Preparation and characterization of slice-like Cu2(OH)3NO3 superhydrophobic structure on copper foil

Superhydrophobic structure was prepared on copper foil via a facile solution-immersion method. Thus slice-like Cu₂(OH)₃NO₃ crystal was prepared on the surface of the copper foil by sequential immersing in an aqueous solution of sodium hydroxide and cupric nitrate. And the superhydrophobic structure was obtained by modifying the slice-like Cu₂(OH)₃NO₃ crystal with 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FAS-17). The morphologies, chemical compositions and states, and hydrophobicity of the surface-modifying films on the copper foil substrates were analyzed by means of scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and water contact angle measurement. Moreover, the thermal stability of the slice-like structure was also evaluated using thermogravimetric analysis (TGA). It was found that roughening of the copper foil surface helped to increase the hydrophobicity to some extent, but no superhydrophobicity was obtained unless the slice-like Cu₂(OH)₃NO₃ crystal formed on the Cu substrate was modified with 1H,1H,2H,2H-perfluorodecyltriethoxysilane. Besides, the superhydrophobicity of the FAS-17-modified slice-like Cu₂(OH)₃NO₃ structure was closely related to the surface morphology. And this hydrophobic structure retained good superhydrophobic stability at elevated temperature and in long-term storage as well, which should be critical to the application of Cu-matrix materials in engineering.     

Facile method to prepare stable superhydrophobic Co3O4 surface

A facile and novel method was developed to fabricate rough Co₃O₄ surface with hierarchical micro- and nanostructures by the combination of simple solid state reactions and coating process. After modification with stearic acid, a superhydrophobic surface with water contact angle of 155 ± 1.8° and sliding angle of 2° was obtained. The superhydrophobic Co₃O₄ surface remained superhydrophobic property in a wide pH range from 3 to 14. The superhydrophobic Co₃O₄ surface also showed excellent self-cleaning property and high stability in ambient environments.     

Synthesis and separation property of flower-like Cd(OH)2 microstructures via a simple solution route

Well-defined flower-like Cd(OH)₂ microstructures have been successfully synthesized via a simple aqueous solution route, using CdCl₂ and NaOH as the reactants, and triethanolamine (TEA) as the modifying agent. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV-vis spectrometer were used to characterize the products. SEM and TEM images illustrated that the flower-like Cd(OH)₂ bundles consisted of hexagonal nanoplates with thickness of about 50 nm. The adsorption of TEA on (0 0 1) plane of the growing Cd(OH)₂ crystal leads to the flower petals in appearance. Further experiments evidenced that the positively charged Cd(OH)₂ could effectively adsorb or separate the negatively charged dye molecules.     

Fabrication, characterization and photoelectrochemical properties of Fe2O3 modified TiO2 nanotube arrays

TiO₂ nanotube (NT) arrays modified by Fe₂O₃ with high sensibility in the visible spectrum were first prepared by annealing anodic titania NTs pre-loaded with Fe(OH)₃ which was uniformly clung to the titania NTs using sequential chemical bath deposition (S-CBD). The photoelectrochemical performances of the as-prepared composite nanotubes were determined by measuring the photo-generated currents and voltages under illumination of UV-vis light. The titania NTs modified by Fe₂O₃ showed higher photopotential and photocurrent values than those of unmodified titania NTs. The enhanced photoelectrochemical behaviors can be attributed to the modified Fe₂O₃ which increases the probability of charge-carrier separation and extends the range of the TiO₂ photoresponse from ultraviolet (UV) to visible region due to the low band gap of 2.2 eV of Fe₂O₃.     

Facile synthesis and capacitive performance of the Co(OH)2 nanostructure via a ball-milling method

Co(OH)₂ nanoparticles were synthesized using only CoSO₄·7H₂O and NaOH as reactants without other auxiliary reagents via a simple, low-cost and practical ball-milling technique and investigated as the active electrode materials for supercapacitors. The structure and morphology of the resulting Co(OH)₂ samples were examined by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and transmission electron microscopy (TEM). The observations revealed the formation of brucite-like phase of β-Co(OH)₂, which had an irregular sphere-like shape with an average size of 50-100 nm. When investigated as electrode materials for supercapacitors, the β-Co(OH)₂ exhibited good energy-storage performances in terms of high specific capacitance of 599 F g⁻¹ and excellent capacity retention, suggesting its potential application in the electrode material for supercapacitors.     

Preparation and characterization of Cu(In,Ga)(Se,S)2 films without selenization by co-sputtering from Cu(In,Ga)Se2 quaternary and In2S3 targets

In this study, Cu(In,Ga)(Se,S)₂ (CIGSS) thin films were deposited onto a bi-layer Mo coated soda-lime glass by co-sputtering a chalcopyrite Cu(In,Ga)Se₂ (CIGS) quaternary alloy target and an In₂S₃ binary target. A one-stage annealing process was performed to form CIGSS chalcopyrite phase without post-selenization. Experimental results show that CIGSS films were prepared by the proposed co-sputter process via CIGS (70 W by radio frequency) and In₂S₃ (30 W by direct current) with a substrate temperature of 373 K, working pressure of 0.67 Pa, and one-stage annealing at 798 K for 30 min. The stoichiometry ratios of the CIGSS film were Cu/(In + Ga) = 0.92, Ga/(In + Ga) = 0.26, and Se/(S) = 0.49 that approached device-quality stoichiometry ratio (Cu/(In + Ga) < 0.95, Ga/(In + Ga) < 0.3, and (Se/S) ≈ 0.5). The resistivity of the sample was 14.8 Ω cm, with a carrier concentration of 3.4 × 10¹⁷ cm⁻³ and mobility of 1.2 cm² V⁻¹ s⁻¹. The resulting film exhibited p-type conductivity with a double graded band-gap structure.     

Optical and electrical characterization of TiO2 nanotube arrays on titanium substrate

Novel oriented aligned TiO₂ nanotube (TN) arrays were fabricated by anodizing titanium foil in 0.5% HF electrolyte solution. It is indicated that the sizes of the TNs greatly depended on the applied voltages to some extent. The electrical properties of the TN arrays were characterized by current-voltage (I-V) measurements. It exhibits a nonlinear, asymmetric I-V characterization, which can be explained that there exists an n-type semiconductor/metal Schottky barrier diode between TN arrays and titanium substrate interface. The absorption edges shift towards shorter wavelengths with the decrease of the anodizing voltages, which is attributed to the quantum size effects. At room temperature, a novel wide PL band consisting of four overlapped peaks was observed in the photoluminescence (PL) measurements of the TN arrays. Such peaks were proposed to be resulted from the direct transition X₁ → X₂/X₁, indirect transition Γ₁ → X₂/X₁, self-trapped excitons and oxygen vacancies, respectively.     

Simulation of coexisting ferromagnetic order and disorder of geometrically frustrated Co2Cl(OH)3

The ground state and phase transition of Co₂Cl(OH)₃ were investigated by Monte Carlo simulation. This compound is a magnet, with a pyrochlore structure distorted along one axis. The magnetic structure at low temperatures consists of coexisting ferromagnetism and random spin, according to experiments. However, the formation mechanism of the coexistence and the interaction between the spins were unclear. We assumed an anisotropic Ising model and examined the ground state by multicanonical Monte Carlo simulation. In a nearest neighbor model, the ground states were highly degenerated. Almost all of the states were spin glass states, but a few of the states were ferromagnetic. The latter magnetic states were ferromagnetic at triangular layers and two in-one out random state at Kagome layers. The latter states should be stabilized if weak ferromagnetic interactions exist between second nearest neighbor spins and correspond to the states reported by the experiments. This expectation was confirmed by simulation.     

Hydrothermal synthesis of C-doped Zn3(OH)2V2O7 nanorods and their photocatalytic properties under visible light illumination

A visible light-driven photocatalyst, C-doped Zn₃(OH)₂V₂O₇, prepared by a hydrothermal method was studied. The as-prepared catalyst was characterized by SEM, XRD, DRS, and XPS, and exhibited efficient photocatalytic activity in the degradation of methylene blue (MB) under visible-light irradiation. Besides decoloring, the decomposition of MB was also observed, further demonstrating the performance of the photocatalyst. The carbon existing on the surface of Zn₃(OH)₂V₂O₇ nanorods was free and in carbide form. Dye degradation followed first-order kinetics, and was explained on the basis of the Langmuir-Hinshelwood mechanism.     

Synthesis and field emission of diamond-like carbon nanorods on TiO2/Ti nanotube arrays

Highly ordered TiO₂/Ti nanotube arrays were fabricated by anodic oxidation method in 0.5 wt% HF. Using prepared TiO₂/Ti nanotube arrays deposited Ni nanoparticles as substrate, high quality diamond-like carbon nanorods (DLCNRs) were synthesized by a conventional method of chemical vapor deposition at 750 °C in nitrogen atmosphere. DLCNRs were analyzed by filed emission scanning electron microscopy and Raman spectrometer. It is very interesting that DLCNRs possess pagoda shape with the length of 3–10 μm. Raman spectra show two strong peaks about 1332 cm⁻¹ and 1598 cm⁻¹, indicating the formation of diamond-like carbon. The field emission measurements suggest that DLCNRs/TiO₂/Ti has excellent field emission properties, a low turn-on field about 3.0 V/μm, no evident decay at 3.4 mA/cm² in 480 min.     

Highly ordered anodic TiO2 nanotube arrays and their stabilities as photo(electro)catalysts

Highly ordered TiO₂ nanotube arrays with an average diameter of 230 nm, a wall thickness of 30 nm and a length of 1.8 μm were fabricated within a large domain by electrochemically anodizing of a titanium foil in a mixed solution of glycerol and NH₄F aqueous electrolyte. The TiO₂ nanotubes exhibit an anatase structure after annealing at 450 °C in air for 3 h. The direct photolysis (DP), photocatalytic (PC), electrocatalytic (EC) and photoelectrocatalytic (PEC) activities of the TiO₂ nanotube arrays were investigated using methyl orange (MO) as the model pollutant. The degradation of MO in PC process is faster than that in DP process, which confirms the photocatalysis of TiO₂ nanotube arrays. The degradation rate in PEC process is much higher than those in EC and PC processes, which demonstrates the synergetic effect between PC and EC processes. The synergetic factor is 4.1, which suggests that the synergetic effect is strong. Moreover, the stabilities of morphology, structure and photo(electro)catalytic degradation performance of the TiO₂ nanotube arrays were studied in order to evaluate their applicability as photo(electro)catalysts. The photo(electro)catalytic experiments bring neither morphological nor structural modifications to the nanotube arrays. The photo(electro)catalytic degradation rates of the TiO₂ nanotube arrays maintain stable in 10 cycles, which indicates that the TiO₂ nanotube arrays are appropriate to be applied as photo(electro)catalysts.     

Formation of CdO films from chemically deposited Cd(OH)2 films as a precursor

Formation of cadmium hydroxide at room temperature onto glass substrates from an aqueous alkaline cadmium nitrate solution using a simple soft chemical method and its conversion to cadmium oxide (CdO) by thermal annealing treatment has been studied in this paper. The as-deposited film was given thermal annealing treatment in oxygen atmosphere at 450 °C for 2 h for conversion into cadmium oxide. The structural, surface morphological and optical studies were performed for as-deposited and the annealed films. The structural analyses revealed that as-deposited films consists of mixture of Cd(OH)₂ and CdO, while annealed films exhibited crystalline CdO. From surface morphological studies, conversion of clusters to grains after annealing was observed. The band gap energy was changed from 3.21 to 2.58 eV after annealing treatment. The determination of elementals on surface composition of the core-shell nanoparticles of annealed films was carried out using X-ray photoelectron spectroscopy (XPS).     

Synthesis and characterization of Cu2ZnSnSe4 nanotube arrays on fluorine-doped tin oxide glass substrates

Highly ordered arrays of Cu₂ZnSnSe₄ nanotubes have been successfully synthesized on fluorine-doped tin oxide glass substrate using ZnO nanorod arrays as sacrificial templates. The structure, morphology and optical properties of the Cu₂ZnSnSe₄ arrays were characterized by X-ray diffraction, Raman spectrometry, field-emission scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray, and UV–Vis absorption spectroscopy. The diameter and length of the Cu₂ZnSnSe₄ nanotubes can be adjusted by tuning the diameter and length of the ZnO nanorods. In addition, the effect of the length on the performance of the photoelectrochemical cells was also investigated.     

Influence of anodization parameters on the morphology of TiO2 nanotube arrays

TiO₂ nanotube arrays can be fabricated by electrochemical anodization in organic and inorganic electrolytes. Morphology of these nanotube arrays changes when anodization parameters such as applied voltage, type of electrolyte, time and temperature are varied. Nanotube arrays fabricated by anodization of commercial titanium in electrolytes containing NH₄F solution and either sulfuric or phosphoric acid were studied at room temperature; time of anodization was kept constant. Applied voltage, fluoride ion concentration, and acid concentrations were varied and their influences on TiO₂ nanotubes were investigated. The current density of anodizing was recorded by computer controlled digital multimeter. The surface morphology (top-view) of nanotube arrays were observed by SEM. The nanotube arrays in this study have inner diameters in range of 40-80 nm.     

Growth of Sn(O,S)2 buffer layers and its application to Cu(In,Ga)Se2 solar cells

Sn-based thin films as new buffer layer for Cd-free Cu(In,Ga)Se₂ (CIGS) solar cells were developed. The Sn(O,S)₂ films were formed on CIGS substrates by chemical bath deposition from an alkaline ammonia solution by reacting tin(IV) chloride with thiourea. Optimization of the growth process allowed the smooth and conformal coverage of the films on the CIGS substrates with a thickness of 20 nm that was a self-limited thickness in the chemical bath deposition process. XPS analysis revealed that the as-deposited films contained Sn–O, Sn–OH, and Sn–S bondings and the ratio of Sn–S bonding to Sn–O bonding was 0.3. The CIGS solar cell fabricated with a 20-nm thick Sn(O,S)₂ buffer layer had the best efficiency of 11.5% without AR coating. The open circuit voltage, short circuit current, and fill factor were 0.55 V, 34.4 mA/cm², and FF = 0.61, respectively. The open circuit voltage and fill factor were low compared to the conventional CIGS solar cell with a 50-nm thick CdS buffer due to too thin Sn(O,S)₂ buffer layer.     

Study of the electron paramagnetic resonance spectra of Zn(antipyrine)2(NO3)2:VO

In this work, a full ligand-field energy matrix (10×10) diagonalization treatment for 3d¹ ions in tetragonal symmetry is developed on the basis of the two-s.o.-coupling-parameter model. Spin Hamiltonian parameters (g factors g_∥, g_⊥ and hyperfine structure constants A_∥, A_⊥) of the tetragonal V⁴⁺ center in Zn(antipyrine)₂(NO₃)₂ are calculated from the complete energy matrix diagonalization method and the perturbation theory method. The calculated results from both methods are not only close to each other but also in good agreement with the experimental values. Furthermore, the compressed defect structure of V⁴⁺ center is discussed.     

花状NaY(MoO4)2的合成和(MoO4)2:Eu3+的光学性质

用微波辅助水热-煅烧法成功合成了花状NaY(MoO₄)₂颗粒,用XRD、XPS、FESEM进行了表征,提出了花状NaY(MoO₄)₂颗粒可能的形成机理. 采用相同的方法合成了NaY(MoO₄)₂:Eu³⁺荧光体,该荧光材料在612 nm处有一个强的发射峰,可用作白色发光二极管的红色磷光剂. 此外,微波辅助水热-煅烧法可能发展成为制备其他花状稀土钼酸盐的有效途径.     

The effect of Si surface nitridation on the interfacial structure and electrical properties of (La2O3)0.5(SiO2)0.5 high-k gate dielectric films

Thermal stability, interfacial structures and electrical properties of amorphous (La₂O₃)_0.5(SiO₂)_0.5 (LSO) films deposited by using pulsed laser deposition (PLD) on Si (1 0 0) and NH₃ nitrided Si (1 0 0) substrates were comparatively investigated. The LSO films keep the amorphous state up to a high annealing temperature of 900 °C. HRTEM observations and XPS analyses showed that the surface nitridation of silicon wafer using NH₃ can result in the formation of the passivation layer, which effectively suppresses the excessive growth of the interfacial layer between LSO film and silicon wafer after high-temperature annealing process. The Pt/LSO/nitrided Si capacitors annealed at high temperature exhibit smaller CET and EOT, a less flatband voltage shift, a negligible hysteresis loop, a smaller equivalent dielectric charge density, and a much lower gate leakage current density as compared with that of the Pt/LSO/Si capacitors without Si surface nitridation.     

Photoelectrochemical property and photocatalytic activity of N-doped TiO2 nanotube arrays

N-doped TiO₂ nanotube arrays (NTN) were prepared by anodization and dip-calcination method. Hydrazine hydrate was used as nitrogen source. The surface morphology of samples was characterized by SEM. It showed that the mean size of inner diameter was 65 nm and wall thickness was 15 nm for NTN. The ordered TiO₂ nanotube arrays on Ti substrate can sustain the impact of doping process and post-heat treatment. The atomic ratio of N/Ti was 8/25, which was calculated by EDX. Photoelectrochemical property of NTN was examined by anodic photocurrent response. Results indicated the photocurrent of NTN was nearly twice as that of non-doped TiO₂ nanotube arrays (TN). Photocatalytic activity of NTN was investigated by degrading dye X-3B under visible light. As a result, 99% of X-3B was decomposed by NTN in 105 min, while that of TN was 59%.     

Facile fabrication of Zn/Zn5(OH)8Cl2·H2O flower-like nanostructure on the surface of Zn coated with poly (N-methyl pyrrole)

Zn/Zn₅(OH)₈Cl₂·H₂O flower-like nanostructures was electrodeposited on the coated Zn with poly (N-methyl pyrrole) in 0.1 M Zn (NO₃)₂ and 0.1 M KCl solution. The morphology and the structure of the Zn/Zn₅(OH)₈Cl₂·H₂O were characterized by Field Emission Scanning Electron Microscopy (FESEM), Fourier transform infrared (FT-IR) spectroscopy and X-ray diffraction analysis (XRD). The FT-IR results showed special peaks at 908 and 728 cm⁻¹ related to Zn₅(OH)₈Cl₂·H₂O. The FESEM results indicated that Zn/Zn₅(OH)₈Cl₂·H₂O consists of a flower-like nanostructure and these flower-shaped structures contain many shaped nanopetals with the thickness of 27.8 nm. The XRD result confirmed that the major phase of electrodeposited product in 0.1 M KCl as supporting electrolyte was Zn₅(OH)₈Cl₂·H₂O. The ability of PMPy to create a thin film and the existence of several pores in its matrix act as a mold for the growth of Zn/Zn₅(OH)₈Cl₂·H₂O flower-like nanostructure. The trapping of Cl⁻ and OH⁻ within pores can be considered as the reason for the formation of flowerlike Zn/Zn₅(OH)₈Cl₂·H₂O nanostructures in 0.1 M KCl.