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The development of highly luminescent water-dispersible biocompatible nanoparticles is a hot topic in biomedical research. Here, we report about the study of the energy transfer process between Tb3+ and Eu3+ in calcium fluoride nanoparticles. Water-dispersible RE-doped nanoparticles were prepared by means of a simple synthesis route without the need for high temperature, pressure or additional surface functionalization. The structural and morphological properties were investigated by means of XRPD and TEM analysis. Optical analysis led to information about both the RE ion site symmetry in the crystalline host and the Tb3+ and Eu3+ excited state lifetimes, whose remarkable duration is suitable for biosensing applications. Concerning the energy transfer process, dipole–dipole interaction, with a donor–activator critical distance of about 13 Å, was identified as the most probable mechanism. [ABSTRACT FROM AUTHOR]

Plasmonic nanostructures are intensively studied for their ability to create electromagnetic hot spots, where a great variety of optical and spectroscopic processes can be amplified. Understanding how to control the formation of hot spots in a dynamic and reversible way is crucial to further expand the panorama of plasmon enhanced phenomena. In this work, we investigate the ability to modulate the hot spots in magnetic-plasmonic iron-doped silver nanoparticles dispersed in aqueous solution, by applying an external magnetic field. Evidence of magnetic field induction of hot spots was achieved by measuring the amplification of surface enhanced Raman scattering (SERS) from analytes dispersed in the solution containing Ag-Fe NPs. A polymeric shell was introduced around Ag-Fe NPs to confer colloidal stability, and it was found that the length and density of the polymer chains have a significant influence on SERS performance, and therefore on the formation of electromagnetic hot spots, under the action of the external magnetic field. These findings are expected to provide an important contribution to understanding the growing field of tuneable electromagnetic enhancement by external stimuli, such as magnetic fields applied to magnetic-plasmonic nanoparticles., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The present study reports on the synthesis and the electrochemical behavior of Na(0.71)CoO(2), a promising candidate as cathode for Na-based batteries. The material was obtained in two different morphologies by a double-step route, which is cheap and easy to scale up: the hydrothermal synthesis to produce Co(3)O(4) with tailored and nanometric morphology, followed by the solid-state reaction with NaOH, or alternatively with Na(2)CO(3), to promote Na intercalation. Both products are highly crystalline and have the P2-Na(0.71)CoO(2) crystal phase, but differ in the respective morphologies. The material obtained from Na(2)CO(3) have a narrow particle length (edge to edge) distribution and 2D platelet morphology, while those from NaOH exhibit large microcrystals, irregular in shape, with broad particle length distribution and undefined exposed surfaces. Electrochemical analysis shows the good performances of these materials as a positive electrode for Na-ion half cells. In particular, Na(0.71)CoO(2) thin microplatelets exhibit the best behavior with stable discharge specific capacities of 120 and 80 mAh g(-1) at 5 and 40 mA g(-1), respectively, in the range 2.0-3.9 V vs. Na(+)/Na. These outstanding properties make this material a promising candidate to construct viable and high-performance Na-based batteries.

1-wt% Pd-CeO(2) catalysts were prepared by co-precipitation of Pd nanoparticles with ceria (Pd@CeO(2)-CP), by a microemulsion procedure (Pd@CeO(2)-ME), and by normal impregnation of Pd salts (Pd/CeO(2)-IMP) in order to test the concept that Pd-CeO(2) catalysts could be more stable for the water-gas-shift (WGS) reaction when the Pd is embedded in CeO(2). Initial WGS rates measured at 250 degrees C were similar for the Pd@CeO(2)-CP and Pd/CeO(2)-IMP, indicating that Pd was accessible for gas-phase reactions on both catalysts. Pd@CeO(2)-CP exhibited better stability for WGS than did Pd/CeO(2)-IMP but exposure to the WGS environment at 400 degrees C still caused a decrease in activity. Physical characterization of the Pd@CeO(2)-ME implied that the core-shell nanoparticles underwent condensation that resulted in a low surface area and poor Pd accessibility. However, the Pd@CeO(2)-ME sample exhibited good stability for WGS, suggesting that more effective encapsulation of Pd can limit the sintering of the metal phase, thus resulting in stable catalysts under high temperature reaction conditions.