Search

Nearly monodispersed spherical silvernanoparticles (Ag NPs) weresynthesized by using tannic acid (TA) as both reductant and stabilizerin a 30 °C water bath. The size of the as-prepared Ag NPs couldbe tuned in a range of 7–66 nm by changing the molar ratioof TA to silver nitrate and pH of the reaction solutions. UV–visspectra, TEM observations, and temporal evolution of the monomer concentrationsfor the reactions carried out at different experimental conditionsshowed that the improved size distribution and size tunability ofthe Ag NPs were mainly attributed to the use of TA, which could promotethe balance of nucleation and growth processes of the NPs effectively.The size of the Ag NPs was extendable up to 200 nm in one-pot fashionby the multi-injection approach. The size-dependent surface-enhancedRaman scattering (SERS) activity of the as-prepared Ag NPs was evaluated,and the NPs with size around 100 nm were identified to show a maximumenhanced factor of 3.6 × 105. Moreover, the as-preparedTA-coated Ag NPs presented excellent colloidal stability comparedto the conventional citrate-coated ones. [ABSTRACT FROM AUTHOR]

BiFeO 3 –g-C 3 N 4 nanoscaled composite was prepared with a hydrothermal method and evaluated as a highly efficient photo-Fenton like catalyst under visible light irradiation. The BiFeO 3 –g-C 3 N 4 composite exhibited much stronger adsorption ability to lignin model pollutant (guaiacol) than that of BiFeO 3 , which may be due to the higher specific surface area (BiFeO 3 –g-C 3 N 4 : 35.59 m 2 /g > BiFeO 3 : 7.42 m 2 /g) and the adsorption form of π–π stack between g-C 3 N 4 and guaiacol. The composite exhibited excellent visible light-Fenton like catalysis activity, being influenced by the solution pH value and the proportions of BiFeO 3 and g-C 3 N 4 nanosheets. Under optimal conditions with visible light irradiation, the BiFeO 3 –g-C 3 N 4 composite yielded fast degradation of guaiacol with an apparent rate constant of 0.0452 min − 1 , which were 5.21 and 6.80 folds of that achieved by using BiFeO 3 and the mixture of BiFeO 3 and g-C 3 N 4 nanosheets, respectively. The significantly enhanced visible light-Fenton like catalytic properties of the BiFeO 3 –g-C 3 N 4 composite in comparison with that of BiFeO 3 was attributed to a large surface area, much increased adsorption capacity and the semiconductor coupling effect between BiFeO 3 and g-C 3 N 4 in the composite. [ABSTRACT FROM AUTHOR]

We report a simple but detailed solution 13 C nuclear magnetic resonance spectroscopic study of atomically precise neutral Au 25 (SR) 18 0 (SR = alkyl thiolate) clusters. The paramagnetic 13 C Knight shift of alkyl chain carbons, which is proportional to the local electron spin density, exhibits an electron spin delocalization that exponentially decays along the alkyl chain. The magnitude and decay constant of the observed electron spin delocalization, although largely independent of alkyl chain length, depend on where, that is, "in" versus "out" ( vide infra ) position, the alkyl chain is bound, in agreement with density functional theory calculations. Notably, the determined position-dependent decay constants, 1.70/Å and 0.41/Å for "in" and "out" ligands, respectively, not only could have important ramifications in molecular spintronics but are also comparable to measured decay constants in molecular electrical conductance of alkyl chains, potentially offering an alternative, simple method for estimating the latter. Moreover, the negative intercept temperatures of linear fits of reciprocal 13 C (as well its bound 1 H) Knight shift versus temperature strongly suggest the existence of local ferrimagnetism in individual Au 25 (SR) 18 0 clusters.