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Two synthetic projects were designed to prepare AgxAuy/Fe3O4 composite microspheres and nanoparticles via one-step hydrothermal method. The as-prepared samples were characterized by using XRD, XPS, TEM and SEM techniques, respectively. The AgxAuy/Fe3O4 composite microspheres had the uniform size with 110 nm or so. The size of AgxAuy/Fe3O4 composite nanoparticles was not uniform and Ag and Au nanoparticles were dispersed in Fe3O4. The AgxAuy/Fe3O4 composite microspheres and nanoparticles were modified on glassy carbon electrodes and their electrocatalytic performances for p-nitrophenol reduction in a base medium were investigated. The results show that Fe3O4 microspheres and nanoparticles mingled with Au showed higher electrocatalytic activity than the pure Fe3O4. As Fe3O4 was loaded with Ag and Au, the electrocatalytic activity of AgxAuy/Fe3O4 composite microspheres increased first then decreased with increasing Ag content, but the activity of AgxAuy/Fe3O4 composite nanoparticles increased with increasing Ag content. [ABSTRACT FROM AUTHOR]

Using an electrochemical polymerization process, a copper hexacyanoferrate/ordered mesoporous carbon-modified glassy carbon electrode (CuHCF/OMC/GCE) was prepared. The performance of CuHCF/OMC was compared with that of CuHCF and the properties of the new material were improved. A sensor for sensitive detection of captopril was developed based on CuHCF/OMC-modified glassy carbon electrode. The composition and morphology of the as-prepared CuHCF/OMC products were characterized by energy-dispersive X-ray spectroscopy and scanning electron microscopy. The electrochemical behaviour and electrocatalytic performance of the CuHCF/OMC-modified glassy carbon electrode towards the oxidation of captopril were evaluated by cyclic voltammetry. Results showed that the CuHCF/OMC-modified electrode exhibits two well-defined redox peaks. The linear range for the detection of captopril was from 1.0 x 10[sup -5] to 2.7 x 10[sup -3] M, with a correlation coefficient of 0.999, and the detection limit was 1.2 x 10[sup -6] M based on a signal-to-noise ratio of 3. [ABSTRACT FROM AUTHOR]

A new kind of electrode modified by depositing nickel hexacyanoferrate (NiHCF) and reduced graphene oxide (RGO) onto the surface of a glassy carbon electrode is proposed. Electrochemical property investigation demonstrated NiHCF nanoparticles formed on the surface of RGO retain their excellent electrochemical activity and the RGO can enhance the electron transfer between NiHCF nanoparticles and the glassy carbon electrode owing to the large surface of the RGO. The morphology of the NiHCF/RGO film was characterized by scanning electron microscopy. The electrochemical behaviour and electrocatalytic performance of the NiHCF/RGO glassy carbon electrode towards the oxidation of glucose were evaluated by cyclic voltammograms. Results showed that the NiHCF/RGO-modified electrode exhibits a pair of well-defined redox peaks. The linear range for the detection of glucose was 1.0 x 10[sup -6] to 1.7 x 10[sup -2]] M and the detection limit was as low as 2.8 x 10[sup -7] M based on a signal-to-noise ratio of 3. The as-made sensor was applied to determine glucose levels in human blood serum with satisfactory results. In addition, the effects of common interfering species, including ascorbic acid, uric acid, dopamine, and some carbohydrates are discussed in detail. [ABSTRACT FROM AUTHOR]

A series of CuFeO nanoparticles was synthesized with the assistance of organic amines or inorganic bases via a hydrothermal method. The prepared samples were confirmed as a spinel-type structure by x-ray diffraction. The shapes of the samples were detected by transmission electron microscope (TEM), which confirmed that all the synthesized samples were nanoparticles. The electrocatalytic properties of the samples modified on a glassy carbon electrode were investigated for the reduction of p-nitrophenol, potassium chromate (KCrO), and sodium nitrite (NaNO) in basic solution using the cyclic voltammetry method. The results showed that all the samples showed enhanced catalytic activity for the reduction of p-nitrophenol, KCrO, and NaNO. Among the samples, CuFeO prepared with cyclohexylamine (S-2) showed the highest catalytic activity for p-nitrophenol reduction, whereas CuFeO prepared with NaOH and PVP (S-4) showed the highest activity for both KCrO and NaNO reduction in basic solution. [ABSTRACT FROM AUTHOR]

Spinel-structured M3O4 (M=Fe, Co) samples with different shapes were synthesised mainly via a hydrothermal procedure. All Fe3O4 samples were prepared using a one-step process; however, all Co3O4 samples were synthesised via two-step paths, namely their precursors were prepared first then the resultant oxide products were obtained by calcining their precursors at a certain temperature. The samples were characterised by thermogravimetric analysis, X-ray diffraction, transmission electron microscopy, high-resolution electron microscopy and field-emission scanning electron microscopy measurements, respectively. The results showed that plate-, particle- and sphere-like Fe3O4 and sheet-, particle- and tube-like Co3O4 samples were obtained successfully. The electrocatalytic properties of the samples modified on a glassy carbon electrode were investigated, and the results indicated that Fe3O4 and Co3O4 samples with different shapes exhibited different enhanced electrocatalytic activity for p-nitrophenol reduction, and Fe3O4 and Co3O4 nanoparticles all showed the highest elctrocatalytic activity. [ABSTRACT FROM AUTHOR]

Abstract: One-step reaction was designed to synthesize mono-dispersed Ag/Fe3O4 micro-sphere with different Ag content via a facile and easily controlled hydrothermal method without use of any surfactant. The phases and composition analysis of the as-prepared samples were characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. The morphology of the samples was observed by transmission electron microscopy (TEM) and field-emission scanning electron microscopy (FE-SEM). The results revealed that the Ag/Fe3O4 composite samples with different Ag content were micro-spheres with almost the identical size of 175nm or so in diameter. The electrocatalytic activity of the resultant samples modified on a glassy carbon electrode (GCE) for p-nitrophenol reduction in a basic solution was investigated. The results indicated that all the samples exhibited enhanced electrocatalytic activity for p-nitrophenol reduction, and the sample with 3% Ag exhibited the highest electrocatalytic one. [Copyright &y& Elsevier]

Abstract: An assisting template with cyclohexylamine was used to synthesize low-dimensional Co3O4, MO, M–Co (Mn and Cd) composite oxides with M/Co atomic ratio of 1:2. The as-synthesized samples were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results indicated that Co3O4 and CdO possessed sheet-like morphologies, NiO demonstrated belt-like morphology, ZnO represented rod-like shape. The morphologies of the composite M–Co oxides (M) represented rod-like shape, Ni–Co and Zn–Co oxides exhibited belt-like and sheet-like morphologies. According to phase analysis with XRD technology, M–Co (Md Zn) possessed MCo2O4 spinel structure but Cd–Co oxides revealed a hybrid structure. The electrocatalytic activity for p-nitrophenol reduction with a glassy carbon electrode modified with the as-prepared metal oxides or M–Co composite oxides was investigated in a basic solution, and the results indicated that NiO and Co3O4 showed a certain but CdO and ZnO a little electrocatalytic activity for p-nitrophenol reduction, while M–Co composite oxides all revealed high electrocatalytic activity for the reduction of p-nitrophenol. [Copyright &y& Elsevier]