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The quasi-cubic CaCO3and CaCO3 loaded with Ag nanoparticles with different contents were prepared via a facile and easily controlled co-precipitation and hydrothermal associated method. The as-synthesized samples were characterized by using X-ray diffraction and scanning electron microscopy, respectively. In the hybrids, Ag nanoparticles were dispersed finely on the cube-shaped CaCO3. The final samples were modified directly on the glassy carbon electrode and their electrocatalytic performances for the reduction of p-nitrophenol in alkaline medium and H2O2 in neutral medium as well as the oxidation of NaNO2 in neutral medium were investigated in detail. The results indicated that the glassy carbon electrode decorated with CaCO3 exhibited a certain elctrocatlytic activity for the reduction or oxidation of the three materials. The electrocatalytic performances could be enhanced obviously by using the glassy carbon electrode modified with the Ag/CaCO3 composites because of the loading of Ag nanoparticles. With increasing Ag content, the electrocatalytic activity increased gradually. Highlights: Ag/CaCO3 composites were prepared via an easily controlled methdod. Ag nanoparticles are finely dispersed on the quasi-cube CaCO3. Ag/CaCO3 composites exhibit high electroccatalytic activity. [ABSTRACT FROM AUTHOR]

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]

ZnCo2O4 and Ag/ZnCo2O4 with different Ag contents were fabricated by calcining their precursors synthesized via a combined precipitation-hydrothermal method. The as-prepared products were characterized by TG, XRD, TEM, and FE-SEM, respectively. The resultant results exhibited that both ZnCo2O4 and Ag/ZnCo2O4 samples possessed porous and sheet-like structure. The as-synthesized samples were modified directly on the glassy carbon electrode, and their electrocatalytic performances for the reduction of p-nitrophenol in the alkaline solution were investigated. The results displayed that the electrocatalytic property of Ag/ZnCo2O4 products was higher than ZnCo2O4. Additionally, the Ag/ZnCo2O4 products with high Ag content showed higher electrocatalytic property. The photocatalytic properties of the Ag/ZnCo2O4 composite nanosheets for degrading methyl orange were investigated with assistance of H2O2 under irradiation of visible light. Ag/ZnCo2O4 composites even with a lower Ag content (2%) exhibited higher photocatalytic activity. The antibacterial activity of ZnCo2O4 and composite Ag/ZnCo2O4 nanosheets to several common Gram-positive and Gram-negative bacteria was examined. The results demonstrated that the Ag/ZnCo2O4 composites displayed excellent activity even with a lower Ag content (2%) while ZnCo2O4 exhibited weak antibacterial activity. Highlights: Ag/ZnCo2O4 nanosheets can be synthesized via an easily controlled procedure. Ag/ZnCo2O4 nanosheets with a lower Ag content exhibit higher electrocatalytic activity. Ag/ZnCo2O4 nanosheets with a lower Ag content possess higher photocatalytic performance. Ag/ZnCo2O4 nanosheets can be used antibacterial reagents and have higher antibacterial activity. [ABSTRACT FROM AUTHOR]

The precursors of NiO and Au/NiO hollow spheres with different Au contents were prepared via a solvothermal method, and the final samples were obtained by calcining each precursor at 350 °C for 3 h. The as-synthesized samples were characterized by XRD, XPS, TEM, FE-SEM and BET, respectively. The absorption performances of NiO and Au/NiO hollow spheres for p-nitrophenol were studied. The results indicate that Au/NiO hollow spheres display higher adsorption property than pure NiO, furthermore, Au/NiO sample with 3 % Au shows the highest adsorption performance. The adsorption reagent concentration on the adsorption performance was investigated by using Au/NiO with 3 % Au. The electrocatalytic properties of the final samples modified on a glassy carbon electrode for p-nitrophenol reduction in a basic solution were investigated. The results revealed that the Au/NiO hollow spheres displayed enhanced electrocatalytic activity for p-nitrophenol reduction than NiO, and the electrocatalytic activity of the Au/NiO hollow spheres increases with increasing Au content. [ABSTRACT FROM AUTHOR]

Ag/NiO composite nanosheets and empty microspheres were fabricated by calcining the precursors synthesized via hydrothermal and solvothermal procedures involved four methods. The as-prepared samples were characterized by thermogravimetric and differential thermal analysis, X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and field emission scanning electron microscopy, respectively. The electrocatalytic properties of Ag/NiO composites modified on a glassy carbon electrode for p-nitrophenol reduction were investigated. The results showed that Ag/NiO composites exhibited highly enhanced electrocatalytic activity than a bare glassy carbon electrode, for not only the peak current increased clearly but also the corresponding peak potential decreased markedly. As a comparison, two NiO samples were used and the results showed that the peak current has an increase but the peak potentials have a slight decrease by comparing to a bare glassy carbon electrode. The Ag/NiO composites have the potential application in the electrocatalysis for the reduction of nitrophenol materials. [ABSTRACT FROM AUTHOR]

Sheet-like precursors of Co 3O 4 and Ag/Co 3O 4 composites with different Ag contents were synthesized with assistance of triethylamine via a hydrothermal process. The final samples were fabricated by calcing each precursor at 400 °C. The as-prepared samples were identified and characterized by thermogravimetric analysis and differential thermal analysis, X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and field emission scanning electron microscopy, respectively. The Co 3O 4 and Ag/Co 3O 4 composite samples were used as electrocatalysts modified on a glassy carbon electrode for p-nitrophenol reduction in a basic solution. The electrocatalytic results indicated that all the samples showed enhanced electrocatalytic performance for p-nitrophenol by comparing a bare glass carbon electrode, and p-nitrophenol could be reduced by Co 3O 4 at a high peak current but a rather higher peak potential but be reduced effectively by Ag/Co 3O 4 composites at lower potential. Ag/Co 3O 4 composites with 4 % Ag displayed the highest electrocatalytic activity. [ABSTRACT FROM AUTHOR]

The precursors of CoO and Ag/CoO composites with different Ag contents were synthesized with assistance of (NH)CO via a facile hydrothermal process. The final samples were fabricated by calcining each precursor at 400 °C according to TG experiment. The as-prepared samples were identified and characterized by thermogravimetric analysis, X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and field emission scanning electron microscopy, respectively. The results showed that the morphology of CoO and Ag/CoO composites were sheet-like. Ag nanoparticles were dispersed well in the nanosheets. The samples were used as electrocatalysts modified directly on a glassy carbon electrode for p-nitrophenol reduction in a basic solution. The results showed that p-nitrophenol could be reduced at a large peak current but a higher peak potential with CoO, at lower potentials with Ag/CoO composites. Ag/CoO composite with 3 % Ag showed more efficiently electrocatalytic activity than other composites. The present method suggested the potential application of Ag/CoO composites in electrocatalysis. [ABSTRACT FROM AUTHOR]

Microstructured AgWO with shuttle-like shape was synthesized via a precipitation process with assistance of Arabic gum. MWO (M=Co and Mn) nanocrystals were prepared facilely via a hydrothermal procedure. The as-prepared samples were identified and characterized by X-ray diffraction, transmission electron microscopy, and scanning electron microscopy, respectively. The resultant samples were used directly as electrocatalysts modified on a glassy carbon electrode for p-nitrophenol, KCrO and HO reduction in a basic solution. The results showed that all peak currents increased markedly but the corresponding peak potential decreased by using CoWO, MnWO and AgWO in turn by comparing to a bare glassy carbon electrode, and AgWO, CoWO and MnWO exhibited enhanced electrocatalytic activity for p-nitrophenol reduction. AgWO also showed effective electrocatalytic activity for KCrO and HO reduction, but both CoWO and MnWO almost displayed very weak electrocatalytic properties for KCrO and HO reduction in basic solution. [ABSTRACT FROM AUTHOR]

Two important iron oxides: FeO and FeO, as well as FeO and FeO nanoparticles mingling with Ag were successfully synthesized via a hydrothermal procedure. The samples were confirmed and characterized by X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The morphology of the samples was observed by transmission electron microscopy (TEM). The results indicated FeO, FeO, Ag/FeO and Ag/FeO samples all were nanoparticles with smaller sizes. The samples were modified on a glassy carbon electrode and their elctrocatalytic properties for p-nitrophenol in a basic solution were investigated. The results revealed all the samples showed enhanced catalytic performances by comparison with a bare glassy carbon electrode. Furthermore, p-nitrophenol could be reduced at a lower peak potential or a higher peak current on a glassy carbon electrode modified with Ag/FeO or Ag/FeO composite nanoparticles. [ABSTRACT FROM AUTHOR]

In the work, several facile and easily controlled procedures were designed to successfully synthesize a few NiO samples with various morphologies, including nanosheets, nanobelts, nanoparticles and empty microspheres, via a hydrothermal method. The as-prepared samples were characterized by X-ray powder diffractometer, TEM and field emission scanning electron microscopy technologies. The results revealed that the as-synthesized NiO samples displayed expected nanosheets, nanobelts, nanoparticles and empty microspheres in shape. The electrocatalytic performance of each NiO sample modified on a glassy carbon electrode for p-nitrophenol reduction in a basic solution using cyclic voltammetry method was investigated. The results indicated that the glassy carbon electrode modified with each NiO sample showed enhanced electrocatalytic activity by comparing a bare glassy carbon electrode, and especially NiO nanopatricles and empty microsphere exhibited the higher electrocatalytic activty for p-nitrophenol reduction. [ABSTRACT FROM AUTHOR]

Several transition metal oxides, including α-FeO, FeO, CoO, NiO, CuO and ZnO, were synthesized via an easily controlled hydrothermal method at assistance of organic amine (cyclohexylamine or triethylamine). The synthesized samples were identified and characterized by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), High-resolution Electron Microscopy (HR-TEM), Field Emission Scanning Electron Microscopy (FE-SEM), N adsorption/desorption measurement. The resultant metal oxides displayed various morphologies in shape. The as-prepared samples were used as electrocatalysts (CuO was excluded) modified on a glassy carbon electrode for p-nitrophenol reduction in a basic solution. FeO and CoO samples showed higher catalytic activities. [ABSTRACT FROM AUTHOR]