A microwave-assisted strategy for synthesizing dihydrolipoic acid (DHLA) capped fluorescent gold nanoclusters (AuNCs) has been developed. Irradiation with microwaves during synthesis enhanced the fluorescence quantum yield (QY) of AuNCs by about five-fold and shortened the reaction time from hours to several minutes. The as-synthesized DHLA-AuNCs possessed bright near-infrared fluorescence (QY: 2.9%), ultrasmall hydrodynamic diameter (3.3 nm), good colloidal stability over the physiologically relevant pH range of 5-10 as well as low cytotoxicity toward HeLa cells. Moreover, these DHLA-AuNCs were capable of sensing Hg(2+) through the specific interaction between Hg(2+) and Au(+) on the surface of AuNCs; the limit of detection (LOD) was 0.5 nM. A potential application in imaging intracellular Hg(2+) in HeLa cells was demonstrated by using spinning disc confocal microscopy.

The geometric structure of MgO deposited on Fe(001) in ultrahigh vacuum by electron evaporation was determined in detail by using surface x-ray diffraction. In contrast to the common belief that MgO grows in direct contact on the Fe(001) substrate, we find an FeO interface layer between the substrate and the growing MgO structure which has not been considered thus far. This result opens new perspectives for the understanding of the Fe/MgO/Fe(001) interface and the tunneling magnetoresistance effect in general.

Carbon nanodots are known for their appealing optical properties, especially their intense fluorescence tunable in the visible range. However, they are often affected by considerable issues of optical and structural heterogeneity, which limit their optical performance and limit the practical possibility of applying these nanoparticles in several fields.Here we developed a synthesis method capable of producing a unique variety of carbon nanodots displaying an extremely high visible absorption strength (ε > 3 × 10 6 M(dot) −1 cm −1 ) and a high fluorescence quantum yield (73%). The high homogeneity of these dots reflects in many domains: morphological (narrow size distribution), structural (quasiperfect nanocrystals with large electronic bandgaps), and optical (nontunable fluorescence from a single electronic transition). Moreover, we provide the proof of principle that an aqueous solution of these dots can be used as an active medium in a laser cavity, displaying a very efficient laser emission with dye-like characteristics, which reflects the benefits of such a highly homogeneous type of carbon-based nanodots.

The hysteresis in the CO oxidation profile over Pt/Al2O3 catalysts has been intensively studied, but its origin is still controversial. In this work, the influence of the Pt particle size and size distribution was systematically investigated. By the application of conventional and advanced preparation methods, such as flame spray pyrolysis and supercritical fluid reactive deposition, a series of catalysts containing homogeneous distributions of Pt particles were obtained. An optimal Pt particle size of 2–3 nm was identified for the CO oxidation light-off on Pt/Al2O3 catalysts. The CO oxidation results show a clear correlation between the Pt nanoparticle size and the ignition/extinction profile, including the switch of the hysteresis loop. On the basis of high-angle annular dark-field scanning transmission electron microscopy characterization combined with in situ diffuse reflectance infrared Fourier transform spectroscopy and operando X-ray absorption spectroscopy measurements, the appearance of inverse hysteresis for catalysts containing very small Pt nanoparticles (<2 nm) and typical hysteresis for larger Pt nanoparticles could be related to the different CO adsorption strengthd, to surface/bulk oxidation of Pt particles, and to the ability of the catalyst to regenerate the active sites, considering also the exothermicity of the CO oxidation reaction.

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The production of upconverting nanostructures with tailored optical properties is of major technological interest, and rapid progress toward the realization of such production has been made in recent years. Ultimately, accurate understanding of nanostructure organization will lead to design rules for accurately tailoring optical properties. Here, the context of open questions still of general importance to the upconversion and nanocrystal communities is presented, with a particular emphasis on the structure–property relationships of core–shell upconverting nanocrystals. Although the optical properties of the latter have been thoroughly investigated, little is known regarding their atomic‐scale organization. Indeed, solving the atomic‐scale structure of such nanomaterials is challenging because of their intrinsic nonperiodic nature. Familiar concepts of crystallography are no longer appropriate; chemical and structural modulation waves must be introduced. To reveal the exact core–shell structures, innovative characterization techniques need to be applied and developed, as discussed herein. The continued development and application of structural characterization techniques will be vital to consolidate the currently incomplete link between atomic‐scale structure and upconversion properties. This will ultimately provide a valuable contribution to the emerging detailed guidelines on how to better design upconverting nanostructures to achieve given optical properties in terms of efficiency, absorption, spectral emission, and dynamics.

We report on nitrogen-doped carbon dots having a β-C3N4crystalline structure and yielding bright tunable fluorescence.

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