Chemical Liquid Deposition Method Research Articles

LLDPE/TiO2 composites with high UV aging resistance and mechanical properties by controlling the alumina coating on TiO2

AbstractFor preparing high performance LLDPE film, the photocatalytic activity and the UV absorption capacity of TiO2 were regulated by the alumina coating content on the surface of TiO2. Alumina‐coated TiO2 was prepared by the chemical liquid deposition method, and characterized by element analysis, TGA, FTIR, and morphology observation. The alumina coating layer had been proven to covalently bind to the surface of TiO2 through AlOTi bonds, which formed a continuous and dense coating layer, followed by forming a loose flocculent coating layer with the increase of alumina content. The alumina coating layer could significantly reduce the formation of carbonyl group on the LLDPE chains, and enhance UV aging resistance of LLDPE by inhibiting the photocatalytic activity of TiO2. Moreover, the dispersion of alumina‐coated TiO2 in the LLDPE matrix was improved. Thus, the transmittance of LLDPE/alumina‐coated TiO2 composites was reduced and the whiteness was improved. Importantly, the continuous and dense alumina coating layer was enough to inhibit the photocatalysis effect of TiO2 on LLDPE. The further increase of alumina coating content reduced the UV absorption capacity of alumina‐coated TiO2 and its compatibility with the LLDPE matrix. Therefore, the best alumina coating content on the surface of TiO2 was 1.46 wt% for preparing high performance LLDPE/TiO2 composites.Highlights Alumina‐coated TiO2 with controllable coating thickness was successfully synthesized. LLDPE/alumina‐coated TiO2 has excellent UV aging resistance and mechanical properties. The photocatalytic activity and UV absorption capacity of TiO2 could be regulated. 1.46 wt% of alumina coating is the best content for high performance LLDPE/TiO2 composites.

Conversion of C8 aromatics over a dual-bed catalyst.

A dual-bed catalyst was prepared for the conversion of C8 aromatics. The upper bed layer consisted of ZSM-5 covered with SiO2, primarily utilized for ethylbenzene dealkylation. By employing tetraethyl orthosilicate (TEOS) as a deposition agent through the chemical liquid deposition (CLD) method, the modified ZSM-5 catalyst exhibited optimal catalytic performance at a TEOS addition of 0.6 g per gram of catalyst. The lower bed layer contained ZSM-39 catalyst, mainly employed for xylene isomerization reaction. ZSM-39 was synthesized using pyrrolidine as the template, and the best catalytic performance was achieved when the OH-/SiO2 molar ratio in the synthesis system was 0.05. The mass ratio between the upper and lower agents was maintained at 1 : 1. Compared to traditional single-bed ZSM-5 catalysts, the dual-bed catalyst demonstrated enhanced activity and selectivity.

Intensified shape selectivity and alkylation reaction for the two-step conversion of methanol aromatization to p-xylene

Two-step conversion of methanol to aromatics via light hydrocarbons can significantly improve the conversion stability compared with direct aromatization of methanol, but it remains a challenge to achieve a high p-xylene (PX) selectivity. Herein, silica coating was firstly used to passivate external acid sites of ZSM-5 catalyst for the aromatization of light hydrocarbons by the chemical liquid deposition method. With the increase of SiO2 deposition, the density of the external acid sites of the catalyst was decreased from 0.1 to 0.03 mmol·g−1, which inhibited the surface secondary reactions and increased the PX/X from 34.6% to 60.0%. In view of the fact that the aromatization process in the second step was partly inhibited as methanol was consumed in advance in the upper methanol-to-light hydrocarbons catalyst layer, part of methanol was directly introduced into the lower aromatization catalyst layer to promote the alkylation process during the aromatization, which decreased the toluene selectivity from 34.5% to 14.3% but increased the xylene selectivity from 40.0% to 55.3%. It was also found that an appropriate external acid density was needed for aromatization catalyst to strengthen the alkylation process and improve the selectivity of xylene under the conditions of methanol introduction.

Improved hydrothermal durability of Cu-SSZ-13 NH3-SCR catalyst by surface Al modification: Affinity and passivation

To improve the hydrothermal durability of Cu-SSZ-13 selective catalytic reduction (SCR) catalyst, a thin Al2O3 modification layer was coated on the external surface of Cu-SSZ-13 by a chemical liquid deposition (CLD) method. The high-temperature SCR activity of the Al-modified Cu-SSZ-13 can be maintained upon 750–800 °C hydrothermal aging, and over-oxidation of NH3 is largely inhibited. Based on H2-TPR and EPR results, it is revealed that CuAl2O4-like species forms upon Al modification and converts further to CuAlO2-like species during aging, while the accumulation of CuO-like species is inhibited. The high affinity of Al-containing species (i.e., Al2O3 and CuAl2O4-like species) with Cu(OH)2 is suggested by DFT calculations, indicating that Cu(OH)2 detached from ion-exchange sites are captured by Al to form CuAlO2-like species instead of CuO-like species. The passivation of detached Cu species by coated Al leads to somewhat weakened low-temperature SCR activity, but successfully preserves the high-temperature SCR performance upon aging, which can be applied to high-temperature SCR scenarios.

Helical carbon nanofibers modified with Fe2O3 as a high performance anode material for lithium-ion batteries.

Helical carbon nanofibers (HCNFs) modified with Fe2O3 (Fe2O3/HCNFs) with a particle size of about 10-20 nm were first introduced for potential use as a novel anode material for lithium-ion batteries (LIBs). Fe2O3/HCNFs were successfully prepared via a chemical liquid deposition (CLPD) method in this study. HCNFs with a special three-dimensional helical structure improve the conductivity and also provide a strong supporting network space for stress and strain during the volume expansion of Fe2O3 nanoparticles. The Fe2O3/HCNF anode still retains its capacity of 816.3 mA h g-1 after 100 cycles at the current density of 200 mA g-1, which is significantly better than those of contrast samples (only 144.2 mA h g-1 for the bare Fe2O3, 241.2 mA h g-1 for HCNFs and 486.4 mA h g-1 for Fe2O3-HCNFs). These superior properties and facile preparation represent the potential of Fe2O3/HCNF anode materials for LIB application.

Facile growth of aluminum oxide thin film by chemical liquid deposition and its application in devices

Abstract Uniform and continuous Al2O3 thin films were prepared by the chemical liquid deposition (CLD) method. The breakdown field strength of the amorphous CLD-Al2O3 film is 1.74 MV/cm, making it could be used as a candidate dielectric film for electronic devices. It was further proposed to use the CLD-Al2O3 film as an electron blocking layer in a triboelectric nanogenerator (TENG) for output performances enhancement. Output voltages and currents of about 200 V and 9 µA were obtained, respectively, which were 2.6 times and 3 times, respectively, higher than TENG device without an Al2O3. A colloidal condensation-based procedure controlled by adjusting the pH value of the solution was proposed to be the mechanism of CLD, which was confirmed by the Tyndall effect observed in the growth liquid. The results indicated that the CLD could serve as a low-cost, room temperature, nontoxic and facile new method for the growth of functional thin films for semiconductor device applications.

Effects of silylation on Ga/HZSM-5 for improved propane dehydroaromatization

Dehydroaromatization of propane to high value-added aromatics, especially benzene, toluene and xylene (BTX), has attracted widespread attention. Many works have been done to improve the catalytic performance of gallium loaded HZSM-5 catalysts. However, there were few reports focused on reducing the cracked by-products, such as methane and ethylene, derived from propane cracking reaction on external Brønsted acidic sites of zeolite. Herein, chemical liquid deposition (CLD) method was adopted to passivate the external strong Brønsted acid of Ga/HZSM-5, aiming to increase the most value-added BTX production by suppressing the undesired propane cracking reaction. The content of deposited SiO2 on the external surface of zeolite was tunable by varying the amount of liquid deposition reagent and duration time of CLD process. The results showed that an appropriate content of SiO2 on external surface of catalyst was beneficial to disable the external strong Brønsted acid sites. Due to depressing the undesired propane cracking reaction, BTX selectivity of 55% with propane conversion of 49% was achieved on Ga/Z5-4Si catalyst, higher than those of Ga/HZSM-5. Otherwise, prolonging the duration time of CLD process narrowed the micropore mouth size of zeolite, which could enhance the shape selective effect of Ga/ZSM-5 to increase the proportion of para-xylene in total xylene products.

Synthesis and characterization of Fe, Co, and Ni colloids in 2-mercaptoethanol

Metal colloids in 2-mercaptoethanol using nanoparticles (NPs) of iron (Fe), cobalt (Co), and nickel (Ni) were prepared by chemical liquid deposition method. Transmission electron microscopy, electron diffraction, UV-VIS spectroscopy, and scanning electron microscopy with electron dispersive X-ray spectroscopy characterized the resulting colloidal dispersions. The NPs exhibited sizes with ranges from 9.8 nm for Fe, 3.7 nm for Co, and 7.2 nm for Ni. The electron diffraction shows the presence of the metals in its elemental state Fe (0), Co (0), and Ni (0) and also some compounds FeO (OH), CoCo2S4, and NiNi2S4.

Promotion of the Ni/γ-Al2O3 catalyst for the hydrogenation of naphthalene by silica coating

The γ-Al2O3 was coated with silica through the chemical liquid deposition method with tetraethyl orthosilicate as a deposition agent. The effects of the silica coating on the reduction behaviors of nickel species, acidity and hydrogenation activities of the Ni/γ-Al2O3 catalysts were studied. The results show that the silica coating has a great promotion on the reduction behaviors of nickel species as the catalyst was activated under air atmosphere but little influence under H2. The acidity of the catalyst was improved by the silica coating. Therefore, the activities of Ni/γ-Al2O3 catalysts for the hydrogenation of naphthalene are promoted by the silica coating, but the promotion effects on the catalysts activated under air and H2 atmosphere are difference. The promotion on the catalyst activated under air is due to the enhancement of its reduction degree and acidity, but only acidity for the catalyst activated under H2. As a result, the activity is improved about 230% for the catalyst activated under air but only about 110% for the catalyst activated under H2.

Operando Dual Beam FTIR Study of Hydroxyl Groups and Zn Species over Defective HZSM-5 Zeolite Supported Zinc Catalysts

A series of defective ZSM-5 zeolites (~300 nm, SiO2/Al2O3 ratio of 55, 100, 480 and 950) were systematically studied by XRD, SEM, 29Si MAS NMR, argon physisorption, NH3-TPD and FT-IR technologies. The nature, the amount and the accessibility of the acid sites of defective ZSM-5 zeolites are greatly different from reported ZSM-5 zeolites with a perfect crystal structure. The Brønsted acid sites (Si(OH)Al) with strong acid strength and the Brønsted acid sites (hydroxyl nests) with weak acid strength co-existed over defective ZSM-5 zeolites, which leads to a unique catalytic function. Zn(C2H5)2 was grafted onto defective ZSM-5 zeolites through the chemical liquid deposition (CLD) method. Interestingly, FT-IR spectroscopic studies found that Zn(C2H5)2 was preferentially grafted on the hydroxyl nests with weak acid strength rather than the Si(OH)Al groups with strong acid strength over different defective ZSM-5 zeolites. In particular, home-built operando dual beam FTIR-MS was applied to study the catalytic performance of Zn species located in different sites of defective ZSM-5 zeolites under real n-hexane transformation conditions. Results show that Zn species grafted over hydroxyl nests obtain better dehydrogenative aromatization performance than Zn species over Si(OH)Al groups. This study provides guidance for the rational design of highly efficient alkane dehydrogenative aromatization catalysts.

Novel near infrared reflective pigments based on hollow glass microsphere/BiOCl1-xIx composites: Optical property and superhydrophobicity

In this work, BiOCl1-xIx coated hollow glass microsphere was synthesized as a novel near infrared reflective pigment for superhydrophobic cool roof coatings. BiOCl1-xIx microflowers or microspheres were deposited on hollow glass microspheres using a simple chemical liquid deposition method. The morphologies of BiOCl1-xIx were found to differ drastically by varying the molar ratio of Cl to I. The color of the composite pigments changed from white to red and the band gap decreased from 3.16 eV to 1.87 eV as the increased content of I. The near infrared solar reflectance of the composite pigment was as high as 0.947. An approximately 8 °C decrease in outer surface temperature was obtained for the heat box coated with the composite pigments. With the help of the micro/nano-scale surface roughness of hollow glass microsphere/ BiOCl1-xIx composites, a superhydrophobic coating with a contact angle of 156.1° could be obtained. The superhydrophobic cool coating showed good antifouling property when they were fouled by the slurry solution containing montmorillonite and Rhodamine B. Moreover, the prepared superhydrophobic coatings exhibited long term stability and ultraviolet durability. Therefore, such superhydrophobic cool coatings with antifouling property is able to work for a longer time by preventing the contamination for building thermal insulation.

Optical property and thermal performance of hollow glass microsphere/BiOBr1-xIx composites as a novel colored near infrared reflective pigment

In this work, hollow glass microsphere/BiOBr1-xIx composites was synthesized as a series of novel colored near infrared reflective pigments. BiOBr1-xIx microflowers or microspheres were deposited on hollow glass microspheres using a simple chemical liquid deposition method. The morphologies and optical properties of the composite pigments were found to differ drastically by varying the molar ratio of I to Br. The color of the composite pigments was observed to turn from white to yellow, and then to red as the increased content of I. The band gap of the composites decreased from 2.87 to 1.87 eV with increasing I content. The near infrared solar reflectance of hollow glass microsphere/BiOBr1-xIx composite pigments was as high as 0.952. An approximately 9.4 °C decrease in outer surface temperature was obtained for the heat box coated with the composite pigments. Therefore, the synthesized composite pigments with tunable colors and high NIR reflectance have the potential to be applied as cool pigments in cool coatings to reduce the heat build-up.

Color performance and near infrared reflectance property of novel yellow pigment based on Fe2TiO5 nanorods decorated mica composites

To obtain cool yellow pigments with high near-infrared reflectance, mica/Fe2TiO5 composite pigments were synthesized by a chemical liquid deposition method. The developed composite pigment powders were characterized by X-ray diffraction (XRD), scanning electronic microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV–vis–NIR diffuse reflectance spectra, and CIEL*a*b* color scales. Different sized Fe2TiO5 nanorods were coated on the surface of mica particles. The particle size of the nanorods increased with increasing molar ratio of Fe3+ to Ti4+. The obtained composite pigments showed strong ultraviolet shielding ability and high near-infrared reflectance property. What's more, the Fe2TiO5 coating with smaller particle size possessed higher reflectance in the region of 700–1500 nm in accordance with the Kubelka-Munk theory. The near-infrared solar reflectance of mica/Fe2TiO5 composites was as high as 80.3%. An approximately 3 °C decrease in interior temperature was obtained for the heat box coated with the composite pigments. Furthermore, the composite pigments exhibit brilliant yellow colors. Therefore, mica/Fe2TiO5 composites are excellent near infrared reflective yellow pigments for efficient solar reflective coatings.

Chitosan doped with nanoparticles of copper, nickel and cobalt

Metal colloids in 2 propanol using nanoparticles (NPs) of copper, nickel and cobalt were prepared by Chemical Liquid Deposition (CLD) method. The resulting colloidal dispersions were characterized by Transmission Electron Microscopy (TEM). The colloids were supported in chitosan. Then, microbiological assays were performed using E. coli and S. aureus in order to determine the bactericide/bacteriostatic activity of nanoparticles (NPs) trapped or chelated with chitosan.Finally, the toxicity of the metal colloids Cu, Ni and Co was tested. Bio-assays were conducted in three different animal species. First of all on earth warms (Eisenia foetida) to evaluate the toxicity and the biocompatibility of chitosan in lactic acid (1% and 0.5%). Secondly bio-assay done in fishes (rainbow trout), the liver toxicity of NPs in vivo was evaluated. Finally, a bio-assay was conducted in Sprange-Dawley rats of 100g weight, which were injected intraperitoneally with different solutions of chitosan metal colloids. Then, the minimum and maximum concentration were determined for copper, nickel and cobalt. The purpose of the use of chitosan was acting as a carrier for some magnetic NPs, which toxicity would allow to obtain new polymeric materials with potential applications as magnet future drugs carrier.

Effect of Iron Coating on Thermal Properties of Aluminum‐Lithium Alloy Powder

AbstractAluminum‐lithium alloys are widely studied to improve performance in energetic materials. However, their high reactivity causes severe surface oxidation over micro‐Al particles in storage, resulting in significant deterioration in the overall performance. This study deals with the effect of iron coating on thermal properties and aging stability of aluminum‐lithium alloy powder. Gas atomized Al‐3Li (3 wt. %) alloy powder was prepared and then successfully coated with nano‐sized iron film by modified chemical liquid deposition method. The morphology, thermal properties and combustion enthalpies were characterized by SEM/EDX, TG/DTA and oxygen bomb calorimeter. The results showed that Fe/Al‐3Li composite powder presented obvious core‐shell structure and the outer iron film was very uniform and compact. Significantly enhanced thermal reactivities of Al‐3Li alloy powder and Fe/Al‐3Li composite powder were achieved compared with pure Al. In addition, aging studies indicated that, after coating, the reactivity decay rates of alloy powder decreased significantly, and the mass combustion enthalpies remained basically stable, which demonstrated that iron coating indeed prevented pre‐oxidation of the alloy powder and improved its aging stability.

Investigation on the film-coating mechanism of alumina-coated rutile TiO2 and its dispersion stability

The alumina and alumina-coated rutile TiO2 samples were synthesized by the chemical liquid deposition method under various pH values and aging temperature. The prepared samples were characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), ζ-potential as well as X-ray photoelectron spectroscopy (XPS). The relationship between pH values, the dispersion stability, crystalline types and microstructure of alumina-coated rutile TiO2 samples were studied. It is indicated that the coating film exhibited amorphous hydrous alumina (at pH 3–7), boehmite (at pH 7–9) and bayerite (pH > 11), respectively. And the higher aging temperature was in favor of the elevation of boehmite content of coating film. As the boehmite content increased, the dispersion stability was gradually enhanced and the prepared sample exhibited optimum dispersion stability at pH 9 and aging temperature 200°C, respectively. The increase of steric hindrance and electrostatic repulsion led to the promotion of dispersion stability via coating hydrous alumina film on the surface of rutile TiO2. The detection of AlO and the significantly enhancement of AlOTi intensity confirmed that the film coating process should be main attributed to both chemical bonding and physical adsorption.

Application of SnO2 nanoparticle as sulfide gas sensor using UV/VIS/NIR spectrophotometer

Sulfide gas monitoring is required to protect organisms from its toxicity. Nanoparticles of metal oxides have characteristics that applicable as sensors for controlling environmental pollution like sulfide gas. Thin film of SnO2 as one part of the sulfide gas sensor was synthesized with the chemical liquid deposition method, and characterized by UV/VIS/NIR-Spectrophotometer before and after gas application, also using FTIR, SEM and XRD. Characterization studies showed nanoparticle sizes from the diameters range of 38-71 nm. Application of SnO2 thin film to sulfide gas detected by UV/VIS/NIR Spectrophotometer with diffuse reflectance showed chemical reaction by the shifting of maximum % R peak at wavelength of 1428 cm. The benefit of measurement of sulfide gas using this SnO2 nano thin film is that it could be done at the room temperature.

Synthesis and Characterization of CuO Nanoparticles by the Chemical Liquid Deposition Method and Investigation of its Catalytic Effect on the Thermal Decomposition of Ammonium Perchlorate

Synthesis and Characterization of CuO Nanoparticles by the Chemical Liquid Deposition Method and Investigation of its Catalytic Effect on the Thermal Decomposition of Ammonium Perchlorate

Catalytic cracking of 1-butene to propylene using modified H-ZSM-5 catalyst: A comparative study of surface modification and core-shell synthesis

Surface modification of ZSM-5 catalyst was carried out by silica deposition using chemical liquid deposition (CLD) method as well as core-shell silicalite composite material by hydrothermal method. The modified ZSM-5 catalyst was characterized using various physiochemical methods such as XRD, TPD, N2 adsorption-desorption and SEM analysis. Catalytic cracking of 1-butene was carried out using modified ZSM-5 catalysts. The propylene yield was higher for core-shell silicalite composite as compared to silica deposition through CLD method. Silica deposited using CLD method showed propylene-to-ethylene (P/E) ratio of 1.7, whereas core-shell silicalite composite resulted in P/E ratio of 3.0. The higher selectivity to light olefins using core-shell silicalite composite to be attributed to weak acid sites and effective control of external acid sites, which reduces the hydrogen transfer reactions that form alkanes and aromatics. The effective external surface passivation was verified using catalytic cracking of triisopropyl benzene. The core-shell silicalite composite showed excellent stability over 50h for the cracking of 1-butene stream.

Samarium colloids prepared in organic solvents and active solids

Samarium colloids in organic solvents (2-methoxyethanol, 2-propanol, 2-propanone, and 1,2-dimethoxyethane) were obtained by the chemical liquid deposition (CLD) method at 77 K. The colloids were characterized by electron diffraction, energy-dispersive X-ray (EDX), UV-Vis spectroscopy, kinetic stability, and electrophoretic measurements. The colloid stability depends on the solvent used and the metal concentration. The higher stability was obtained in 2-methoxyethanol, which is in agreement with previous results for other lanthanide colloids. The zeta potential (ζ) of the colloids ranges between 0.138 and 1.945 mV. The UV-Vis spectra exhibit bands characteristic of the solvent. The 2-methoxyethanol shows bands at 205 and 234 nm very similar to the 2-propanol which exhibits bands at 202 and 253 nm for 2.5E−4 M concentration. However, bands for 1,2-dimethoxyethane and 2-propanone colloids were impossible to determine due to their highest extinction coefficient values. A dependence of the UV/Vis spectral properties of these new sol materials with Sm(III) is described. In all cases, the EDX analyses confirm the presence of metal in the colloids. The electron diffraction gives the most common (hkl) planes corresponding to Sm and Sm2O3 (211) and (100), respectively. As shown by the particle size distribution determined from transmission electron microscopy (TEM), the Sm-2-methoxyethanol colloids exhibit ranges from 1.6 and 2.9 nm, but the Sm-2-propanol colloids show ranges from 2.3 to 2.5 nm; the medium particle size of Sm-1,2-dimetoxyethane colloid is 0.8 nm, and the Sm-2-propanone colloids have a range from 1.0 and 4.3 nm, exhibiting a solvent polarity dependence. Also, active solids from the evaporation of the colloids which have been fully characterized by several chemical and physical techniques have been obtained.