Organic functionalization of graphene is successfully performed via 1,3-dipolar cycloaddition of azomethine ylide in the liquid phase. The comparison between 1-methyl-2-pyrrolidinone and N,N-dimethylformamide as dispersant solvents, and between sonication and...

An effort to synthesize Cu(I)-variant of a leadfree double perovskite isostructural with Cs2AgInCl6 resulted in the formation of Cs3Cu4In2Cl13 nanocrystals with an unusual structure, as revealed by singlenanocrystal 3D electron diffraction. These nanocrystals adopt a A2BX6 structure (K2PtCl6-type, referred to as vacancy ordered perovskite) with tetrahedrallycoordinated Cu(I) ions. In the structure, 25% of the A sites are occupied by [Cu4Cl] 3+ clusters (75% by Cs +), and the B sites are half-occupied by In 3+. Such Cs3Cu4In2Cl13 compound prepared at the nanoscale is not known in the bulk and is an example of a multinary metal halide with inorganic cluster cations residing in A sites. The stability of the compound and a direct but parity forbidden bandgap are supported by density functional theory calculations. The existence of Cs3Cu4In2Cl13 structure demonstrates that small inorganic cluster cations can occupy A sites in multinary metal halides, paving the way for a new class of materials. ASSOCIATED CONTENT Supporting Information. Elemental analyses, XPS spectra, XRD patterns, TEM-EDS maps, dark-field STEM images, 3D ED refinement, electron diffraction patterns of a single and a twinned nanocrystal, details of Rietveld refinement (PDF). Crystal structures of Cs3Cu4In2Cl13 from 3D ED and Rietveld refinement (CIF).

We report the colloidal synthesis of bismuth chalcohalide nanocrystals, which adopt a hexagonal phase that we describe with the Bi13S18X2 (in which X = Br and I) structure. Such a model structure displays columns of Bi atoms that form dimers of subvalent Bi (formally Bi2 4+), which we here ascribe to Peierls-type distortions. We suggest that the Bi2 4+ dimers are at the origin of the anomalously low band gap of this material, with the lowest energy electronic transition showing analogies with an intervalence charge transfer. Our synthetic approach and insights into the structural and electronic features of the hexagonal bismuth chalcohalides are fundamental to sustain the rapidly increasing use of this class of (nano)materials for diverse applications, such as photocatalysis and thermoelectrics.

In the field of the renewables, a large effort has been devoted in the last years to obtain conventional and new materials for solar energy conversion by using methods which couple a good efficiency and scalability with energetic and environmental concerns. This research has included the so-called kesterites, materials considered interesting for the thin-film solar cell technology, consisting of relatively abundant and harmless elements: Cu 3-x-y Fe x Zn y Sn(S,Se) 4 . In this study, we undertook the synthesis of members of the kuramite-stannite (Cu 3 SnS 4 -Cu 2 FeSnS 4 ) join by means of a two-step solvothermal approach, able to provide nanocrystalline products in an easy, low-temperature, and fast way. The sample with the highest Fe concentration was characterised by means of a multi-analytical approach, aimed to assess not only its final structural, chemical and micromorphological features, but also the redox speciation of the two transition metal cations, i.e. Cu and Fe, in relation to the overall charge balance. Namely, Electron Paramagnetic Resonance (EPR), Mössbauer and X-ray Absorption Spectroscopy (XAS) and SQUID magnetometry were involved. The main results point out an excellent control of the structural features, and an intermediate Fe content in the sample, leading to the following formula unit: Cu 2.2 Fe 0.48 Sn 1.2 S 4 . The overall findings of the multi-analytical characterization imply a complex redox balance, where inferring the site occupancy is not trivial; the charge balance, in fact, can only be achieved taking into account the presence of both Fe(III) and vacancies. Moreover, Fe is distributed over two different crystallographic sites.

the preparation of fe-decorated sporopollenins was achieved using pollen grains and an ionic liquid as solvent and functionalizing agent. the integrity of the organic capsules was ascertained through scanning electron microscopy studies. The presence of Fe in the capsule was investigated using FT-IR, X-ray photoemission spectroscopy and energy-dispersive X-ray spectroscopy. electron paramagnetic resonance and magnetization measurements allowed us to demonstrate the paramagnetic behavior of our Fe-functionalized sporopollenin. A few potential applications of pollen-based systems functionalized with magnetic metal ions via ionic liquids are discussed. Highly organized and complex 3D microstructures hold great promise for manifold applications across nanotechnologies as carriers, scavengers or catalysts, to name a few possible functional uses 1-4. Driven by these exciting prospects, great efforts have been devoted in the last few years to the preparation of polymeric microcapsules through different routes, including template-assisted methods, self-assembly of block copolymer processes, and interfacial mini-emulsion polymerization methods 5-8. However, the synthesis of such structures is generally costly and difficult, especially when obtaining microcapsule of uniform size distribution and large inner cavity is crucial. In this context, innovative strategies are progressively moving beyond artificial material synthesis and looking to nature for inspiration. In particular, scientists have started to appreciate the myriad of unique, widely available biological systems and their microscale and nanoscale architectures that might be useful for the design and fabrication of functional materials. For instance, viruses, large globular proteins like ferritin, chromatids are nanoscale structures; Larger-still microscale-structures are pollen grains. In this scenario, pollen grains represent a very promising source of 3D microstructures with desirable morphologies: they can indeed be easily sourced in large amounts from plants and can provide, through cost-effective approaches, polymeric microcapsules with a wide variety of shape and size. These features, and most importantly their consistency which is guaranteed by the species specificity, are crucial and difficult to obtain with purely synthetic materials 9-11. In pollen grains, the male partner in the reproductive process, the genetic material is protected by a double-layered wall, which consists of an inner layer (intine) and an outer layer (exine). The former is constituted mainly of cellulose, hemicellulose and pectin, whereas the latter, known as sporopollenin (SP) is composed largely of a biopolymer, whose chemical structure is still unclear, containing only carbon, hydrogen and oxygen atoms. This polymer is characterized by remarkable strength and elasticity. Furthermore, it shows an extraordinary resistance to chemical degradation or dissolution while being at the same time readily amenable to derivatization due to the presence of a network of functional groups (carbo...

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Catalysts are involved in a number of established and emerging chemical processes as well as in environmental remediation and energy conversion. Nanoparticles (NPs) can offer several advantages over some conventional catalysts, such as higher efficiency and selectivity. Nowadays, versatile and scalable nanocatalysts that combine activity and stability are still lacking. Here, we report a comprehensive investigation on the production and characterization of hybrid nano-architectures bringing a partial or total bare surface together with their catalytic efficiency evaluation on, as a proof-of-concept, the formic acid decomposition reaction. In this regard, formic acid (FA) is a convenient and safe hydrogen carrier with appealing features for mobile applications, fuel cells technologies, petrochemical processes and energetic applications. Thus, the design of robust catalysts for FA dehydrogenation is strongly demanded. Due to this, we produced and evaluated nano-architectures with various equilibrium between the size-increase of the active part and the barer catalytic surface. Overall, this work paves the way for the development of new approaches for green energy storage and safe delivery.

Hybrid improper ferroelectricity (HIF) allows the generation of an electrical polarization in the AA BB O 6 double perovskite materials thanks to the combination of two nonpolar octahedral distortions. Nevertheless, for selected combination of the A/A cations a nonpolar incommensurate phase is observed with average symmetry C2/m. Thanks to a detailed crystallographic description of the incommensurate phase, based on electron, neutron, and x-ray diffraction data, we show that the incommensurate modulation is related to an abrupt change of the out-of-phase tilting along the a and c axis, whereas the tilting along the b axis remains constant across the structure. By using group theory and symmetry analysis we show that we observe an incommensurate analog of HIF, which induces a hybrid improper dipolar density wave in NaLaCoWO 6 . The dipolar ordering is due also in this case to a trilinear invariant involving the commensurate and incommensurate octahedra tilting.