Lin Hua Xia

MnO2/Graphene Nanocomposite for Use in High Performance Lithium-Ion Batteries

A facile hydrothermal route has been developed to prepare MnO2/graphene nanocomposites and MnO2 nanoparticles are uniformly anchored on graphene nanosheets. The composite were studied as the anode material for lithium-ion batteries. The surface of graphene is modified by MnO2 nanoparticles which are 10-30 nm in size and homogeneously anchor on graphene sheets. The composite exhibits superior lithium battery performance with higher reversible capacity and better cycling performance. The reversible capacity is up to 781.5 mAh g-1 at a current of 100 mA g-1 and maintains 96% after 50 cycles. The enhanced lithium storage performance is due to the synergetic effect of graphene and MnO2.

Graphene Modified Molecular Imprinted Electrochemical Sensor for Specific Recognition of Bovine Serum Albumin

A simple and efficient molecularly imprinted sensor (MIPs/GR/GCE) was firstly prepared by electropolymerization of pyrrole in the presence of bovine serum albumin (BSA) in an aqueous solution based on a graphene modified glassy carbon electrode for the selective recognition of bovine serum albumin. The prepared sensor was characterized by differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS), in which [Fe(CN)6]3−/4− was used as an electrochemical active probe. The results showed a wide linear range from 1.0 × 10-3 to 1.0 × 10-9 g/mL. And the imprinted biosensor indicated excellent selectivity and high sensitivity.

Crystal Growth and Optical Spectroscopy of Ytterbium-Doped Lutetium Orthophosphate

The flux growrh method is employed to grow the Yb:LuPO4 crystal using lead pyrophosphate Pb2P2O7 as the high-timperature solvent. The infrared spectroscopy(IR) was tested to determine the purity of the obtained crystal. The absorption spectra of the 5% Yb-doped Yb:LuPO4 crystal was measured at room temperature. Three absorption peaks that located on 985nm, 976nm and 953nm were found, and the absorption cross sections on the absorption peaks were calculated respectively. The results shows that Yb:LuPO4 crystal has potential to be applied as laser material.

Ultrasensitive Determination of Rutin on Ag Nanoparticles- Poly(p-aminobenzene sulfonic acid)/Graphene Modified Glassy Carbon Electrode

The Ag nanoparticles-Poly(p-aminobenzene sulfonic acid)/graphene modified glassy carbon electrode (AgNPs-PABSA/GR/GCE) was fabricated by electrodepositon of AgNPs-PABSA onto graphene modified glassy carbon electrode (GR/GCE). The reported method was simple and fast. Combining the advantages of GR (high surface area and good conductivity), AgNPs (excellent electronic conductivities) and PABSA (the ability to interact with many components through hydrophobic or π–π electronic interaction), the AgNPs-PABSA/GR modified electrode effectively improved the sensitivity for the determination of rutin.

Electrochemical Synthesis of Platinum-Reduced Graphene Oxide Hybrids for Methanol Oxidation

Reduced graphene oxide (RGO) supported platinum electrocatalyst was successfully synthesized on the glass carbon electrode by the electrodeposition method. Cyclic voltammetry (CV) and amperometry were used to evaluate the catalytic activity of the Pt/RGO modified electrode towards methanol oxidation. The results revealed that the as-prepared catalyst exhibited high electrocatalytic ability in methanol oxidation, which could be attributed to the excellent properties of the reduced graphene oxide as supporting materials.

Nafion/Quercetin/Graphene Composite-Modified Glassy Electrode for Selective and Sensitive Detection of Dopamine

Glassy carbon electrode (GCE) was modified using graphene (G), quercetin (Qu) and Nafion in this sequence to fabricate Nafion-Qu-G composite-modified GCE (Nafion/Qu/G/GCE). The as-prepared modified electrode combining the advantages of Nafion, Qu and G was employed for the selective and sensitive detection of dopamine (DA) in the presence of ascorbic acid (AA) and uric acid (UA). Compared with GCE, Qu/GCE, G/GCE and Qu/G/GCE, the Nafion/Qu/G/GCE was more electroactive and selective for DA. Differential pulse voltammetry (DPV) was used for electrochemical detection, the separations of the oxidation peak potentials for AA-DA and DA-UA were about 304 mV and 136 mV, which allowed selectively determining DA. In phosphate buffer solution (PBS) of pH 6.8, the Nafion/Qu/G/GCE provided a detection limit of 2.31×10-8 mol/L (S/N=3) for DA. Linearity (R=0.9963) of the peak currents against the concentration of DA was found over the range of 1.0×10-7 to 1.0×10-3 mol/L. Furthermore, the modified electrode exhibited good reproducibility and stability.

Synthesis of Graphene Nanocomposites with Sandwiched Electroactive Methylene Blue for Electrochemical Application

A novel nanocomposite (MB/CRG) was fabricated by a simple and fast method. The method is as follows: graphene oxide (GO) was dispersed in methylene blue (MB), and then the MB/GO was chemically reduced to MB/chemically reduced graphene (MB/CRG) by hydrazine hydrate. MB can greatly improves the dispersity of CRG in water and at the same time, the electrochemical activity of MB/CRG nanocomposite increased. The MB/CRG nanocomposite was used to modify the glass carbon electrode (GCE), and the MB/CRG/GCE was obtained. We investigated the electrochemical behavior of uric acid, NaNO2, Quercetin and p-nitrophenol at MB/CRG/GCE and found that the modified electrode had the best catalysis towards these molecules compared with MB/GCE and CRG/GCE. The MB/CRG/GCE showed good reproducibility and stability.

Fabrication of Graphene/Carbon Nanotube Composite Modified Electrode for Selective and Sensitive Determination of Uric Acid

A novel composite was firstly synthesized by compositing graphenes (G) and carbon nanotubes (CNTs) and then a new composite modified electrode (G/CNTs/GCE) was prepared by coating the resulting composite on the surface of the glassy carbon electrode (GCE). The composite modified electrode G/CNTs/GCE showed great electrochemical activities which were studied by sensitive determining the electrochemistry behaviors of uric acid (UA). It revealed when the concentration range of UA changed from 1×10-7 mol/L to 1×10-3 mol/L, the peak currents had linear relationship with the concentration of UA in the phosphate buffer solution (PBS) which the value of pH is 7.0. And the linear equation is ip (μA) = 21.55C+28.94 (C: mmol/L), with the related coefficient 0.9964.

Sensitive Determination of Rutin Using a Nafion/PMB/Graphene Composite-Modified Glassy Electrode

A novel Nafion/PMB/G/GCE was prepared by firstly electro-polymerization of MB to G/GCE and then coating Nafion on PMB/G/GCE. The as-prepared modified electrode combining the advantages of Nafion, methylene blue and G was employed for the sensitive detection of rutin. The results showed that the peak current of rutin obtained on Nafion/PMB/G/GCE was obviously high compared to bare electrode and G/GCE. Under the optimized value of pH, which was pH 3.0, peak current of rutin had good linear relation with the scan rate. At the same time, peak current increased linearly with increasing concentration of rutin. The linear range was from 5×10-7 mol/L to 1.2×10-5 mol/L, and the detection limit was 9.5×10-8 mol/L

A Simplified Method of Synthesis and Purification of 4-Dimethylamino-N-Methyl -4-Stilbazolium Tosylate

DAST (4-dimethylamino-N-methyl-4-stilbazolium tosylate) crystal material was synthesized and purified by a relatively simple method. The synthesis process was easy to operate experimentally and the cost of raw materials can be cut down. The purification process was much easier than the previously published method. Fourier transform infrared spectrum (FTIR) was used to analyze the functional group of raw material and no extra functional groups were found. Nuclear magnetic resonance (NMR) study was performed to identify the different modes presented in the compound. The results showed that the quality of the prepared crystal raw material could meet the requirements on crystal growth. DAST crystals were grown from the synthesized raw material by slowly cooling method. The crystal structure was characterized by X-ray diffraction (XRD) study and the results showed that the crystal grown from the synthesized raw material was the same as that grown from pure DAST crystal raw material.