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Metal Cd can serve as an analogue of cocatalysts loaded on CdS to separate electrons and holes to significantly enhance the efficiency of CdS photocatalytic hydrogen production. A series of Cd/CdS photocatalysts were synthesized at various molar ratios of CdSO4 and Na2S2O3·5H2O in the presence of simulated solar irradiation. Superior photocatalytic activities relative to that of pure CdS were observed on the Cd/CdS photocatalysts. When the optimal molar ratio R of Na2S2O3·5H2O to cadmium salt is 7, it results in a high average H2-production rate of 1753 μmol h-1. Possible mechanisms for both the formation and the enhanced photocatalytic activity of Cd/CdS were proposed on the basis of theoretical speculation and experimental observations. Most of all, this work highlights that (i) Cd/CdS leads to an improvement in the photocatalytic activity for H2 generation; and (ii) adding Na2S2O3·5H2O into the solution containing cadmium ions to prepare Cd/CdS can effectively remove cadmium ions. [ABSTRACT FROM AUTHOR]

A surface engineering approach was adopted for the preparation of a core-shell structure of bimetallic PtCo nanoparticles to improve catalytic activity for methanol oxidation on a mass basis. Synthesis of core-shell Co@Pt nanocomposite catalysts with different Pt content was carried out by reducing platinum precursors using ethylene glycolcitrate (EG) in aqueous solution containing previously formed Co/C. Characterizations were carried out using transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectra (XPS) and electrochemical techniques. The synthesized core-shell Co@Pt nanocomposite catalysts showed enhanced catalytic activity in the methanol oxidation reaction. The enhancement may result from favorable strain effects related to the thickness of Pt shell formed on the non-noble metal substrate. Moreover, the electrocatalytic activity was optimized by tuning shell thickness. This result confirms that changing the Pt shell thickness has a significant effect on the catalytic activities of nonnoble core-noble shell bimetallic nanoclusters. The developed surface-modification method (i.e. by fine-tuning the thickness of Pt shell on the non-noble metal substrate) has great potential application for producing highly active electrochemical catalysts for methanol oxidation on a large scale. The work thus paves the way for further investigating the strain effect in core-shell bimetallic catalysts. [ABSTRACT FROM AUTHOR]

Catalytically active Sn/W mixed transition-metal oxides were prepared by calcination of the corresponding Sn/W hydroxide precursors at different temperatures. The obtained mixed oxides were characterized by physicochemical and spectroscopic methods. With variation of the molar ratios of Sn/W, the prepared Sn/W mixed oxide catalysts had different reaction activities. Thus, the Sn/W-2-800 oxide acted as an effective heterogeneous catalyst for the Baeyer-Villiger oxidation of ketones and the Friedel-Crafts reaction. Many ketones, as well as benzyl alcohol and acetic anhydride, were transformed into the corresponding products with high conversion and selectivity. The catalysts can be easily separated from the reaction mixtures and can be reused for at least five cycles without significant loss of activity. [ABSTRACT FROM AUTHOR]

In this work, TiO2 nanofibers (TiO2-NF) with multilevel structure and nanoparticles (TiO2-NP) were respectively prepared via templateassisted and single solvothermal methods. The degradation of methylene blue (MB) was used as the model reaction to evaluate the photocatalytic properties of these prepared materials. It was important that TiO2-NF, prepared via template-assisted solvothermal method, possessed multilevel structure. The photocatalytic results indicated that their activity order was TiO2-NF > TiO2-NP. It demonstrated that the multilevel structure of TiO2-NF played an important role for enhancing its photocatalytic activity and the enhanced property could be mainly ascribed to fast adsorption/desorption of MB molecules on its surface and high efficiency of absorbing irradiating light and the efficient electrons transfer by interparticles and interparticles to the wall of the fiber. [ABSTRACT FROM AUTHOR]

Low-molecular-weight (LMW) chitosan salicylaldehyde Schiff-base and its zinc(II) complexes were synthesized and characterized by Fourier transform-infrared (FT-IR) spectra, transmission electron microscopy (TEM), dynamic light scattering (DLS), gel permeation chromatography-multiangle laser light scattering (GPC-MALLS), and elemental analysis. The results of electrophoretic analysis suggest that the Zn complexes bound to DNA by means of electrostatic interactions and intercalation. The effect of the Zn complexes on the growth of SMMC-7721 liver cancer cells was investigated by sulforhodamine B assay in vitro. The results reveal that the growth of liver cancer cells was inhibited by LMW-chitosan and their Zn complexes. The inhibition rate of the Zn complexes was higher than that of LMW-chitosan ligand. The LMW-chitosan Schiff-base Zn complex exhibited higher anticancer activity than the LMW-chitosan Zn complex. Combining LMW-chitosan with Schiffbase and Zn improved its anticancer activity, which we ascribe to the synergistic effect between the chitosan matrix and the planar construction of the Zn complexes. [ABSTRACT FROM AUTHOR]

Composite gel spherical beads of carrageen and guar gum were prepared with a size range of 2 to 3 mm, by adding montmorillonite (MMT) as a modifier for use in immobilised cell carrier technology. The interior structure and functional groups of the beads were characterised by XRD and FT-IR and the thermal stability of the beads was measured by DSC. The swelling kinetics of the composite gel spherical beads was studied. We pilot-studied living Saccharomyces cerevisiae cell immobilization and the effect of storage time on the cells' activity. The beads thermal stability was better than those of carrageen and guar gum because of the addition of MMT. The MMT made the beads form beautiful three-dimensional reticulated structures and improved their stability. It also reduced their solidification temperature and swelling ratio. The population of Saccharomyces cerevisiae on immobilised cells was about 70% of that at the beginning and was still 107 cells/g after storage for 3 months. [ABSTRACT FROM AUTHOR]

$$\begin{array}{l}{\hbox{R}^1\hbox{R}^2\hbox{CHOH}} \\ {\hbox{RCH}_2\hbox{OH} }\end{array} \dynrightarrow{Oxone}{\hbox{CH}_3\hbox{CN/H}_2\hbox{O}, 70^{\circ}\hbox{C}} \begin{array}{l}{\hbox{R}^1\hbox{R}^2\hbox{CO}} \\ {\hbox{RCOOH}} \end{array}$$ A simple and environmentally friendly procedure for the oxidation of alcohols is presented utilizing Oxone® (2KHSO5 · KHSO4 · K2 SO4) as oxidant and polymer-supported 2-iodobenzamide as catalyst in CH3CN/H2O mixed solvents. [ABSTRACT FROM AUTHOR]

Environment-responsive hydrogels are environmentally friendly polymeric materials that rapidly respond to their environment by changing their volume or strength when the external environment, such as temperature, pH, light, and magnetism, changes. As environment-responsive hydrogels, they are uniquely flexible and sensitive, enabling them to be used in various applications, and are now at the forefront of polymer science research. Scholars have reviewed more environmentresponsive hydrogels in biomedicine, detection sensors, and drug release. We present a detailed description of the reaction mechanism and preparation process of environment-responsive hydrogels, taking temperature-responsive, pH-responsive, and light-responsive hydrogels as examples. Finally, a summary is given at the end: 1) the application of environmentally responsive hydrogels in agriculture, and 2) the problems and future trends of their application in agriculture. [ABSTRACT FROM AUTHOR]

A new, low-cost, and eco-friendly organic-inorganic composite superabsorbent was successfully synthesized in aqueous solution by polymerization xanthan gum (XG), neutralized acrylic acid (AA) and loess using ammonium persulfate (APS) as initiator and N,N-methylenebisacrylamide (MBA) as crosslinker. Structure and morphological characterizations of the composite superabsorbent were investigated by Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The loess content, pH values, surfactants, salts and temperature which could affect the swelling and water-retention capabilities of the composite superabsorbent were investigated. The composite superabsorbent exhibits excellent water absorbency (610 g/g in distilled water), pH-stability (pH 5-10), and higher swelling capacity in anionic surfactant solution; on the other hand, the composite superabsorbent can be used for removing multivalent metal ions. [ABSTRACT FROM AUTHOR]

Nitrogen-doped porous carbon is prepared by carbonizing polyaspartic acid under inertia atmosphere without template and activation. The powder X-ray diffraction, element analysis, scanning electron microscopy, and N2 adsorption-desorption tests show that the morphologies and structures of the nitrogen-doped carbon samples deeply depend on carbonization temperature. Electrochemical measurements show that the specific capacitance of the PASP700 sample obtained at 700 °C is 166.1 F g-1 at a current density of 1 A g-1, and after 5000 charge/discharge cycles it still remains 97% which exhibits an excellent cycling stability. [ABSTRACT FROM AUTHOR]

Carbon-supported, Pt partially covered, PdSn alloy nanoparticles (Pt-PdSn/C) were synthesized via a metathetical reaction of PdSn alloy nanoparticles, and a platinum precursor. The electrochemical activity was evaluated by methanol oxidation. The Pt-PdSn/C catalysts were characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and cyclic voltammograms (CV). TEM showed that Pt grows layer-by-layer on the surface of PdSn cores and the thickness of the Pt shell is 0.2 nm, about 1-2monolayers thick. Cyclic voltammetry results showed that PdSn/C nanoparticles, partially covered by Pt, have a better electrocatalystic performance than conventional PtRu/C and PtPdSn/C catalysts. Electrochemical active surface areas of the Pt-PdSn/C was 2.30 times larger than that of PtRu/C and 1.8 times higher than that of PtPdSn/C catalysts. The results showed that a metathetical reaction is an efficient way of preparing, low Pt loading, highly active electrocatalyst, for methanol oxidation, thus offering great potential for producing Pt-based electrocatalyst for direct methanol fuel cells on a large scale. [ABSTRACT FROM AUTHOR]