Zhongwei Liu

Atomic layer deposition of nickel carbide for supercapacitors and electrocatalytic hydrogen evolution

We report a new atomic layer deposition (ALD) process for nickel carbide (Ni3C). The process uses bis(1,4-di-tert-butyl-1,3-diazabutadienyl)nickel(II) and H2 plasma and is able to produce smooth, pure, crystalline Ni3C thin films in an ideal self-limiting ALD growth fashion. Using this ALD process, a uniform thin layer of Ni3C can be conformally coated on carbon nanotubes (CNTs) to afford a core–shell nanostructured Ni3C/CNT composite. The ALD-prepared Ni3C/CNT composite is demonstrated to show excellent performance for supercapacitors and electrocatalytic hydrogen evolution.

The Spatiotemporal Pattern Formed in an Atmospheric-Pressure Radio-Frequency Dielectric-Barrier-Discharge Oxygen Plasma

In this paper, we developed a radio-frequency (RF) dielectric barrier oxygen discharge, which consists of a powered brass electrode covered by fused silica as a dielectric layer and a grounded liquid electrode. The self-organized patterns in the RF dielectric barrier discharge at atmospheric pressure are investigated. With increasing the input power, the plasma patterns transform from the ring to the netlike structure.

Influence of the Solution on Adhesion Layer Polymerized in Radio Frequency Pulsed Plasma for DNA Hybridization Assay

A radio frequency (RF) pulsed plasma polymerized allylamine (PPPAA) film as an adhesion layer to adsorb DNA probe and then hybridize with a complementary or a mismatch DNA target is investigated in this paper. The possible application of plasma polymerization film as an adhesion layer for DNA hybridization assay is evaluated by DNA hybridization reactions. It was found, by surface plasmon enhanced fluorescence spectroscopy (SPFS), that the DNA hybridization reactions in phosphate buffered saline (PBS) solution can be remarkably revealed by fluorescence signals, but it heavily depends on the solution conditions. The influence of the solution pH value and the ionic strength on the PPPAA film thickness and adsorption is explored in detail.

The Antibacterial Polyamide 6-ZnO Hierarchical Nanofibers Fabricated by Atomic Layer Deposition and Hydrothermal Growth

In this paper, we report the combination of atomic layer deposition (ALD) with hydrothermal techniques to deposit ZnO on electrospun polyamide 6 (PA 6) nanofiber (NF) surface in the purpose of antibacterial application. The micro- and nanostructures of the hierarchical fibers are characterized by field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HRTEM), and scanning transmission electron microscopy (STEM). We find that NFs can grow into “water lily”- and “caterpillar”-like shapes, which depend on the number of ALD cycles and the hydrothermal reaction period. It is believed that the thickness of ZnO seed layer by ALD process and the period in hydrothermal reaction have the same importance in crystalline growth and hierarchical fiber formation. The tests of antibacterial activity demonstrate that the ZnO/PA 6 core-shell composite fabricated by the combination of ALD with hydrothermal are markedly efficient in suppressing bacteria survivorship.

Formation and characteristics of patterns in atmospheric-pressure radio-frequency dielectric barrier discharge plasma

The patterns in radio-frequency dielectric barrier discharge (RF DBD) are studied at atmospheric pressure of argon (Ar) or helium (He) mixed with nitrogen (N2) gas. When a small amount of N2 is mixed with He or Ar gas, discharge patterns are formed. In a N2/He gas mixture, besides the filament discharge that forms patterns, a glow background discharge is also observed, whereas only the filament discharge forms patterns in a N2/Ar gas mixture. The resolution of the hexagonal pattern as a function of applied power and gas flow rate is then explored. On the basis of spatial–temporal images taken using an intensified charge-coupled device (ICCD), we find that there is no interleaving of two transient hexagon sublattices in N2/Ar or N2/He plasma in RF DBD patterns, which are totally different from those in which surface charges dominated in the mid-frequency DBD plasma. This supports our hypothesis that the bulk charges dominate the pattern formation in RF DBD.

The modification of Lithium ion battery separator by SiOx coatings

Summary form only given. SiOx coating was deposited on the surface of Lithium ion battery separators by means of electron beam evaporation technique in vacuum evaporator. Hexamethyldisoloxane (HMDSO) was ionized by plasma and doped into the SiOx coating during the deposition process. The thermal performances of the separator were tested by TGA (Thermogravimetric Analysis), DSC (Differential Scanning Calorimetry) and TMA (Thermal Mechanical Analysis). The wettability was measured by water contact angle. There is no significantly reduction for the mechanical performance of the membrane after coated the as-doped SiOx. The thermal shrinkage is significantly improved, and the heat resistance and the wettability increase to some degree.

Deposition of siox oxygen barrier films by atmospheric pressure plasma jet

Summary form only given. Atmospheric pressure plasma jet is a relatively new source of non-equilibrium atmospheric pressure plasmas. Compared to other techniques such as plane-parallel electrodes DBDs, the jet can be used for not only flat and thin substrates but large three-dimensional structures, because the jet is not limited by electrodes and the dimension of emerging plasma varies from several cm down to the sub-mm region. The present work reports the deposition of silicon dioxide film on polyimide (PI) samples by atmospheric pressure plasma jet (APPJ), which operates by feeding the mixture of hexamethyldisiloxane (HMDSO) and nitrogen between two coaxial electrodes that are driven by a 20.8 kHz power source. The films were analyzed using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and FT-IR spectroscopy. The film barrier properties have been improved remarkably. In certain experimental conditions (input power 250 W, nitrogen flow rate 10 SLM), the oxygen transmission rate decreases from virgin PI 160 cc/(m2 day atm) to 0.8 cc/(m2 day atm). The effects of process parameters, such as discharge input power, nitrogen flow rate and reaction position on film barrier property have been investigated.