Liquid Phase Deposition Method Research Articles

Synthesis and photoluminescence properties of the ZnO@SnO2 core–shell nanorod arrays

The ZnO@SnO2 core–shell nanorod arrays have been synthesized. As the cores, ZnO nanorod arrays were first prepared by aqueous chemical growth method. Then using a simple liquid-phase deposition method, SnO2 was deposited on the ZnO nanorod arrays. Scanning electron microscopy, transmission electron microscopy, and X-ray diffraction were used to characterize the morphologies and structures of the products. Photoluminescence properties were also investigated. It was found that the ZnO@SnO2 core–shell nanorod arrays showed enhanced UV and green emissions when compared with the bare ZnO nanorod arrays.

Low-Temperature Synthesis and Gas Sensing Properties of Anatase TiO<sub>2</sub> Thin Films

Crystalline anatase TiO2thin films were obtained on glass substrates at 60°C, 75°C and 90°C, respectively, by liquid phase deposition (LPD) method without subsequent heat treatment. X-ray diffraction (XRD), atomic force microscopy (AFM) and UV-Vis spectrophotometer were used to characterize the as-synthesized TiO2thin films. The H2sensing properties of the TiO2thin films based sensors were investigated. The results show that the gas sensors signal Ra/Rg (Ra: resistance in air, Rg: resistance in a sample gas) decreases with the increasing deposition temperature. The TiO2thin films obtained at deposition temperature of 60°C exhibited the maximum H2gas response at 350°C, and the magnitude of the sensor signal and the response time for 500ppm H2was 1.25 and 17s, respectively.

Fabrication of 3D interconnected porousTiO2 nanotubes templatedby poly(vinyl chloride-g-4-vinyl pyridine) for dye-sensitized solar cells

Porous TiO2 nanotube arrays with three-dimensional (3D) interconnectivity wereprepared using a sol–gel process assisted by poly(vinyl chloride-graft-4-vinylpyridine), PVC-g-P4VP graft copolymer and a ZnO nanorod template. A7 µm long ZnO nanorod array was grown from the fluorine-doped tinoxide (FTO) glass via a liquid phase deposition method. TheTiO2 sol–gel solutiontemplated by the PVC-g-P4VP graft copolymer produced a random 3D interconnection betweenthe adjacent ZnO nanorods during spin coating. Upon etching of ZnO,TiO2 nanotubes consisting of 10–15 nm nanoparticles were generated, as confirmed by wide-anglex-ray scattering (WAXS), energy-filtering transmission electron microscopy (EF-TEM) andfield-emission scanning electron microscopy (FE-SEM). The ordered and interconnectednanotube architecture showed an enhanced light scattering effect and increased penetrationof polymer electrolytes in dye-sensitized solar cells (DSSC). The energy conversionefficiency reached 1.82% for liquid electrolyte, and 1.46% for low molecular weight(Mw) and 0.74%for high Mw polymer electrolytes.

The Preparation of a Novel Composite Film Based on Polyoxometalate for Visible Light Photocatalysis

The composite film, FeW11O399-(FeW11)/TiO2/ SiO2, was prepared by liquid phase deposition method (LPD) at low processing temperature for the first time. Formation of the stable composite film is due to strong chemical reaction of ≡Ti-OH from TiO2/SiO2 with the surface oxygen atoms at vacant sites of FeW11. The structural properties of the film were characterized using FT-IR、UV-vis spectra, Elemental Analysis. The experimental results confirmed the retention of the primary Keggin structure and the saturation of the surface of the lacunary FeW11; Formation of Ti–O–Si bond implies that the TiO2 crystallites highly dispersed on the silica surface via oxygen as a bridge. The catalytic activity was tested by the photo-degradation of aqueous azo dye congo red (CR) (0-20 mmol•L-1). The resulting film exhibited efficient visible-light photocatalytic activity to decompose aqueous azo dye CR，which is mainly attributed to long time existence of Fenton-assisted FeW11/TiO2/SiO2 excitation state. According to the experimental results, a synergistic effect mechanism of the photodegradation process is proposed.

Gas-Sensitive Behavior Based on Charge Transfer Processes of a Novel Polyoxometalate (POM)/TiO<sub>2</sub>/SiO<sub>2</sub> Composite Film

The POM/TiO2/SiO2 Supermolecule composite based on POM films were synthesized via an easy liquid phase deposition method (LPD) at low processing temperature for the first time and employed for studying the charge transfer processes between the film and ambient atmospheres. Here the POM is the Keggin type lacunary FeW11O399- (FeW11) polyanion. Gaseous adsorption properties of the films to noxious gases such as NH3 show that the composite is much better than that of the TiO2/SiO2 films, which may be attributed to the enhancement of the gaseous adsorption ability on the film surface as well as the modified charge transfer process between the adsorbed gases and the films due to the inducing of POM into TiO2/SiO2 matrix. In addition, more importantly, compared with the TiO2/SiO2 films, the POM/TiO2/SiO2 films showed relative faster response and recovery time at optimal working temperature of 440 K, indicating that the films have great potential to be designed as gas sensor used at low temperature.

<i>In Situ</i> Template Synthesis Titania Nanotube Array Films on Aluminum Plate

Titanium dioxide nanotube array films on aluminum plate were prepared via liquid phase deposition (LPD) method. The samples were characterized by field-emission scanning electron microscopy (FE-SEM) with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR). The results show that the nanotube array films’ morphology depends on the anodic aluminum oxide (AAO) structure and deposition time. The titanium dioxide nanotube’s outside diameter is about 250 nm, the wall thickness is approximately 40 nm. The as-prepared TiO2array films are amorphous and anatase appeared after calcining at 400°C for 2 hrs. FT-IR spectrum indicates that there are lots of hydroxyl groups on the surface of AAO. When AAO was immersed into 0.1 M (NH4)2TiF6solution at room temperature, AAO was dissolved in the solution and the holes became wide. The hydrolysis reaction was shifted to the right-hand side, TiO2particles locked in-situ on the inner surface of the anodic alumina pore induced by hydroxyl group, thus nanotube array film was obtained.

Application of liquid phase deposition method for preparation of Co/ZrO x/SiO 2 catalyst with enhanced Fischer–Tropsch synthesis activity: Importance of Co–Zr interaction

Liquid phase deposition (LPD) method using (NH 4) 2ZrO(CO 3) 2 was applied to modifying chemical nature of SiO 2 surface with ZrO x species. ZrO x -modified SiO 2 was then impregnated with Co nitrate solution for preparation of Co/ZrO x /SiO 2 catalysts with 5 and 20 mass% Co loadings. Modification of SiO 2 surface with ZrO x using the LPD method enhanced FTS activity of the Co/ZrO x /SiO 2 catalysts under the reaction conditions of 503 K and 1.1 MPa. The LPD method was superior to other method reported previously such as impregnation and sol–gel methods in terms of surface modification of SiO 2 with ZrO x . H 2-TPR, XRD and hydrogen chemisorption measurements revealed that modification of SiO 2 surface with ZrO x using the LPD method enhanced dispersion of Co 0 without loss of high reducibility of Co. However, degree of Co 0 dispersion was less than that expected from enhancement of activity for the catalysts induced by ZrO x modification, indicating that turnover frequency (TOF) increased in the presence of ZrO x . This effect was particularly important for the catalyst with the low Co loading. Furthermore, in situ DRIFT measurement provided evidence for the formation of specific interaction of Co species with Si–OH and Zr–OH species in the Co/ZrO x /SiO 2 catalysts. It was suggested that the formation of such specific interaction was responsible for not only enhancement of Co 0 dispersion but also increase in TOF of the ZrO x modified catalysts.

Textured zinc oxide prepared by liquid phase deposition (LPD) method and its application in improvement of extraction efficiency for 650 nm resonant-cavity light-emitting diode (RCLED)

In this article, we report on the textured zinc oxide (ZnO) prepared by liquid-phase deposition (LPD) method and apply it as a window layer of 650 nm resonant-cavity light-emitting diode to enhance the extraction efficiency. The treatment solution for LPD ZnO (LPD-ZnO) growth consists of ZnO powder saturated with hydrochloric acid (HCl) and hydrogen peroxide (H 2O 2). Temperature-controlled water bath system was used to maintain a constant temperature of 40 °C in LPD system. The experimental results indicate that the deposition rate was determined by the concentration of H 2O 2 and growth temperature, and the average roughness of LPD-ZnO is dominated by the concentrations of HCl. In order to perform the practicability of LPD-ZnO, the textured LPD-ZnO is used as a window layer of 650 nm AlGaInP/GaInP resonant-cavity light-emitting diode (RCLED) to enhance the light output power. In addition, the calculated results indicate that the optimum roughness for enhancing the light output power of RCLED is in the range of 80–100 nm, which are close to the experimental results. As compared to the conventional RCLED, the RCLED with textured LPD-ZnO, which has the optimum average roughness of 82 nm, performs a high light output power, a high external quantum efficiency, a narrow linewidth of electroluminescence spectrum and the same far-field angle.

Antibacterial Property of Chinese fir/TiO<sub>2</sub> Composite

Small samples of Chinese fir/TiO2 Composite were prepared using sol-gel method and microwave assisted liquid phase deposition (MWLPD) method for the first time. Results of antibacterial test show that during a one year test the samples exhibited prominent, broad-spectrum and long-lasting antibacterial performance, but were also influenced by light exposure and temperature.

Fabrication and photocatalytic activity of TiO2/SiO2 composite nanotubes

TiO2/SiO2 composite nanotube photocatalysts supported on Al substrates were prepared by the anodic aluminum oxide (AAO) liquid-phase deposition method for degradation of 100 mg/L methyl blue (MB). AAO templates were prepared in H3PO4 acidic electrolytes through the two-step anodic oxidation method. The photocatalysts were characterized by field-emission scanning electron microscopy, thermal analysis (TG-DTA), and Fourier-transform infrared, x-ray photoelectron, and UV–Vis diffuse spectroscopies. The results showed that the presence of SiO2 in TiO2 inhibited the crystal phase transformation temperature effectively, with a greater wall thickness of 80–100 nm. It was found that Ti–O–Si bonds were formed on the surface and the surface hydroxyl concentration was increased, resulting in enhanced photocatalytic activity, being about 20% higher than for pure TiO2 films. The calculated band structure for TiO2/SiO2 was investigated using first-principle calculations. The TiO2/SiO2 composite exhibited a wider conduction band which would effectively prohibit recombination of photogenerated electrons and holes.

A novel two-step method to synthesize lotus-leaf-structured TiO 2 nanocrystals with good photocatalytic activity

Lotus-leaf-structured TiO 2 nanocrystals were prepared by a novel simple two-step method. TiO 2 nanocrystals obtained by two-step method exhibited better photocatalytic activity than the as-prepared TiO 2 nanocrystal obtained by one-step liquid phase deposition method. Even compared with commercial TiO 2 photocatalyst with the smaller average size (~ 7 nm), lotus-leaf-structured TiO 2 nanocrystals exhibited better photocatalytic activity. The possible reason for the good photocatalytic activity was also investigated.

Highly ordered transition metal ferrite nanotube arrays synthesized by template-assisted liquid phase deposition

Highly ordered spinel ferrite MxFe3−xO4 (M = Ni, Co, Zn) nanotube arrays were synthesized in anodic aluminium oxide (AAO) templates with a pore size of 200 nm by combining a liquid phase deposition (LPD) method with a template-assisted route. The morphology of the transition metal ferrite nanotubes was characterized by electron microscopy (FE-SEM; TEM, SAED and HRTEM) and atomic force microscopy (AFM), whereas their chemical composition was determined by inductive coupling plasma (ICP). The phase purity was studied by X-ray diffraction (XRD) and the magnetic properties of the nanotubes were measured by SQUID measurements. Unlike the deposition of thin film structures, nanotube arrays form within the pores of the AAO templates in a much shorter time due to the attractive interactions between the positively charged AAO and the negatively charged metal complex species formed in the treatment solution. The as-deposited nanotubes are amorphous in nature and can be converted into polycrystalline metal ferrites via a post-synthesis heat treatment which induce the dehydroxylation, crystallization and formation of the spinel structure. The resulting nanotubes are uniform with smooth surfaces and open ends and their wall thickness can be varied from 4 to 26 nm by increasing the deposition time from 1 to 4 h. Significant differences in the magnetic properties of the ferrite nanotubes have been observed and these differences seem to result from the chemical composition, the wall thickness and the annealing temperature of the spinel ferrite nanotubes.

Effect of N2-annealing on n-type Si metal–oxide–semiconductor capacitors by using liquid-phase deposition SiO2

Low-temperature silicon-oxide films were grown on n-type Si surfaces using the liquid-phase deposition (LPD) method. Various temperature annealing was employed to improve the electrical properties of LPD-oxide. Metal–oxide–semiconductor (MOS) capacitors were fabricated to characterise the annealing effects on the n-type Si/LPD-oxide interface using current–voltage and capacitance–voltage measurements. Observations showed that the MOS capacitor with as-grown LPD-oxide has a large leakage current density of 2.1×10−5 A/cm2 and fixed oxide charge density of 2.8×1012 cm−2. After 500°C annealing in N2 environment for 30 min, the leakage current density and fixed oxide charge density are drastically reduced to 3.2×10−8 A/cm2 and 1.2×1012 cm−2, respectively.

A facile one-step synthesis of TiO2/graphene composites for photodegradation of methyl orange

TiO2/graphene composite photocatalysts have been prepared by a simple liquid phase deposition method using titanium tetrafluoride and electron beam (EB) irradiation-pretreated graphene as the raw materials. The products were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The effects of varying the synthesis parameters such as graphene content, concentration of titanium tetrafluoride solution and irradiation dose were investigated. It was found that the preparation conditions had a significant effect on the structure and properties of the final products. The irradiated graphene was covered with petal-like anatase TiO2 nanoparticles, which were more uniform and smaller in size than those in products synthesized without EB irradiation-pretreated graphene. The photocatalytic activities of the products were evaluated using the photocatalytic degradation of methyl orange as a probe reaction. The results showed that the products synthesized using EB irradiation-pretreated graphene exhibited higher photocatalytic activities than those using graphene without EB irradiation pretreatment.

Preparation N–F-codoped TiO2 nanorod array by liquid phase deposition as visible light photocatalyst

Abstract An efficient method for the preparation of N–F-codoped visible light active TiO2 nanorod arrays is reported. In the process, simultaneous nitrogen and fluorine doped TiO2 nanorod arrays on the glass substrates were achieved by liquid phase deposition method using ZnO nanorod arrays as templates with different calcination temperature. The as-prepared samples were characterized by Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and UV–vis absorption spectra measurements. It was found that calcination temperature is an important factor influencing the microstructure and the amount of N and F in TiO2 nanorod arrays samples. The visible light photocatalytic properties were investigated using methylene blue (MB) dye as a model system. The results showed that N–F-codoped TiO2 nanorod arrays sample calcined at 450 °C demonstrated the best visible light activity in all samples, much higher than that of TiO2 nanoparticles and P25 particles films.

Photo-degradation of methylene blue by multi-walled carbon nanotubes/TiO2 composites

Multi-walled carbon nanotubes (MWCNTs) and titanium dioxide nanocomposites (MWCNTs/TiO2) were prepared by a liquid phase deposition method and used as a photocatalyst for degradation of methylene blue (MB) in water under light irradiation. The morphology and microstructure of composites were characterized by SEM, TEM, and XRD. It was found that the photo-degradation rate of MB under UV or visible light irradiation depended strongly on the special structure of supported catalyst, pH and electron acceptor (H2O2 used in this study). Those results showed that the MWCNTs/TiO2 composites may be used to adjust the degradation property and may extend potential applications for degradation of organic pollutants.

Magnetoelectric Perovskite-Spinel Bilayered Nanocomposites Synthesized by Liquid-Phase Deposition

Highly uniform bilayered perovskite-spinel hybrid nanostructures were deposited on glass and LaNiO3-buffered (100) silicon substrates at almost-ambient temperatures via the liquid-phase deposition (LPD) method. Field-emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM) evidenced that the perovskite and spinel layers are constructed by arrays of densely packed nanoparticles with uniform sizes. The bilayered nanocomposites exhibit both piezoelectricity and ferrimagnetism at room temperature. The value of the static piezoelectric coefficient of the PbTiO3 (PTO) film was 14.1 pm/V, whereas the values of the saturation magnetization were 234.4 and 223.2 emu/cm3 for the PbTiO3−Co0.32Fe2.68O4 (CFO) and PbTiO3−Ni0.66Fe2.34O4 (NFO), respectively. The coercivity of the nanocomposite decreased by 12.11% for the PTO−CFO, whereas, for the PTO−NFO, it increased by 20%, with respect to the coercivity values of the pristine ferrite films, which is the result of a magnetoelectric coupling betwe...

Preparation of thick GeO 2 glass film with high UV photosensitivity

Hexagonal GeO 2 ceramic films were fabricated at room temperature via an acid induced liquid phase deposition (LPD) method. Thick GeO 2 glass films were prepared using a melting and quick cooling technique. The glass films were annealed in a mixed hydrogen/nitrogen gas atmosphere to create more oxygen vacancies. The intensity of 5-eV absorption band enhances with increase of annealing temperature as well as time. The activation energy of oxygen vacancy formation is calculated to be 0.91 ± 0.05 eV. The 5-eV absorption band is photobleachable, and the saturated absorptivity change reaches 575 ± 17 cm − 1 .

Electrical properties of metal-oxide-semiconductor capacitors using liquid-phase deposited silicon-dioxide gate dielectric on sulfur-passivated germanium

After depositing silicon-dioxide (SiO 2) on a geranium (Ge) substrate at room temperature using a liquid-phase deposition (LPD) method, fabricated metal-oxide-semiconductor (MOS) capacitors were used to extract the passivating properties of LPD-SiO 2 on the surface. The procedure employed X-ray photoelectron spectroscopy, current–voltage and capacitance–voltage measurements. Our observation shows that (NH 4) 2S treatment completely removes the native oxide (GeO 2) from the Ge surface and passivate surface dangling bond. Hence, the (NH 4) 2S treated MOS capacitor reveals a lower leakage current than an untreated capacitor by one order. Different temperatures (200–400 °C) for annealing were proposed to improve the passivating properties of LPD-SiO 2. With increasing annealing temperature, flat-band voltage shift, fixed oxide-charge density, and interface trap density significantly decrease. Such a result indicates that the LPD-SiO 2 and (NH 4) 2S treatment qualifies as a potential candidate in passivating the Ge substrate.

Deposition and characterization of binary Al 2O 3/SiO 2 coating layers on the surfaces of rutile TiO 2 and the pigmentary properties

Binary Al 2O 3/SiO 2-coated rutile TiO 2 composites were prepared by a liquid-phase deposition method starting from Na 2SiO 3·9H 2O and NaAlO 2. The chemical structure and morphology of binary Al 2O 3/SiO 2 coating layers were investigated by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, TG–DSC, Zeta potential, powder X-ray diffraction, and transmission electron microscopy techniques. Binary Al 2O 3/SiO 2 coating layers both in amorphous phase were formed at TiO 2 surfaces. The silica coating layers were anchored at TiO 2 surfaces via Si–O–Ti bonds and the alumina coating layers were probably anchored at the SiO 2-coated TiO 2 surfaces via Al–O–Si bonds. The formation of continuous and dense binary Al 2O 3/SiO 2 coating layers depended on the pH value of reaction solution and the alumina loading. The binary Al 2O 3/SiO 2-coated TiO 2 composites had a high dispersibility in water. The whiteness and brightness of the binary Al 2O 3/SiO 2-coated TiO 2 composites were higher than those of the naked rutile TiO 2 and the SiO 2-coated TiO 2 samples. The relative light scattering index was found to depend on the composition of coating layers.