Songmiao Liang

The study of interaction between graphene and metals by Raman spectroscopy

Different metal films (Co, Ni, Au, and Ag) were deposited on graphene and the interactions between these metals and graphene were studied by Raman spectroscopy. The Raman peaks were shifted after the deposition of metal films. The electron doping of graphene with cobalt contacts and the hole doping with the nickel contacts are the main reasons for Raman peak shift. However, for gold contacts and silver contacts with graphene, strain effect dominates Raman peak shift instead of charge transfer.

High‐Strength Cellulose/Poly(ethylene glycol) Gels

Cellulose gel membranes have been prepared by a pre-gelation method employing cellulose solutions in aqueous NaOH-thiourea obtained at low temperature. The cellulose gels were then swollen by low-molecular-weight polyethylene glycol (PEG; MW<1000 g mol(-1)), and the morphology, structure and mechanical properties of the cellulose/PEG gels were studied by various techniques. The gels exhibit high mechanical performance, and the tensile strength of the gel membranes increases sharply with an increase in the molecular weight of PEG from 200 to 800 g mol(-1). Moreover, their elongation at break remains stable at 100 %. PEG800 efficiently improves the optical transmittance of the gel membranes at ambient temperature, which is about five times greater than that of a normal cellulose hydrogel membrane. A strong hydrogen-bonding interaction occurs between PEG and cellulose leading to a homogeneous structure, high mechanical strength and good transparency of the gel membranes.

Multi-membrane hydrogel fabricated by facile dynamic self-assembly

Multi-membrane hydrogels are newly promising carriers in biomedical fields. We fabricate alginate-based onion-like multi-membrane hydrogels starting from a template gel-core to shells through a dynamic self-assembly method, and investigate the influence of various factors on the formation of the complex system in detail. By precisely controlling the process of preparation, multi-layered hydrogels of different shapes either with or without defined internal space between separated layers can be prepared. And a pulse-like delivery of macromolecule has been achieved by this architecture.

Comparative study of n-MgZnO/p-Si ultraviolet-B photodetector performance with different device structures

A comparative study of n-MgZnO/p-Si UV-B photodetector performance was carried out with different device structures. The experimental results demonstrate superior photoresponse characteristics of the p-n heterojunction detector against the Schottky type metal-semiconductor-metal counterpart, including a sharper cutoff wavelength at 300 nm, a larger peak photoresponsivity of 1 A/W, and a faster response speed. The role of built-in field and low interface scattering in p-n heterojunction is explored, and the energy band diagram of n-MgZnO/p-Si is employed to interpret the efficient suppression of visible light photoresponse from Si substrate, revealing the applicability of this heterostructure in fabrication of deep ultraviolet detectors.

Facile fabrication of robust superhydrophobic porous materials and their application in oil/water separation

Utilizing superhydrophobic porous materials in oil/water separation has attracted increasing research interest, however, most of these materials are usually complicated to fabricate or easily lose their functions in harsh circumstances. In this study, dispersion of poly[(3,3,3-trifluoropropyl)methylsiloxane] (PTFPMS) micro–nano aggregations in acetone/water was facially prepared via a simple phase separation method. The aggregations can be easily coated on the skeletons of various 2D and 3D porous substrates, endowing the porous materials with superhydrophobicity. The prepared superhydrophobic materials show excellent resistance to chemical erosion, mechanical abrasion, and high temperature (up to 400 °C). This robust superhydrophobicity promises application of the resultant porous materials in harsh environments, and examples of using these superhydrophobic porous materials to separate oil/water mixtures have been demonstrated. This simple and universal method is suitable for the large-scale preparation of porous materials with robust superhydrophobicity.

Robust Polypropylene Fabrics Super-Repelling Various Liquids: A Simple, Rapid and Scalable Fabrication Method by Solvent Swelling

A simple, rapid (10 s) and scalable method to fabricate superhydrophobic polypropylene (PP) fabrics is developed by swelling the fabrics in cyclohexane/heptane mixture at 80 °C. The recrystallization of the swollen macromolecules on the fiber surface contributes to the formation of submicron protuberances, which increase the surface roughness dramatically and result in superhydrophobic behavior. The superhydrophobic PP fabrics possess excellent repellency to blood, urine, milk, coffee, and other common liquids, and show good durability and robustness, such as remarkable resistances to water penetration, abrasion, acidic/alkaline solution, and boiling water. The excellent comprehensive performance of the superhydrophobic PP fabrics indicates their potential applications as oil/water separation materials, protective garments, diaper pads, or other medical and health supplies. This simple, fast and low cost method operating at a relatively low temperature is superior to other reported techniques for fabricating superhydrophobic PP materials as far as large scale manufacturing is considered. Moreover, the proposed method is applicable for preparing superhydrophobic PP films and sheets as well.

Interface engineering of high-Mg-content MgZnO/BeO/Si for p-n heterojunction solar-blind ultraviolet photodetectors

High-quality wurtzite MgZnO film was deposited on Si(111) substrate via a delicate interface engineering using BeO, by which solar-blind ultraviolet photodetectors were fabricated on the n-MgZnO(0001)/p-Si(111) heterojunction. A thin Be layer was deposited on clean Si surface with subsequent in situ oxidation processes, which provides an excellent template for high-Mg-content MgZnO growth. The interface controlling significantly improves the device performance, as the photodetector demonstrates a sharp cutoff wavelength at 280 nm, consistent with the optical band gap of the epilayer. Our experimental results promise potential applications of this technique in integration of solar-blind ultraviolet optoelectronic device with Si microelectronic technologies.

Electronic transport of the manganite-based heterojunction with high carrier concentrations

The transport property of the manganite heterojunction La0.9Ca0.1MnO3+δ∕SrTiO3 (doped by 1wt%Nb) has been experimentally studied. The most important results of the present work are the discovery of the charge tunneling-dominated transport process, characterized by the appearance of the rectifying behaviors fairly described by the Newman equation I∝exp(αT)exp(βV) in a considerable temperature range (α and β are constants, and I and V are current and voltage, respectively). Significant modification of magnetic field to charge tunneling is also observed. It is believed that magnetic field depresses junction resistance by reducing depletion width of the junction.

Rectifying properties of magnetite-based Schottky diode and the effects of magnetic field

Rectifying properties, with and without magnetic field, of a high quality Fe3O4∕SrTiO3:Nb Schottky diode have been experimentally studied. The junction exhibits an excellent rectifying behavior both below and above the Verwey temperature (TV) of Fe3O4. Magnetic field has a weak but visible effect on the transport process of the junction, producing a negative magnetoresistance for T TV. Based on an analysis of the current-voltage characteristics, the spin polarization of Fe3O4 has been deduced. It is a strong function of temperature, varying between −78% and 18%.

Charge ordering transition near the interface of the (011)-oriented La1−xSrxMnO3 (x∼1/8) films

Two clear phase transitions, an insulator to metal transition followed by a metal to insulator transition on cooling, were realized in La1−xSrxMnO3 (x∼1/8) (LSMO) thin films grown on (011) SrTiO3 substrates due to the substrate-imposed anisotropic stain. Effects of phase transitions on the rectifying behavior of the corresponding junction LSMO/Nb:SrTiO3 were further investigated. The paramagnetic/insulator to ferromagnetic/metal transition led to a decrease in built-in potential of the junction, while the metallic to charge/orbital ordering transition results in a growth of interfacial barrier, which could be explained by Fermi-level shifts and the gap opening/closing in LSMO films. These results indicate the occurrence of clear phase transitions in the vicinity of interface in (011)-LSMO films.