Bin Liao

Synthesis of Ag ion-implanted TiO2 thin films for antibacterial application and photocatalytic performance

TiO2 thin films were deposited by spin coating method. Silver ions were implanted into the films using a Metal Vapor Vacuum Arc implanter. The antibacterial ability of implanted films was tested using Escherichia coli removal under fluorescent irradiation and in the dark. The concentration of E. coli was evaluated by plating technique. The photocatalytic efficiency of the implanted films was studied by degradation of methyl orange under fluorescent illumination. The surface free energy of the implanted TiO2 films was calculated by contact angle testing. Vitamin C was used as radical scavengers to explore the antibacterial mechanism of the films. The results supported the model that both generation of reactive oxygen species and release of silver ions played critical roles in the toxic effect of implanted films against E. coli. XPS experimental results demonstrated that a portion of the Ag(Ag(3+)) ions were doped into the crystalline lattice of TiO2. As demonstrated by density functional theory calculations, the impurity energy level of subtitutional Ag was responsible for enhanced absorption of visible light. Ag ion-implanted TiO2 films with excellent antibacterial efficiency against bacteria and decomposed ability against organic pollutants could be potent bactericidal surface in moist environment.

Effect of Coil Current on the Properties of Hydrogenated DLC Coatings Fabricated by Filtered Cathodic Vacuum Arc Technique

We successfully prepared hydrogenated DLC (a-C:H) with a thickness higher than 25xa0μm on stainless steel using a filtered cathode vacuum arc (FCVA) technique. The structural and mechanical properties of DLC were systematically analyzed using different methods such as x-ray photoelectron spectroscopy, Raman spectroscopy, scanning electron microscopy, Vickers hardness, nanohardness, and friction and wear tests. The effect of coil current on the arc voltage, ion current, and mechanical properties of resultant films was systematically investigated. The novelty of this study is the fabrication of DLC with Vickers hardness higher than 1500xa0HV, in the meanwhile with the thickness higher than 30xa0μm through varying the coil current with FCVA technique. The results indicated that the ion current, deposition rate, friction coefficient, and Vickers hardness of DLC were significantly affected by the magnetic field inside the filtered duct.

The Influence of C2H2 Flow Rate on the Composition, Structural and Properties of the Ni/α-C:H Films Deposited by FCVA

Nickel/carbon nanocomposite films with different C2H2 flow rate were deposited by filtered cathodic vacuum arc (FCVA) device. The composition and nanostructure of the films were investigated by X-ray diffraction (XRD), Raman scattering spectroscopy, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The grain size increase from 8.7 nm at the C2H2 flow rate of 10 sccm to the maximum of 11.5 nm at 30 sccm, after that it decrease. The mean phase separation is in the range of 0.2-2.6 nm. The hardness of 21.6 Gpa was obtained at 50sccm.