The galvanic replacement reaction between Ag nanoparticles (NPs) and HAuCl 4 followed by addition of ascorbic acid led to the formation of AuNPs sharing both urchin-like and hollow structures. The AgNPs took as sacrificial templates to guide the hollow structure and the intermediates provided rough surface and active sites for the further deposition of AuNPs, which originated from the reduction of excess HAuCl 4 by ascorbic acid. These unique structured AuNPs presented excellent optical properties and great advantages in catalysis applications.
A new composite material of ultrafine Ag/PW 11 O 39 -doped AgCl nanoparticles (NPs) encapsulated in a metal-organic framework (NH 2 -MIL-101(Al)) was prepared by an incipient wetness impregnation method together with photo-reduction under UV irradiation. The as-prepared composite material (abbr. Ag/POM-AgCl@NH 2 -MIL-101(Al)) was characterized by XRD, EDX, SEM, XPS, FT-IR and diffuse reflectance spectroscopy (DRS). By virtue of the coordination interaction between the polyoxometalate (POM) unit and Ag + ion in the K 6 [α-AgPW 11 O 39 ] precursor and the confined cavity of NH 2 -MIL-101(Al), the fast reaction between Ag + and Cl − ions was depressed and the over agglomeration of crystalline AgCl was limited. When the partial Ag + ions were reduced into Ag 0 metal in the AgCl NPs under UV irradiation, the resultant ultrafine Ag/POM-AgCl nanoparticles (NPs) possess an average particle size of 3.2 nm in diameter, representing one of the currently smallest Ag/AgCl composite NPs. The catalytic activity of this material was evaluated by the catalytic reduction of 4-nitrophenol and photocatalytic degradation of Rhodamine B (RhB) under visible light irradiation. Compared with its counterparts (Ag/AgCl NPs@NH 2 -MIL-101(Al)), the introduction of POM units into the Ag/AgCl composite NPs significantly improved the photocatalytic activity for degradation of RhB under visible light irradiation. A relevant photocatalytic mechanism was proposed.
The combined toxicity of lead (Pb) and nine phenols were measured. The result indicated that the combined toxicity is not only dependent on the Pb concentrations but also on the positions of substituted groups of phenols. Quantitative structure-activity relationship equations were built from the combined toxicity and physico-chemical descriptors of phenols in the different Pb concentrations. The combined toxicity was related to water solubility and the third order molecular connectivity index ((3)X) in low Pb concentration, to solute excess molar refractivity (E) and ionization constant (pKa) in medium Pb concentration and to dipolarity/polarizability (S) in high Pb concentration.
A fast reaction between zinc acetate and hexamethylenetetramine was carried out to produce peanutshaped ZnO-Ag heterostructures in ethylene glycol/water mixed solvent using Ag nanoparticles as seeds and polyvinylpyrrolidone as surfactant. The Ag nanoparticles were well-dispersed on the ZnO particles, providing them with better photocatalytic performance in the decomposition of methylene blue than the pure ZnO. Furthermore, the introduction of a layer of polypyrrole coating on the ZnO-Ag surface enhanced the catalytic activity in two ways. On one hand, polypyrrole could protect the Ag from oxidation and being lost under both UV irradiation and visible light. On the other hand, polypyrrole could prominently increase the absorption of photons under the visible light.
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