Suwei Yao

Antibacterial activity of anodized aluminum with deposited silver

Aluminum specimens were first anodized in a sulfuric acid bath, and then silver was electrodeposited into pores of the anodized aluminum by using alternating current. The anodized aluminum with deposited silver was tested for its antibacterial performance. The results show that the antibacterial rates of the specimens with deposited silver are above 95% against the growth of Escherichia coli, Pseudomonas aeruginosa, Streptococcus faecalis and Staphylococcus aureus. The morphology of the silver in pores of anodized aluminum was characterized by transmission electron microscopy, and the micrographs exhibited that silver was assembled in the form of nanowires with a diameter of 10 or 25 nm. The nanowires have a morphology of parallel bright stripes alternating with parallel dark stripes.

Synthesis and Electrochemical Performance of Co 3 O 4 /Graphene

Co3O4/reduced graphene oxide composites were synthesized via a simple electrochemical method from graphene oxide and Co(NO3)2·6H2O as raw materials. Co3O4 nanoparticles with sizes of around 30–50 nm were distributed on the surface of graphene nanosheets confirmed by scanning electron microscopy and transmission electron microscopy. Electrochemical properties of Co3O4/graphene composite were tested by cyclic voltammetry, galvano-static charge-discharge, and electrochemical impedance spectroscopy. The Co3O4/reduced graphene oxide composite was used as the pseudocapacitor electrode in the 2 mol/L NaOH aqueous electrolyte solution. The Co3O4/reduced graphene oxide composite electrode exhibited a specific capacitance of 357 F/g at a current density of 0.5 A/g in a three-electrode system. 72% of capacitance was retained when the current density increased to 3 A/g. The Co3O4/reduced graphene oxide composite prepared electrodes show a high rate capability and excellent long-term stability. After 1000 cycles of charge and discharge, the capacitance is still maintained 87% at a current density of 1 A/g, indicating that the composite is a promising alternative electrode material used for supercapacitors.

Corrosion behaviour of electrodeposited Ni–Sn–P alloys

Abstract Ni–Sn–P alloys with a stannous content of 2·91–4·05 wt-% and a phosphorous content of 13·54–14·56 wt-% produced as a coating on copper by constant current electrodeposition were studied, with regard to their corrosion behaviour upon immersion in 10 wt-% H2SO4 solutions. The corrosion resistance of Ni–Sn–P alloy improved with increasing stannous content. X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy confirmed the formation of Sn and P enriched layers at the alloy surface. After corrosion, a layer of passive film composed of SnO2, Ni(OH)2 and Ni3(PO4)2 was formed on the surface, which could prevent the contact between metal surface and corrosive liquid.

Template Synthesis and Characterization of Cu 2 O/TiO 2 Coaxial Nanocable for Photocatalysis

Coaxial nanocable consisted of p-type Cu2O nanowires and n-type TiO2 nanotubes arrays was prepared in the porous anodic aluminum oxide(AAO) template via the sol-gel method and subsequent electrodeposition method. X-ray diffraction analysis identified an anatase structure of the TiO2 nanotubes and cubic structure of the Cu2O nanowires. The obtained samples were also characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM) and energy dispersive X-ray spectroscopy(EDS). The diffrence of open circuit potential of the coaxial nanocable electrode was larger than that of the TiO2 nanotubes electrode under ultraviolet illumination, which means doping with Cu2O could improve the photovoltage effectively. Meanwhile, nanocable arrays exhibited a high activity for photodegrading Rhodamine B under Xe lamp irradiation and the photocatalysis degradation efficiency was up to 98.69% after degradation for 7 h. The enhanced photocatalytic activity could be attributed to the high migration efficiency of photoinduced electrons, which may suppress the charge recombination effectively.

Preparation of nanocrystalline palladium on p-Si by electroless deposition and its photo-electrochemical hydrogen evolution property

Abstract The Pd-modified p-Si electrode was prepared by means of electroless deposition. The average diameter of Pd nanoparticles was about 80 nm from SEM observations. XRD results showed that the structure of Pd coatings was nanocrystalline. The catalyzing properties of the Pd-modified p-Si electrode for hydrogen evolution under illumination and in dark were studied with the constant current polarization method. The polarization potential for hydrogen evolution reaction (HER) of the Pd/p-Si electrode under illumination was 250 mV lower than that in dark, and was 450 mV lower than that of p-Si in dark at the current density of 2.5 mA·cm−2. The results of electrochemistry impedance spectra (EIS) showed that electrochemistry HER resistance of the modified electrode under illumination decreased from 593.12 to 442.20 Ω·cm2, and the HER rate increased evidently.

Electrochemical Preparation and Characterization of [NiFe/Cu/Co/Cu]nMultilayered Nanowires

采用电沉积法,在阳极氧化铝（AAO）模板中制备了[NiFe/Cu/Co/Cu]n多层纳米线.利用扫描电子显微镜（SEM）及透射电子显微镜（TEM）对纳米多层线的表面形貌及结构进行了表征,纳米线阵列高度有序、直径均一、层状结构清晰,NiFe层厚度约40 nm,Cu层厚度约60 nm,Co层厚度约15 nm,各子层厚度可控.利用X射线能谱分析仪（EDS）对纳米多层线NiFe层的成分进行了测试,Ni,Fe的原子比为4∶1.利用X射线衍射仪（XRD）对[NiFe/Cu/Co/Cu]n纳米多层膜和多层线结构进行了测试,多层膜为面心立方（fcc）结构,多层线NiFe层为面心立方（fcc）结构,Cu层为六方密排hcp（100）,Co层为面心立方（fcc）结构.与组成、结构完全相同的多层膜相比,[NiFe/Cu/Co/Cu]n多层纳米线具有更优越的巨磁电阻性能.

Effect of heat treatment on properties of Ni–Sn–P coatings

ABSTRACT The changes of the structure, microscopic morphology of electrodeposited Ni–Sn–P alloys before and after heat treatment in nitrogen were studied by means of X-ray diffraction and scanning electron microscopy. The corrosion behaviour was analysed by electrochemical impedance spectroscopy, anodic polarisation curves and potentiostatic polarisation corrosion. The results show that as the heat-treatment temperature increase, the structure of Ni–Sn–P alloy changed from amorphous to crystalline and the corrosion resistance of which decreased correspondingly. When the heat-treatment temperature was lower than 400°C, the electrodeposited Ni–Sn–P alloys remained amorphous structure and exhibited better corrosion resistance than that of electroless Ni–P coating in acidic medium.

The synthesis and application of TiO 2 microspheres as scattering layer in dye-sensitized solar cells

Mesoporous TiO2 microspheres have been synthesized via a simple one-plot hydrothermal method and were used as the light scattering layer on top of the P25 TiO2 compact layer to form a double-layer film based photoanode for the dye-sensitized solar cell (DSSC). Characteristics and light scattering properties were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, nitrogen sorption analysis and ultraviolet–visible spectroscopy. Photovoltaic performance of the fabricated DSSC was also investigated. It showed that photoelectric conversion efficiency of the double-layer film based DSSC was increased to 5.61% compared with single P25 compact layer film based (2.67%) and single TiO2 microspheres layer film based (2.14%) DSSC. Improvement of DSSC performance can be attributed to excellent light scattering capability given by mesoporous TiO2 microspheres. Electrochemical impedance spectra analysis also proved that double-layered structure can result in prolonged exciton lifetime, improved charge collection efficiency and decreased charge recombination.