respectively. Nanorod was about 60 nanometers in diameter and about 550 nanometers in length. Nanorods had onion and V-shape with Ni tip.

The aim of this paper is to synthesize graphene-modified titanium dioxide (GR-TiO₂) nanorod arrays nanocomposite films, so that these can enhance the photocatalytic properties of titanium dioxide and overcome the problem of difficult separation and recovery of photocatalysts.

The GR-TiO₂ nanocomposite films were synthesized via hydrothermal method and spin-coating. The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), ultraviolet–visible (UV-Vis) diffuse reflectance spectrum and Raman spectrum. The photocatalytic performance of the GR-TiO₂ nanocomposite films for degrading Rhodamin B under ultraviolet (UV) was studied by a UV-Vis spectrophotometer. The photocatalytic enhancement mechanism of graphene was studied by photoelectrochemical analysis.

The introduction of graphene expanded the range of the optical response of TiO₂ nanorod arrays, improving the separation efficiency of the photogenerated electron-hole pairs, and thus dramatically increasing its photocatalytic performance.

A simple and novel way for synthesizing GR-TiO₂ nanocomposite films has enhanced the photocatalytic performance of TiO₂.

The photocatalyst synthesized is easy to separate and recycle in the process of photocatalytic reaction, so it is possible to achieve industrialization.

The purpose of this paper is to demonstrate the n‐ZnO/p‐Si Schottky photodiodes.

A Zn film was deposited on silicon substrate by dc sputtering deposition technology from high purity zinc (Zn) targets. Then, the Zn films were then annealed under flowing oxygen (O₂) gas environment in the furnace. ZnO nanorods morphologies have been successfully prepared through a simple method. No catalyst is required.

The structures and morphologies of the products were characterized in detail by using X‐ray diffraction, energy dispersive X‐ray, and scanning electron microscopy (SEM). According to experimental results, the current‐voltage characteristics of the device show the typical rectifying behaviour of Schottky diodes. The UV photocurrent measurement was performed using an UV lamp under a reverse bias.

The paper demonstrates that the n‐ZnO/p‐Si diodes exhibit strong rectifying conduct described by the current‐voltage (I‐V) measurement under a dark and illumination conditions.

Over the past decades, intense efforts have been devoted to design and synthesize efficient photocatalysts which are active under sunlight for environmental and energy applications. Titanium dioxide (TiO₂) has attracted much attention over many years for organic contaminant degradation in air or water due to its strong optical absorptivity, chemical stability and low cost. However, TiO₂ has a very low photo quantum yield which prompts the easy recombination of photogeneration electron/hole pairs. In addition, bandgap of 3.2 eV restrains application of this photocatalyst mainly to the UV range.

Vertically oriented one-dimensional TiO₂ nanostructures remarkably improve electron transport by creating a direct conduction pathway, decreasing intercrystalline contacts and stretching grown structure with the specified directionality. In this research, to enhance the visible light absorbance of TiO₂, prearranged hydrogenated titanium dioxide nanorods (H-TNRs) in the presence of H₂/N₂ gas flow are hydrothermally synthesized.

The X-ray diffraction patterns illustrated the characteristic peaks of tetragonal rutile TiO₂ and confirmed that there is no phase change after hydrogenation. Trivalent titanium ions surface defects and oxygen vacancies were considered as major reasons for redshift of absorption edge toward visible region and subsequently narrowing the bandgap to 2.27 eV. The optimized photocatalysts exhibited high visible-light-driven photocatalytic activity for degradation of methylene blue in water within 210. The synthesized H-TNRs established themselves as promising photocatalysts for organic compounds degradation in the aqueous solution.

To the best of the authors’ knowledge, this work is original and has not been published elsewhere nor is it currently under consideration for publication elsewhere.

Indium tin oxide (ITO) thin film as a gas sensor has a good stability and performance. The purpose of this paper is to compare the effect of depositing different metal layers in various structures on the gas sensing properties of ITO toward ethanol and carbon dioxide.

In this work, the authors have investigated the effect of depositing an ITO layer by Electron Beam Evaporation technique under, on top and in the middle of the metal layers. Surface morphology and the response of the fabricated sensors were compared and the changes in the response of the sensors to ethanol and carbon dioxide gases were studied at various gas concentrations and operating temperatures. The sensing mechanism and result of the other studies were also discussed.

Comparing various sensor structures reported in this study showed that the ITO nanorods which grow over distinct Ag nano-islands in the ITO/Ag structure has the highest response of 420 per cent to ethanol which is 6 times more than the single-layer ITO sensor. Further, gold nanoparticles on ITO nanorods in Au/ITO/Ag structure produce a very complex structure that exhibits the best response of 150 per cent to carbon dioxide which is 6.5 times more than the single-layer ITO sensor. The response and the recovery times were improved also.

Different ITO-metal gas sensor structures were studied and compared toward ethanol and carbon dioxide. Response enhancement and various surface changes through a series of experiments and analysis were discussed and compared to the literature.