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CeO₂-TiO₂ is an important mixed oxide due to its catalytic properties, particularly in heterogeneous photocatalysis. This study presents a straightforward method to obtain 1D TiO₂ nanostructures decorated with CeO₂ nanoparticles at the surface. As the precursor, we used H₂Ti₃O₇ nanoribbons prepared from sodium titanate nanoribbons by ion exchange. Two cerium sources with an oxidation state of +3 and +4 were used to obtain mixed oxides. HAADF–STEM mapping of the Ce⁴⁺-modified nanoribbons revealed a thin continuous layer at the surface of the H₂Ti₃O₇ nanoribbons, while Ce³⁺ cerium ions intercalated partially between the titanate layers. The phase composition and morphology changes were monitored during calcination between 620 °C and 960 °C. Thermal treatment led to the formation of CeO₂ nanoparticles on the surface of the TiO₂ nanoribbons, whose size increased with the calcination temperature. The use of Ce⁴⁺ raised the temperature required for converting H₂Ti₃O₇ to TiO₂-B by approximately 200 °C, and the temperature for the formation of anatase. For the Ce³⁺ batch, the presence of cerium inhibited the conversion to rutile. Analysis of cerium oxidation states revealed the existence of both +4 and +3 in all calcined samples, regardless of the initial cerium oxidation state.

©2010 American Chemical Society. This work has been supported by MEC trough projects MAT2006-01259 and MAT2009-07882 and by the Slovenian Research Agency (J2-9217). P.U. and A.G. also acknowledge financial support from the European Union as a part of a Framework 6 program under a contract for an Integrated Infrastructure Initiative (reference 026019 ESTEEM)., We report on the synthesis of Cr^3^+-doped sodium titanate nanotubes and nanoribbons by a hydrothermal method. The presence of dopant ions in these nanostructures was confirmed by high angle annular dark field scanning transmission electron microscopy in combination with electron energy loss spectroscopy measurements. Luminescence properties of undoped and Cr^3^+-doped sodium titanate nanotubes and nanoribbons were investigated by cathodoluminescence in the scanning electron microscope. A broad visible band in the range 1.7−2.7 eV is observed in these nanostructures. Such emission is similar to that observed in bulk anatase TiO_2 and titanate powders, and is related to TiO_6 octahedra, which is a common feature to all the samples investigated. Near-infrared emission, sometimes attributed to Ti^3^+ interstitials, is observed in bulk powders but is absent in the titanate nanotubes and nanoribbons. Incorporation of Cr^3^+ between the titanate layers of the nanostructures is revealed by the characteristic intraionic emission line at 1.791 eV. Sodium titanate nanoribbons appear to be an effective host for optically active Cr^3^+ ions, as compared with nanotubes or bulk powder., MEC (Ministerio de Educación y Ciencia, España), Slovenian Research Agency, European Union Framework 6 Program, Integrated Infrastructure Initiative, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

Herein, we report on the successful controlled growth of edge enriched 3D assemblies of MoS2 nanosheets by adjusting the gas flow rate during atmospheric pressure CVD. The results revealed that 30 ml min(-1) was the optimal flow rate, in which the growth direction shifts from in-plane nanosheets to out-of-plane 3D assemblies of MoS2 nanosheets. It is suggested that, at this flow rate, we have an ideal tradeoff between the surface interaction and the mass transport of precursor molecules. Morphological, structural and chemical composition analyses showed the formation of vertically oriented MoS2 nanosheets with MoO3-x impurities, resulting from the incomplete sulfurization during the synthesis. Based on the morphological evolution of the studied material, the growth mechanism was explored. The gas sensing properties of the as grown films were tested against NH3 and NO2. They exhibited stable and reproducible responses with excellent sensitivity to ppm-level NH3 (20% response to 2 ppm) and ppb-level NO2 (11% response to 20 ppb). Additionally, this nanomaterial showed dual selectivity towards NH3 at room temperature and NO2 at 100 degrees C. To the best of our knowledge, none of the reported studies on MoS2 based gas sensors have described this dual selectivity. The experimental detection limit was below 2 ppm for NH3 while it was below 20 ppb for NO2. Besides, the vertical growth of edge enriched MoS2 bestows the sensors with notable resilience against high levels of ambient humidity. The sensor response was only slightly increased (R = 70%) in a humid environment compared to a dry background (R = 65%) when measuring 800 ppb of NO2. Therefore, this paper shows for the first time that by adjusting the flow rate it is possible to tune the morphology of AP-CVD grown MoS2 for

The outstanding versatility of graphene for surface functionalization has been exploited by its decoration with synthesized polypyrrole (PPy) nanoparticles (NPs). A green, facile, and easily scalable for mass production nanocomposite development was proposed, and the resulting PPy@Graphene was implemented in chemoresistive gas sensors able to detect trace levels of ammonia (NH3) under room-temperature conditions. Gas exposure for 5 min revealed that the presence of nanoparticles decorating graphene entail greater sensitivity (13-fold) in comparison to the bare graphene performance. Noteworthy, excellent repeatability (0.7% of relative error) and a low limit of detection of 491 ppb were obtained, together with excellent long-term stability. Besides, an extensive material characterization was conducted, and vibration bands obtained via Raman spectroscopy confirmed the formation of PPy NPs, while X-ray spectroscopy (XPS) revealed the relative abundance of the different species, as polarons and bipolarons. Additionally, XPS analyses were conducted before and after NH3 exposure to assess the PPy aging and the changes induced in their physicochemical and electronic properties. Specifically, the gas sensor was tested during a 5-month period, demonstrating significant stability over time, since just a slight decrease (11%) in the responses was registered. In summary, the present work reports for the first time the use of PPy NPs decorating graphene for gas-sensing purposes, revealing promising properties for the development of unattended gas-sensing networks for monitoring air quality.

Herein, we report for the first time on the fabrication of a hybrid material consisting of Cu2O nanoparticles-decorated multilayered tungsten disulfide nanostructures and demonstrate their remarkable gas sensing characteristics towards hydrogen sulfide gas. In the first step, a continuous film of WS2 was deposited directly on commercial alumina substrate by adopting a facile route combining aerosol-assisted chemical vapor deposition with H-2 free atmospheric pressure CVD technique. For functionalization an additional step of synthesis was added where copper oxide nanoparticles were grown and deposited directly over as-grown tungsten disulfide at low temperature (i.e., 150 degrees C) using a simple and cost-effective technique. The morphological, structural and chemical characteristics were investigated using FESEM, TEM, and EDX spectroscopy. The gas-sensing studies performed shows that this hybrid nanomaterial has excellent sensitivity towards hydrogen sulfide (11-times increase in response compared to that of pristine WS2 sensor) at moderate temperature (150 degrees C). Additionally, functionalization of pristine WS2 sensor with Cu2O nanoparticles further enhances the gas sensing performance towards the targeted gas even at room temperature (13-times increase in response compared with that of pristine WS2 sensor). Moreover, results obtained from humidity cross-sensitivity of Cu2O-WS2 sensor indicates superior gas sensing response (with a negligible decrease in response) as compared to pristine WS2 sensor, when ambient humidity is increased to 50%, which is rarely found in metal oxide-based sensors. This study could add a significant research value in the gas sensor domain.

On a daily basis, people are exposed to a multitude of health-hazardous airborne particulate matter with notable deposition in the fragile alveolar region of the lungs. Hence, there is a great need for identification and prediction of material-associated diseases, currently hindered due to the lack of in-depth understanding of causal relationships, in particular between acute exposures and chronic symptoms. By applying advanced microscopies and omics to in vitro and in vivo systems, together with in silico molecular modeling, it is determined herein that the long-lasting response to a single exposure can originate from the interplay between the newly discovered nanomaterial quarantining and nanomaterial cycling between different lung cell types. This new insight finally allows prediction of the spectrum of lung inflammation associated with materials of interest using only in vitro measurements and in silico modeling, potentially relating outcomes to material properties for a large number of materials, and thus boosting safe-by-design-based material development. Because of its profound implications for animal-free predictive toxicology, this work paves the way to a more efficient and hazard-free introduction of numerous new advanced materials into our lives.

Nanomaterial (NM) characteristics may affect the pulmonary toxicity and inflammatory response, including specific surface area, size, shape, crystal phase or other surface characteristics. Grouping of TiO2 in hazard assessment might be challenging because of variation in physicochemical properties. We exposed C57BL/6 J mice to a single dose of four anatase TiO2 NMs with various sizes and shapes by intratracheal instillation and assessed the pulmonary toxicity 1, 3, 28, 90 or 180 days post-exposure. The quartz DQ12 was included as benchmark particle. Pulmonary responses were evaluated by histopathology, electron microscopy, bronchoalveolar lavage (BAL) fluid cell composition and acute phase response. Genotoxicity was evaluated by DNA strand break levels in BAL cells, lung and liver in the comet assay. Multiple regression analyses were applied to identify specific TiO2 NMs properties important for the pulmonary inflammation and acute phase response. The TiO2 NMs induced similar inflammatory responses when surface area was used as dose metrics, although inflammatory and acute phase response was greatest and more persistent for the TiO2 tube. Similar histopathological changes were observed for the TiO2 tube and DQ12 including pulmonary alveolar proteinosis indicating profound effects related to the tube shape. Comparison with previously published data on rutile TiO2 NMs indicated that rutile TiO2 NMs were more inflammogenic in terms of neutrophil influx than anatase TiO2 NMs when normalized to total deposited surface area. Overall, the results suggest that specific surface area, crystal phase and shape of TiO2 NMs are important predictors for the observed pulmonary effects of TiO2 NMs.