Synthesis of Bi<Subscript>2</Subscript>O<Subscript>4</Subscript>@TiO<Subscript>2</Subscript> Heterojunction with Enhanced Visible Light Photocatalytic Activity

A novel Bi₂O₄@TiO₂ heterojunction was constructed by a simple two-step method. The charges migration between Bi₂O₄ and TiO₂ via the heterojunction improves the electron/hole separation efficiency. Furthermore, Bi₂O₄@TiO₂ heterostructures exhibit better adsorption capability for methyl orange molecular due to their higher specific surface area than pure Bi₂O₄. As a result, Bi₂O₄@TiO₂ hybrids show an improved visible light photocatalytic activity and photostability for the degradation of methyl orange.     

A New Trinuclear Zn(II) Complex {[Zn(μ-ONN)(μ<Subscript>2</Subscript>-O)(μ-OO)]<Subscript>2</Subscript>Zn}: Synthesis,Characterization, Thermal Decomposition and Antibacterial Activity

New centrosymmetric trinuclear zinc(II) complex {[Zn(μ-ONN)(μ₂-O)(μ-OO)]₂Zn} has been synthesized by the reaction of a potentially ONN tridentate Schiff base ligand, and N,N-dimethylethylendiamin, with Zn(OAc)₂·2H₂O in methanol, in the refluxed conditions and characterized by elemental analysis, FT-IR and UV–Vis spectroscopy. Single crystal X-ray structure analysis reveals a trinuclear complex {[Zn(μ-ONN)(μ₂-O)(μ-OO)]₂Zn} with zinc(II) ions connected by three different bridges, (μ-ONN) of the Schiff base ligand, μ₂-O and μ-OO of the acetate. The complex is centrosymmetric, with one of the Zn atoms located at the inversion center. While the central Zn(II) ion is six-coordinated, the coordination number of the other Zn(II) ions is five. Finally, the {[Zn(μ-ONN)(μ₂-O)(μ-OO)]₂Zn} complex was thermally decomposed in air at 700 °C resulted in ZnO nano crystalites with the average size of 42 nm. The antibacterial activity of ligand and its zinc(II) complex were tested against gram-positive and gram-negative bacteria. The ligand showed higher activity than its zinc(II) complex.     

聚吡咯/多壁碳纳米管及其聚氨酯导电复合材料的制备和性能

以羧基化多壁碳纳米管(MWCNTs)做模版剂,采用化学氧化法将吡咯(Py)在羧基化MWCNTs表面聚合制备PPy/MWCNTs导电材料,将其添加到溶剂型聚氨酯(PU)溶液中制备了PPy/MWCNTs/PU导电复合材料,研究了Py用量对PPy/MWCNTs及其PU复合材料性能的影响.研究表明,随Py用量的增加,PPy/MWCNTs的长度不变,管径增大,sp~2和sp~3杂化C含量先提高后减少,N的掺杂梯度降低,PPy/MWCNTs的导电率高于羧基化MWCNTs和PPy.当Py用量为羧基化MWCNTs的20%时,其导电率最大.PPy/MWCNTs中N元素的掺杂程度及其管径变化是引起PPy/MWCNTs/PU复合材料的性能不同的主要原因.增加Py用量,MWCNTs中亲水的羧基因对PPy掺杂而消耗,相同导电材料用量时纳米导电粒子数目相对减少,PPy/MWCNTs/PU复合材料的耐水性能提高,定向应力、储能模量和玻璃化温度降低,导电率先增加后减小.当Py用量为羧基化MWCNTs的15%时,导电率最大.     

Enhancing effect of boron trifluoride diethyl etherate electrolytes on capacitance performance of electropolymerized poly[poly(<Emphasis Type="Italic">N</Emphasis>-vinyl-carbazole)] films

In this paper, poly[poly(N-vinyl-carbazole)] (PPVK) films electrodeposited in tetrahydrofuran (THF) containing 12 % boron trifluoride diethyl etherate (BFEE) were studied as electrode active material for supercapacitors. The morphology and thermal property were characterized by SEM, atomic force microscopy (AFM), and thermogravimetry (TG), respectively. The electrochemical capacitive behaviors of the PPVK films were also investigated by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy. The electrochemical results showed that the specific capacitance of PPVK films in CH₃CN solution was about 126 mF cm^?2 at 1.5 mA cm^?2 and the capacitance retention was only 14.4 % after 1000 cycles. It was exciting to improve the specific capacitance up to 169.3 mF cm^?2 at 1.5 mA cm^?2 and to make the cyclic stability increase to 81.8 % capacitance retention after 5000 cycles when the equivalent BFEE was added into the CH₃CN solution containing 0.05 M Bu₄NBF₄ electrolyte. These results clearly demonstrated that BFEE was an efficient promoter for the enhancement of the capacitance performance of PPVK films. Therefore, with the help of BFEE electrolyte, the PPVK films have potential application as capacitive materials in high-performance energy storage devices.     

One-pot fabrication of single-crystalline octahedral Pd-Pt nanocrystals with enhanced electrocatalytic activity for methanol oxidation

This study reports the synthesis of octahedral Pd-Pt bimetallic alloy nanocrystals through a facile, one-pot, templateless, and seedless hydrothermal method in the presence of glucose and hexadecyl trimethyl ammonium bromide. The morphologies, compositions, and structures of the Pd-Pt nanocrystals were fully characterized by various physical techniques, thereby demonstrating their highly alloying octahedral nanostructures. The formation or growth mechanism of the Pd-Pt bimetallic alloy nanocrystals was explored and is discussed here based on the experimental observations. In addition, the synthesized Pd-Pt nanocrystals were applied to the methanol oxidation reaction (MOR) in alkaline media, which proved that the as-prepared catalysts exhibit enhanced electrocatalytic activity for MOR. Pd₁Pt₃ exhibited the best stability and durability, and its mass activity was 3.4 and 5.2 times greater than those of Pt black and Pd black catalysts, respectively. The facile synthetic process and excellent catalytic performance of the as-prepared catalysts demonstrate that they have the potential to be used in direct methanol fuel cell techniques.     

Evaluation of a novel composite based on functionalized multi-walled carbon nanotube and iron phthalocyanine for electroanalytical determination of isoniazid

A novel platform for electroanalysis of isoniazid based on graphene-functionalized multi-walled carbon nanotube as support for iron phthalocyanine (FePc/f-MWCNT) has been developed. The FePc/f-MWCNT composite has been dropped on glassy carbon forming FePc/f-MWCNT/GC electrode, which is sensible for isoniazid, decreasing substantially its oxidation potential to +200 mV vs Ag/AgCl. Electrochemical and electroanalytical properties of the FePc/f-MWCNT/GC-modified electrode were investigated by cyclic voltammetry, electrochemical impedance spectroscopy, scanning electrochemical microscopy, and amperometry. The sensor presents better performance in 0.1 mol L^?1 phosphate buffer at pH 7.4. Under optimized conditions, a linear response range from 5 to 476 μmol L^?1 was obtained with a limit of detection and sensitivity of 0.56 μmol L^?1 and 0.023 μA L μmol^?1, respectively. The relative standard deviation for 10 determinations of 100 μmol L^?1 isoniazid was 2.5%. The sensor was successfully applied for isoniazid selective determination in simulated body fluids.     

High-performance supercapacitor electrode based on a nanocomposite of polyaniline and chemically exfoliated MoS<Subscript>2</Subscript> nanosheets

In this study, MoS₂ nanosheets were first prepared by exfoliating its bulk material in HCl/LiNO₃ solution with a yield of 45%, and then a facile strategy was developed to synthesize polyaniline/MoS₂ (PANI/MoS₂) nanocomposite via in situ polymerization. Structural and morphological characterizations of MoS₂ nanosheets and the nanocomposite were investigated by scanning electron microscope (SEM), transmission electron microscope (TEM), and X-ray powder diffraction. The results of SEM illustrated that orderly sawtooth polyaniline (PANI) nanoarrays were formed on the surface of MoS₂ nanosheets. The nanocomposite displayed good electrochemical performance as a supercapacitor electrode material. The specific capacitance reached 560 F/g at a current density of 1.0 A g^?1 in 1.0 M H₂SO₄ solution. Such good performance is because that the MoS₂ nanosheets provided a highly electrolytic accessible surface area for redox-active PANI and a direct path for electrons.     

Enhanced UV photosensing properties of ZnO nanowires prepared by electrodeposition and atomic layer deposition

A new process enabling the synthesis of zinc oxide (ZnO) and Al-doped ZnO nanowires (NWs) for photosensing applications is reported. By combining atomic layer deposition (ALD) for the seed layer preparation and electrodeposition for the NW growth, high-quality ZnO nanomaterials were prepared and tested as ultraviolet (UV) sensors. The obtained NWs are grown as arrays perpendicular to the substrate surface and present diameters between 70 and 130 nm depending on the Al doping, as seen from scanning electron microscopy (SEM) studies. Their hexagonal microstructure has been determined using X-ray diffraction and Raman spectroscopy. An excellent performance in UV sensing has been observed for the ZnO NWs with low Al doping, and a maximal photoresponse current of 11.1 mA has been measured. In addition, initial studies on the stability have shown that the NW photoresponse currents are stable, even after ten UV on/off cycles.     

Ultra-high surface area and mesoporous N-doped carbon derived from sheep bones with high electrocatalytic performance toward the oxygen reduction reaction

A nitrogen (N)-doped mesoporous carbon material exhibiting ultra-high surface area was successfully synthesized from sheep bones via a facile and low-cost method. The obtained carbon material had an ultra-high specific surface area of 1961 m² g^?1 and provided rich active sites for the oxygen reduction reaction (ORR), which in turn resulted in high electrocatalytic activity. It was found that the pore size distribution for the newly prepared carbonaceous material fell in the range of 1–4 nm. Benefiting from its high surface area and the presence of pyridine-N and quaternary-N species, the as-prepared carbon material exhibited excellent ORR activity in an oxygen-saturated 0.1 M KOH solution, compared to commercial Pt/C (10 wt%). Due to its high ORR catalytic activity, stability and low-cost, using sheep bone as C and N precursors to produce N-doped carbon provides an encouraging step toward the goal of replacing commercial Pt/C as fuel cell cathode electrocatalyst.     

Green fabrication of sandwich-like and dodecahedral C@Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>@C as high-performance anode for lithium-ion batteries

Sandwich-structured C@Fe₃O₄@C hybrids with Fe₃O₄ nanoparticles sandwiched between two conductive carbon layers have attracted more and more attention owing to enhanced synergistic effects for lithium-ion storage. In this work, an environment-friendly procedure is developed for the fabrication of sandwich-like C@Fe₃O₄@C dodecahedrons. Zeolitic imidazolate framework (ZIF-8)-derived carbon dodecahedrons (ZIF-C) are used as the carbon matrix, on which iron precursors are homogeneously grown with the assistance of a polyelectrolyte layer. The subsequent polydopamine (PDA) coating and calcination give rise to the formation of sandwiched ZIF-C@Fe₃O₄@C. When being evaluated as the anode material for lithium-ion batteries, the obtained hybrid manifests a high reversible capacity (1194 mAh g^?1 at 0.05 A g^?1), good high-rate behavior (796 mAh g^?1 at 10 A g^?1), and negligible capacity loss after 120 cycles.