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Mo⁰, W⁰, Fe⁰, Ru⁰, Re⁰, and Zn⁰ nanoparticles—essentially base metals—are prepared as a general strategy by a sodium naphthalenide ([NaNaph])-driven reduction of simple metal chlorides in ethers (1,2-dimethoxyethane (DME), tetrahydrofuran (THF)). All the nanoparticles have diameters ≤10 nm, and they can be obtained either as powder samples or long-term stable suspensions. Direct follow-up reactions (e.g., Mo⁰+S₈, FeCl₃+AsCl₃, ReCl₅+MoCl₅), moreover, allow the preparation of MoS₂, FeAs₂, or Re₄Mo nanoparticles of similar size as the pristine metals (≤10 nm).

A tool-box of reactive base metals: Mo⁰, W⁰, Fe⁰, Ru⁰, Re⁰, and Zn⁰ nanoparticles are prepared with diameters less than or equal to 10 nm. The reaction involves simple metal chlorides and a straightforward liquid-phase synthesis. Subsequent transformation to metal nanoparticle compounds (MoS₂, FeAs₂, Re₄Mo) is possible as well.

The structure elucidation of the novel sulfide telluride Pb₈Sb₈S₁₅Te₅ demonstrates a new versatile procedure that exploits the synergism of electron microscopy and synchrotron diffraction methods for accurate structure analyses of side-phases in heterogeneous microcrystalline samples. Suitable crystallites of unknown compounds can be identified by transmission electron microscopy and relocated and centered in a microfocused synchrotron beam by means of X-ray fluorescence scans. The refined structure model is then confirmed by simulating HRTEM images of the same crystallite. Pb₈Sb₈S₁₅Te₅ consists of chains of heterocubane-like units. Cation coordination polyhedra form unusually entwined chains of edge- and face-sharing bicapped trigonal prisms. The structure data are precise enough for bond-valence calculations, which confirm the disordered atom distribution. On this basis, optimization of physical properties becomes feasible.

Treasure quest: The complementary use of electron diffraction and microfocused synchrotron radiation enables innovative and accurate structure analyses of novel compounds in heterogeneous microcrystalline materials. The sulfide telluride Pb₈Sb₈S₁₅Te₅ was discovered this way. It adopts an unusual tetragonal structure type with building blocks that resemble NaCl-type fragments as well as chain-like units typical for sulfides.

The bottleneck in water electrolysis lies in the kinetically sluggish oxygen evolution reaction (OER). Herein, conceptually new metallic non-metal atomic layers are proposed to overcome this drawback. Metallic single-unit-cell CoSe₂ sheets with an orthorhombic phase are synthesized by thermally exfoliating a lamellar CoSe₂-DETA hybrid. The metallic character of orthorhombic CoSe₂ atomic layers, verified by DFT calculations and temperature-dependent resistivities, allows fast oxygen evolution kinetics with a lowered overpotential of 0.27 V. The single-unit-cell thickness means 66.7 % of the Co²⁺ ions are exposed on the surface and serve as the catalytically active sites. The lowered Co²⁺ coordination number down to 1.3 and 2.6, gives a lower Tafel slope of 64 mV dec⁻¹ and higher turnover frequency of 745 h⁻¹. Thus, the single-unit-cell CoSe₂ sheets have around 2 and 4.5 times higher catalytic activity compared with the lamellar CoSe₂-DETA hybrid and bulk CoSe₂.

The shape of thins to come: Atomic layers bring better catalytic properties as shown by thermally exfoliating a lamellar CoSe₂-DETA hybrid to give single-unit-cell orthorhombic CoSe₂ sheets. The single-unit-cell thickness means that 66.7 % of the Co²⁺ ions are exposed on the surface and are low coordinate leading to a lower Tafel slope and higher turnover frequency in water splitting.

FeS₂-sensitized ZnO@ZnS nanorod arrays are fabricated by a two-step solution immersion and a subsequent sulfurization. The material properties including structure, morphology, and photoluminescence are investigated by a variety of characterization methods. As compared with ZnO@ZnS core/shell structure, FeS₂-sensitized ZnO@ZnS nanorod arrays show improved optical absorption property with the extension of the absorption edge into the range of visible light. The photoresponse performance of FeS₂-sensitized Zno@ZnS is also enhanced as the photocurrent density at 1.0 V is dozens of times larger than that of ZnO@ZnS nanorods. The cause for the difference in such material properties of these two materials is discussed. In this work, a new method for sensitizing wide bandgap ZnO@ZnS nanorod arrays with improved light response performance is presented.

FeS₂-sensitized ZnO@ZnS nanorod arrays are prepared from ZnO nanorods via a two-step procedure. Enhanced photoresponse performances are observed after FeS₂ sensitization. It is ascribed to the excellent optical absorption of pyrite FeS₂ and suitable heterostructures among the three components after energy level redistribution. The transport and separation of photogenerated carriers are efficiently improved in the ternary composite system.

Many studies focus on nanoparticles as lubricity additives but overlook the fact that wear produces nanosized debris during the field use. In order to simulate the fine metal contaminants, which are the most widespread in various field applications, prefabricated Fe, Cu and Zn nanoparticles were used. Their 0.01–1% suspensions in vegetable and mineral oils with or without ZDDP and ashless AW package were tested on four-ball AW under 150-N load. Tribological effects of nanoparticles were not significant in formulations without AW additives. However, nanoFe addition produced notable lubricity improvement in already excellently performing rapeseed formulation with ZDDP, while such addition reduced performance of the ashless AW pack. Results show that metal nanoparticles can play both positive and negative roles on additive effectiveness and nanosized contaminants can significantly affect the lubricant performance. Copyright © 2015 John Wiley & Sons, Ltd.

Two-inch-sized perovskite crystals, CH₃NH₃PbX₃ (X=I, Br, Cl), with high crystalline quality are prepared by a solution-grown strategy. The availability of large perovskite crystals is expected to transform its broad applications in photovoltaics, optoelectronics, lasers, photodetectors, LEDs, etc., just as crystalline silicon has done in revolutionizing the modern electronics and photovoltaic industries.

Organic–inorganic lead halide perovskite solar cells are promising alternatives to silicon-based cells due to their low material costs and high photovoltaic performance. In this work, thin continuous perovskite films are combined with copper(I) iodide (CuI) as inorganic hole-conducting material to form a planar device architecture. A maximum conversion efficiency of 7.5% with an average efficiency of 5.8 ± 0.8% is achieved which, to our knowledge, is the highest reported efficiency for CuI-based devices with a planar structure. In contrast to related planar 2,2′,7,7′-tetrakis-(N,N -di-4-methoxyphenylamino)-9,9′-spirobifluorene (spiro-OMeTAD)-based devices, the CuI-based devices do not show a pronounced hysteresis when tested by scanning the potential in a forward and backward direction. The strong quenching of photoluminescence (PL) signal and comparatively fast decay of open-circuit voltage demonstrates a more rapid removal of positive charge carriers from the perovskite layer when in contact with CuI compared to spiro-OMeTAD. A slow response on a timescale of 10–100 s is observed for the spiro-OMeTAD-based devices. In comparison, the CuI-based device displays a significantly faster response as determined through electrochemical impedance spectroscopy (EIS) and open-circuit voltage decays (OCVDs). The characteristically slow kinetics measured through EIS and OCVD are linked directly to the current–voltage hysteresis.

Planar perovskite/copper(I) iodide solar cells with near to no J–V hysteresis, made by employing thin CuI and perovskite layers, result in a record conversion efficiency of 7.5%. The magnitude of dielectric polarization at the perovskite/hole-conductor interface is proposed to influence the degree of J–V hysteresis.

In nature, biological creatures (including plants and animals) have self-cleaning capability despite the vagaries of the environment, i.e., from sky to land, and then to marine and vagaries of foulants (non-living and living). Gecko's feet have the general self-cleaning property both in air and underwater so as to keep their feet all clean for traveling through changing their adhesion. The present work reports Gecko's fibrillar structures to demonstrate general antifouling property in air through hydrophobicity and underwater after modification with hydrophilic polymer brushes. Fibrillar polypropylene (PP) nanoarrays are fabricated by hot embossing, exhibiting superhydrophobic antifouling in air. By grafting hydrophilic polyelectrolyte brushes (PSPMA) via surface-initiated atom transfer radical polymerization, they show superoleophobic antifouling of oil droplet and algae adhesion underwater. The effect of the structure of PP nanofiber arrays on the wettability and adhesion behavior is evaluated in detail. The results provide an important scientific principle for fabricating self-cleaning low-fouling materials with micro/nanostructure, with the hydrophobic ones being more applicable in air and the hydrophilic ones well suited underwater.

Gecko's feet-like ordered polypropylene (PP) fibrillar arrays with different geometry morphologies in air are engineered, showing excellent liquid-repellent behavior toward water, juice, coffee, milk, and blood. By mimicking the low fouling fish skin, polyelectrolyte brushes (PSPMA) are decorated on the PP arrays. The as-prepared composite arrays show superoleophobicity and low cell fouling compared to the undecorated ones.

This materials-by-design approach combines nanocrystal assembly with pressure processing to drive the attachment and coalescence of PbS nanocubes along directed crystallographic dimensions to form a large 3D porous architecture. This quenchable and strained mesostructure holds the storage of large internal stress, which stabilizes the high-pressure PbS phase in atmospheric conditions. Nanocube fusion enhances the structural stability; the large surface area maintains the size-dependent properties.

Single-crystalline grains and grain boundaries in an as-grown molybdenum disulfide monolayer are visualized by second-harmonic-generation microscopy. Further statistical analysis reveals that the boundary formation is driven by kinetics, rather than energetics. The method and derived growth mechanism described on page 4069 by S. W. Wu and co-workers can be extended to many other 2D materials and help guide the tailoring or utilization of grain boundaries.