Zhishen Wu

Study on an antiwear and extreme pressure additive of surface coated LaF3 nanoparticles in liquid paraffin

Abstract A LaF 3 nanoparticle surface coated by organic compounds containing S and P was synthesized by the chemical surface modification method. The particle size and structure were characterized using a transmission electron microscope (TEM) and electron diffraction (ED), their tribological behaviors were evaluated on a four-ball machine. The results showed that LaF 3 nanoparticles as an oil additive can strikingly improve the load-carrying capacity and antiwear property of the base oil and had better friction-reduction when compared to that of ZDDP. The rubbed surfaces were investigated by scanning electron microscopy (SEM) and X-ray photoelectron spectroscope (XPS). It can be found that the boundary film on the worn surface was composed of LaF 3 nanoparticles depositing film and tribochemical reaction film of the elements of S and P, which contributed to excellent tribological properties of LaF 3 nanoparticle modified by compound containing S and P as an additive in liquid paraffin.

Superhydrophobic and superoleophilic nanoparticle film: synthesis and reversible wettability switching behavior.

The present work describes a one-step facile spray deposition process for the fabrication of superhydrophobic and superoleophilic nanoparticle film. The film shows fast response wettability transition between superhydrophobicity and hydrophilicity. The reversible superhydrophobicity to hydrophilicity switching can be easily carried out by adjusting the temperature. The film also demonstrates oil uptake ability and can selectively adsorb oil floating on water surface. Furthermore, the film surface shows the antifouling performance for organic solvents, which can self-remove the organic solvents layer and recover its superhydrophobic behavior. The advantage of the present approach is that the damaged film can be easily repaired by spraying again.

Preparation and Tribological Properties of Surface-Capped Copper Nanoparticle as a Water-Based Lubricant Additive

Abstract Cu nanoparticle surface-capped by methoxylpolyethyleneglycol xanthate was synthesized using in situ surface-modification technique. The size, morphology and phase structure of as-prepared Cu nanoparticle were analyzed by means of X-ray diffraction and transmission electron microscopy. The tribological properties of as-synthesized Cu nanoparticle as an additive in distilled water were investigated with a four-ball machine, and the morphology and elemental composition of worn steel surfaces were examined using X-ray photoelectron spectroscopy and scanning electron microscope equipped with an energy-dispersive spectrometer attachment. Results show that as-synthesized Cu nanoparticle as a water-based lubricant additive is able to significantly improve the tribological properties and load-carrying capacity of distilled water, which is ascribed to the deposition of Cu nanoparticles on steel sliding surfaces giving rise to a protective and lubricious Cu layer thereon. In the meantime, they may also tribochemically react with rubbing steel surfaces to generate a boundary lubricating film consisting of Cu, FeS and FeSO4 on the rubbed steel surface, which helps to result in greatly improved tribological properties of distilled water, thereby reducing friction and wear of the steel–steel pair.

Preparation of In2S3 nanopraricle by ultrasonic dispersion and its tribology property

In this paper, we describe a facile and rapid method for preparing In2S3 nanoparticles via ultrasound dispersion. This method allows us to prepare In2S3 nanoparticles from bulk indium and sulfur with ease and without using expensive agents and in a short time. The possible growing mechanism of the In2S3 nanoparticles was presented. In addition, we provide detailed characterizations including TEM, XRD, TG-DTA, and XPS to study the shape, composition and structure of In2S3 nanoparticles. We also studied the tribology property of In2S3 nanoparticles made using this novel recipe.

Facile fabrication of stable superhydrophobic films on aluminum substrates

Compact and uniform layered double hydroxides thin films were fabricated on aluminum substrates using a simple solution-immersion process; upon chemical modification with perfluorosilane, the wettability of the aluminum surface changed from hydrophilic to superhydrophobic. The products were characterized by scanning electron microscopy, X-ray powder diffraction, and X-ray photoelectron spectroscopy. It is confirmed that the synergic effect of the surface morphology and the surface free energy contribute to this unique surface water repellence. In addition, the superhydrophobic films possess long-term storage stability and good adhesion strength to aluminum substrates, which enhance their potential practical applications.

Coaction of Sub-band and Doped Nitrogen on Visible Light Photoactivity of N-Doped TiO2

We found in our previous work that the high photoactivity of N‐doped TiO2 for the oxidation of propylene under visible light was attributed to the photoactive center Vo•‐NO‐Ti and the formation of sub‐band originated from a large amount of single‐electron‐trapped oxygen vacancies (denoted as Vo•; C. X. Feng, Y. Wang, Z. S. Jin, J. W. Zhang, S. L. Zhang, Z. S. Wu, Z. J. Zhang [2008], New J. Chem. 32, 1038). In the present study, the structure of the sub‐band within Eg of a representative sample N‐NTA‐400 was investigated by means of photoluminescence (PL) spectrometry and ultraviolet‐visible light‐near infrared diffuse reflectance spectra. The coaction of the sub‐band and doped nitrogen on visible light photocatalytic activity of N‐doped TiO2 was also investigated. The electron spin resonance spectra measured under laser irradiation (λ = 532 nm) indicate that the doped nitrogen may contribute to stabilize the trapping electron center, i.e. surface oxygen vacancy (Vo••), and hence suppress the PL, enhancing the photocatalytic activity.

Electrochemical lithium storage capacity of nickel mono-oxide loaded anatase titanium dioxide nanotubes

The NiO loaded anatase TiO2 nanotubes have been successfully synthesized. It was found that NiO nanoparticles could prevent the nanotubular morphology from destruction during the dehydration of interlayered –OH groups of NTA and improve the electronic conductivity of TiO2 nanotubes. Galvanostatic battery testing showed that the NiO loaded anatase TiO2 nanotubes electrode exhibit excellent rate capability and good cycle performance. The enhanced performances can be attributed to its favorable tubular morphology and the better electrical contact between NiO and TiO2 nanotubes.

The Effect Of Crystal Form Of N-Doped Titanium Dioxide On Visible-Light Photocatalytic Activity

TiO2 samples with different crystal forms were treated in flowing NH3 at elevated temperatures to fabricate N-doped TiO2 photocatalysts with different crystal forms. The resulting N-doped TiO2 photocatalysts were characterized by means of X-ray diffraction, transmission electron microscopy, diffusion reflectance spectrometry, and X-ray photoelectron spectroscopy. The visible-light photocatalytic activity of the catalysts was evaluated by measuring the photocatalyzed removal rate of propylene. Results indicate that the visible-light activity of N-doped TiO2 photocatalysts is highly dependent on the crystal form. Namely, N-doped anatase TiO2 has the highest visible-light activity, while the visible-light activity of N-doped TiO2 photocatalysts decreases with decreasing content of anatase phase and increasing content of rutile phase. In addition N-doped rutile TiO2 has no visible-light photocatalytic activity.

Ionic Liquid-assisted Solvothermal Synthesis of Ni Particles and Study of Their Electrocatalytic Effect for Calcium Dobesilate Oxidation

Graphical Abstract Ionic Liquid-assisted Solvothermal Synthesis of Ni Particles and Study of Their Electrocatalytic Effect for Calcium Dobesilate Oxidation

TiO2 Nanoparticles Functionalized by a Temperature-sensitive Poly(N-isopropylacrylamide) (PNIPAM): Synthesis and Characterization

TiO2 nanoparticles functionalized by poly(N-isopropylacrylamide), PNIPAM in short, were prepared via seeded emulsion polymerization of N-isopropylacrylamide (NIPAM) in the presence of N,N´-methylene-bis(acrylamide) (MBAA) as the crosslinking monomer. The morphology and structure of the TiO2/PNIPAM hybrid hydrogel were characterized by means of transmission electron microscopy, X-ray powder diffraction, and FT infrared spectroscopy. The response of the composite to temperature variations was also investigated. The results indicate that the title inorganic/organic hybrid has a sphere-like shape and is composed of inorganic TiO2 nanoparticles and a biocompatible polymer matrix, showing excellent thermosensitivity, as evident from relevant optical photographs at different temperatures. The thermosensitive TiO2 nanoparticles doped in PNIPAM matrix may have potential application in the remediation of wastewater streams.