ELECTRODEPOSITION OF PLATINUM PARTICLES ON GLASSY-CARBON MODIFIED WITH COBALT PORPHYRIN AND NAFION FILM AND THEIR ELECTROCATALYTIC REDUCTION OF DIOXYGEN

In this paper, five types of chemically modified electrode (CMEs) prepared with the deposition of platinum particles on various surfaces of glassy carbon (GC) modified with cobalt porphyrin and Nafion(R) solution are characterized using the electron scanning microscope (SEM). Their activities in the four-electron reduction of dioxygen to water on the basis of their electrochemical data from cyclic voltammetric and rotating ring-disk electrode (RRDE) experiments are examined and compared. Platinum particles dispersed on the GC surface adsorbed with the cobalt porphyrin exhibit the highest activity for the electrocatalytic reduction of dioxygen. However it is interesting that the cobalt ion is lost from the center of the porphyrin ring during the preparation of the cobalt porphyrin + Nafion mixture solution, while the porphyrin ring still remains in the Nafion film, as shown by EDX analysis. The incorporation of the porphyrin may change the structure of the Nafion film into a looser form, since the platinum particles dispersed in the film are more readily exposed, resulting in more favourable mass transfer and higher activity for the electrocatalytic reduction of dioxygen.

Recovery of silver (I) using a thiourea-modified chitosan resin

This work describes the preparation of a chelating resin from chemically modified chitosan. The resin was synthesized by using O-carboxymethylated chitosan to cross-link a polymeric Schiffs base of thiourea/glutaraldehyde and characterized by IR. Batch method was applied for testing the resin's adsorption behavior. Adsorption experiments showed the resin had good adsorption capacity and high selectivity for Ag(I) in aqueous solution. The maximum uptake of Ag(I) exhibited was 3.77 mmol/g, at pH 4.0. The results also indicated that the adsorption process was exothermic and fit well with the pseudosecond-order kinetic model. Ag(I) desorption could reach 99.23% using 0.5 M thiourea-2.0 M HCl solution. (C) 2010 Elsevier B.V. All rights reserved.

Competitive protein adsorption studied with atomic force microscopy and imaging ellipsometry

The adsorption and competitive adsorption of collagen and bovine serum albumin (BSA) were directly visualized and quantified using atomic force microscopy (AFM) and imaging ellipsometry. Chemically modified silicon surfaces were used as hydrophilic and hydrophobic substrates. The results showed that collagen and BSA in single component solution adsorbed onto a hydrophobic surface two times more than that onto a hydrophilic surface. The competitive adsorption between collagen and BSA showed that serum albumin preferentially adsorbed onto a hydrophobic surface, while collagen on a hydrophilic surface. In the binary solution of BSA (1 mg/ml BSA) and collagen (0.1 mg/ml), nearly 100% of the protein adsorbed onto the hydrophobic surface was BSA, but on the hydrophilic surface only about 6% was BSA. Surface affinity was the main factor controlling the competitive adsorption.

铁氰化钴修饰电极的制备、表征及电催化性能的研究

多核过渡金属铁氰化物修饰电极的研究在电催化、电色显示器件、能量存储、离子识别等方面具有重要的意义。本文采用了电化学的循环伏安法（CV）、旋转圆盘电极技术（RDE）、傅立叶变换红外光谱法（FTIR）和扫描电子显微镜技术（SEM），系统研究了一类铁氰化物—铁氰化钴修饰玻碳（CoHCF／GC）电极的制备方法及其对神经递质多巴胺（DA）的电催化作用以及修饰溶液中一种阳离子表面活性剂十六烷基三甲基溴化铵（CTAB）的加入对所制备的CoHCF／GC电极的电化学性能和电催化性能的影响。主要内容和结论如下：1．改进了CoHCF／GC电极的制备方法。新方法具有简单易行、不受修饰物浓度干扰、修饰时间短、修饰量易于控制等优点，且制备的CoHCF粒径小、结构明确、电化学性能稳定。2．研究了CoHCF／GC电极对DA氧化的电催化性能。采用RDE测定了CoHCF／GC电极对DA的电催化氧化的动力学参数。结果表明用新方法制备的修饰电极对DA氧化有更好的电催化性能。3．研究了在修饰溶液中加入临界浓度的CTAB对所制备的CoHCF／GC电极的影响。CV的研究结果表明，CTAB的加入，基本不影响CoHCF／GC的氧化还原峰峰电位，却使其氧化还原峰峰电流明显增大，且使所制得CoHCF／GC电极对DA氧化表现出不同的电催化行为。FTIR研究表明，CTAB不吸附在电极表面，不改变COHCF膜的化学组成和结构。SEM研究结果表明，CTAB的加入使所制备的CoHCF膜长得更快，更厚，使CoHCF粒子长得更大。因此，可得出结论为CoHCF粒子的大小是影响其对DA不同的电催化行为的主要因素。4．用RDE技术测定了有、无CTAB情况下制备的CoHCF／GC电极对DA的电催化反应的动力学参数。结果表明，有CTAB时制备的CoHCF／GC电极对DA的表观动力学常数kΓ比没有时的要大。

聚吡咯膜个饰电极的研究

1）本文首次制备了掺杂六氰亚铁铜胶体微粒的聚吡咯膜修饰电极，并用XPS，SEM等手段对其进行了表征。研究了此修饰电极的电化学行为，离子选择性行为及光谱电化学行业；2）利用聚吡咯膜修饰电极成地实现了神经递质三磷酸腺苷（ATP）的电化学控制释放；3）利用计时库仑法和交流阻抗法对掺杂电活性物质的聚吡咯膜修饰电极膜内的电子传输机理进行了详细的研究；4）研究了掺杂靛红的聚吡 咯膜的电色效应现象。合成了磺化二茂铁，并成功地将其掺入PPy膜中，制成功能化的PPy膜修饰电极。

Europium complexes immobilization on titania via chemical modification of titanium alkoxide

We report a facile strategy to tether lanthanide complexes to organic-inorganic hybrid titania materials via sol-gel processing by employing chemically modified titanium alkoxide as the precursor where the organic ligand sensitizing the luminescence of lanthanide ions is bonded to titanium.

Biosorption of Cd2+, Cu2+, Ni2+ and Zn2+ ions from aqueous solutions by pretreated biomass of brown algae

In this paper, marine brown algae Laminaria japonica was chemically modified by crosslinking with epichlorohydrin (EC1 and EC2), or oxidizing by potassium permanganate (PC), or crosslinking with glutaraldehyde (GA), or only washed by distilled water (DW). They were used for equilibrium sorption uptake studies with Cd2+, Cu2+, Ni2+ and Zn2+.

Hyperbranched polymer-assisted hydrothermal in situ synthesis of submicrometer silver tubes

We produced silver tubes with an outer diameter of 1 mu m, wall thickness of 200 nm, and length of hundreds of micrometers by hydrothermal treatment of aqueous solutions of AgNO3 and hyperbranched polyglycidol (HPG) at 165 degrees C. The surfaces of the silver tubes were chemically modified by HPG, which was confirmed by FTIR of the silver tubes.

Determination of concentrated hydrogen peroxide at single-walled carbon nanohorn paste electrode

Single-walled carbon nanohorn (SWCNH) paste electrode was used for amperometric determination of concentrated hydrogen peroxide, and was compared with other carbon electrodes. The calibration plots are linear from 0.5 to 100 mM at activated SWCNH paste electrode and edge plane graphite (EPG) electrode. In contrast, the calibration plots are linear only at concentrations lower than 45 mM at graphite paste electrode, multi-walled carbon nanotube paste electrode, and glassy carbon electrode.

Amperometric glucose biosensor based on single-walled carbon nanohorns

The biosensing application of single-walled carbon nanohorns (SWCNHs) was demonstrated through fabrication of an amperometric glucose biosensor. The biosensor was constructed by encapsulating glucose oxidase in the Nafion-SWCNHs composite film. The cyclic voltammograms for glucose oxidase immobilized on the composite film displayed a pair of well-defined and nearly symmetric redox peaks with a formal potential of -0.453V. The biosensor had good electrocatalytic activity toward oxidation of glucose.

Direct electron transfer of horseradish peroxidase and its electrocatalysis based on carbon nanotube/thionine/gold composites

Horseradish peroxidase (HRP) was incorporated into multiwalled carbon nanotube/thionine/Au (MTAu) composite film by electrostatic interactions between positively charged HRP and negatively charged MTAu composite. The results of electrochemical impedance spectroscopy (EIS) confirmed adsorption of HRP on the surface of MTAu modified GC electrode.

Preparation of Prussian blue@Pt nanoparticles/carbon nanotubes composite material for efficient determination of H2O2

In this study, the fabrication of an efficient amperometric hydrogen peroxide sensor with favorable properties is presented. Prussian blue (PB) was catalytically synthesized by Pt nanoparticles (Pt-nano) from ferric ferricyanide aqueous solution to form PB@Pt-nano hybrid, and it was confirmed by transmission electron microscope (TEM) and optical spectra. The electrochemical behavior of PB@Pt-nano was highly improved through its integration with poly(diallyldimethylammonium chloride) modified carbon nanotubes (PCNTs).

Biosorption of Cd2+, Cu2+, Ni2+ and Zn2+ ions from aqueous solutions by pretreated biomass of brown algae

In this paper, marine brown algae Laminaria japonica was chemically modified by crosslinking with epichlorohydrin (EC1 and EC2), or oxidizing by potassium permanganate (PC), or crosslinking with glutaraldehyde (GA), or only washed by distilled water (DW). They were used for equilibrium sorption uptake studies with Cd2+, Cu2+, Ni2+ and Zn2+. The experimental data have been analyzed using Langmuir, Freundlich and Redlich-Peterson isotherms. The results showed that the biosorption equilibrium was well described by both the Langmuir and Redlich-Peterson isotherms.

Single-walled carbon nanohorn as new solid-phase extraction adsorbent for determination of 4-nitrophenol in water sample

Single-walled carbon nanohorn (SWCNH) was developed as new adsorbent for solid-phase extraction using 4-nitrophenol as representative. The unique exoteric structures and high surface area of SWCNH allow extracting a large amount of 4-nitrophenol over a short time. Highly sensitive determination of 4-nitrophenol was achieved by linear sweep voltammetry after only 120 s extraction. The calibration plot for 4-nitrophenol determination is linear in the range of 5.0 x 10(-8) M-1.0 x 10(-5) M under optimum conditions. The detection limit is 1.1 x 10(-8) M. The proposed method was successfully employed to determine 4-nitrophenol in lake water samples, and the recoveries of the spiked 4-nitrophenol were excellent (92-106%).