Defect engineering operated on metal oxides by chemical and structural modifications may strongly affect properties suitable for various applications such as photoelectrochemical behaviour, charge transport and luminescence. In this work we report the tuneable optical features observed in undoped monoclinic HfO 2 nanocrystals and their dependence on the structural properties of the material at the nanoscale. Transmission electron microscopy together with X-ray diffraction and surface area measurements were used to determine the fine structural modifications, in terms of crystal growth and coalescence of crystalline domains, occurring during a calcination process in the temperature range from 400 to 1000 °C. The fit of the broad optical emission into spectral components, together with time resolved photoluminescence, allowed us to identify the dual nature of the emission at 2.5 eV, where an ultrafast defect-related intrinsic luminescence (with decay time of few ns) overlaps with a slower emission (decay of several µs) due to extrinsic Ti -impurity centres. Moreover, the evolution of intrinsic visible bands during the material transformation was monitored. The relationship between structural parameters uniquely occurring in nanosized materials and the optical properties was investigated and tentatively modelled. The blue emissions at 2.5 and 2.9 eV are clearly related to defects lying at crystal boundaries, while an unprecedented emission at 2.1 eV enables, at relatively low calcination temperatures, the white luminescence of HfO 2 under near-UV excitation.

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Amorphous cobalt silicate nanobelts@carbon composites turned out to be excellent anode materials for lithium ion batteries.

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We present the assembly of preformed antimony doped tin oxide nanobuilding blocks into centimeter sized aerogels with surface areas exceeding 340 m(2) g(-1). After calcination, the resistivity of the aerogels was decreased by 4 orders of magnitude to a few kΩ cm, with the primary conducting structures measuring only a few nanometers.

Nanoparticle-containing sprays are a critical class of consumer products, since human exposure may occur by inhalation of nanoparticles (NP) in the generated aerosols. In this work, the suspension and the released aerosol of six different commercially available consumer spray products were analyzed. Next to a broad spectrum of analytical methods for the characterization of the suspension, a standardized setup for the analysis of aerosol has been used. In addition, a new online coupling technique (SMPS-ICPMS) for the simultaneous analysis of particle size and elemental composition of aerosol particles has been applied. Results obtained with this new method were confirmed by other well-established techniques. Comparison of particles in the original suspensions and in the generated aerosol showed that during spraying single particles of size less than 20 nm had been formed, even though in none of the suspensions particles of size less than 280 nm were present (Aerosol size range scanned: 7-300 nm). Both pump sprays and propellant gas sprays were analyzed and both released particles in the nm size range. Also, both water-based and organic solvent-based sprays released NP. However, a trend was observed that spraying an aqueous suspension contained in a pump spray dispenser after drying resulted in bigger agglomerates than spraying organic suspensions in propellant gas dispensers. Keywords Nanoparticles Á Nano-spray Á spICPMS Á TEM Á SMPS Á Inhalation exposure Market surveys identified silver (Benn et al. 2010; Chen and Schluesener 2008; Kaegi et al. 2010), zinc oxide (Graf et al. 2013), titanium dioxide (Skocaj et al. 2011), carbon and silica (Zhu et al. 2010) as the species that are most frequently used as nanoparticles Electronic supplementary material The online version of this article (

SummaryA thriving field in nanotechnology is to develop synergetic functions of nanomaterials by taking full advantages of unique properties of each component. In this context, combining TiO2 nanocrystals and carbon nanotubes (CNTs) offers enhanced photosensitivity and improved photocatalytic efficiency, which is key to achieving sustainable energy and preventing environmental pollution. Hence, it has aroused a tremendous research interest. This report surveys recent research on the topic of synthesis and characterization of the CNT–TiO2 interface. In particular, atomic layer deposition (ALD) offers a good control of the size, crystallinity and morphology of TiO2 on CNTs. Analytical transmission electron microscopy (TEM) techniques such as electron energy loss spectroscopy (EELS) in scanning transmission mode provides structural, chemical and electronic information with an unprecedented spatial resolution and increasingly superior energy resolution, and hence is a necessary tool to characterize the CNT–TiO2 interface, as well as other technologically relevant CNT–metal/metal oxide material systems.

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