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Abstract: The ESTEEM consortium of electron microscopy laboratories for materials science and solid-state physics has been created as an EU-supported delocalized infrastructure (I3) to bring together the major electron microscopy centres in Europe. Its main objectives were to develop networking, to offer transnational access to these centres with specialized and complementary techniques and skills and to upgrade in close collaboration different technical and methodological aspects such as tomography, spectroscopy, holography, detectors, and specimen holders. These efforts were aimed to strengthen the position of European microscopy and to generate new technologies potentially of high relevance in many domains identified as strategic. Following the success of the first program, ESTEEM has been reconducted in 2012 for four more years with an enlarged set of partners. [Copyright &y& Elsevier]

This review deals with the structural transitions arising in anion-deficient Mn- and Cu-based perovskites when changing the anion content. Special attention is devoted to the local structure of such materials, studied with electron diffraction and high-resolution electron microscopy. Using examples of three-dimensional or layered manganites and cuprates, it is shown that oxidation/reduction reactions in such compounds are accompanied by the formation of domain structures. Fragmentation into domains can have intrinsic reasons, related to the loss of symmetry elements due to the ordering of anion vacancies, or because of the simultaneous realization of several different anion ordering patterns with close formation energies. When extra anions are inserted at low temperatures, limited diffusion ability also results in the appearance of domains of different structures arising from a local inhomogeneity in the anion distribution. The relevance of the investigation of the local structure for a correct structure interpretation is discussed. [ABSTRACT FROM AUTHOR]

The addition of alcohol to the synthesis of a mesoporous silica material will induce a transition from hexagonal (MCM-41) to cubic (MCM-48) to a lamellar phase and finally to silica spherical particles (SSP), as the alcohol adopts the role of cosurfactant. This will evolve to a cosolvent function as the alcohol concentration is further increased. X-ray diffraction suggests that a phase regression phenomenon occurs, in contradiction with the g-value. Transmission electron microscopy reveals the structure and the microstructure of the mesoporous silica spherical particles. It is shown that the SSP consists of a core of a truncated octahedron with the MCM-48 cubic structure and radial cylindrical pores grown on the surface of the truncated octahedron. This structure model and a possible formation mechanism are discussed. [Copyright &y& Elsevier]

Transmission electron microscopy is used to evaluate different deposition techniques, which optimize the microstructure and physical properties of superconducting thin films. High-resolution electron microscopy proves that the use of an YBa[sub 2]Cu[sub 2]O[sub x] buffer layer can avoid a variable interface configuration in YBa[sub 2] Cu[sub 3]O[sub 7-δ] thin films grown on SrTiO[sub 3]. The growth can also be controlled at an atomic level by using sub-unit cell layer epitaxy, which results in films with high quality and few structural defects. Epitaxial strain in Sr[sub 0.85] La[sub 0.15] CuO[sub 2] infinite layer thin films influences the critical temperature of these films, as well as the microstructure. Compressive stress is released by a modulated or a twinned microstructure, which eliminates superconductivity. On the other hand, also tensile strain seems to lower the critical temperature of the infinite layer. [ABSTRACT FROM AUTHOR]

Oxygen loss is a serious problem of lithium‐rich layered oxide (LLO) cathodes, as the high capacity of LLO relies on reversible oxygen redox. Oxygen release can occur at the surface leading to the formation of spinel or rock salt structures. Also, the lattice oxygen will usually become unstable after long cycling, which remains a major roadblock in the application of LLO. Here, it is shown that Zr doping is an effective strategy to retain lattice oxygen in LLO due to the high affinity between Zr and O. A simple sol‐gel method is used to dope Zr4+ into the LLOs to adjust the local electronic structure and inhibit the diffusion of oxygen anions to the surface during cycling. Compared with untreated LLOs, LLO–Zr cathodes exhibit a higher cycling stability, with 94% capacity retention after 100 cycles at 0.4 C, up to 223 mAh g−1 at 1 C, and 88% capacity retention after 300 cycles. Theoretical calculations show that due to the strong Zr–O covalent bonding, the formation energy of oxygen vacancies has effectively increased and the loss of lattice oxygen under high voltage can be suppressed. This study provides a simple method for developing high‐capacity and cyclability Li‐rich cathode materials for lithium‐ion batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] Solar-light driven oxidation of benzylic alcohols over photocatalysts endows significant prospects in value-added organics evolution owing to its facile, inexpensive and sustainable process. However, the unsatisfactory performance of actual photocatalysts due to the inefficient charge separation, low photoredox potential and sluggish surface reaction impedes the practical application of this process. Herein, we developed an innovative Z-Scheme Cs 3 BiBr 9 nanoparticles@porous C 3 N 4 tubes (CBB-NP@P-tube-CN) heterojunction photocatalyst for highly selective benzyl alcohol oxidation. Such composite combining increased photo-oxidation potential, Z-Scheme charge migration route as well as the structural advantages of porous tubular C 3 N 4 ensures the accelerated mass and ions diffusion kinetics, the fast photoinduced carriers dissociation and sufficient photoredox potentials. The CBB-NP@P-tube-CN photocatalyst demonstrates an exceptional performance for selective photo-oxidation of benzylic alcohol into benzaldehyde with 19, 14 and 3 times higher benzylic alcohols conversion rate than those of C 3 N 4 nanotubes, Cs 3 Bi 2 Br 9 and Cs 3 Bi 2 Br 9 @bulk C 3 N 4 photocatalysts, respectively. This work offers a sustainable photocatalytic system based on lead-free halide perovskite toward large scale solar-light driven value-added chemicals production. [ABSTRACT FROM AUTHOR]

Mixed‐halide perovskites show promising applications in tandem solar cells owing to their adjustable bandgap. One major obstacle to their commercialization is halide phase segregation, which results in large open‐circuit voltage deficiency and J‐V hysteresis. However, the ambiguous interplay between structural origin and phase segregation often results in aimless and unspecific optimization strategies for the device's performance and stability. An atomic scale is directly figured out the abundant Ruddlesden‐Popper anti‐phase boundaries (RP‐APBs) within a CsPbIBr2 polycrystalline film and revealed that phase segregation predominantly occurs at RP‐APB‐enriched interfaces due to the defect‐mediated lattice strain. By compensating their structural lead halide, such RP‐APBs are eliminated, and the decreasing of strain can be observed, resulting in the suppression of halide phase segregation. The present work provides the deciphering to precisely regulate the perovskite atomic structure for achieving photo‐stable mixed halide wide‐bandgap perovskites of high‐efficiency tandem solar cell commercial applications. [ABSTRACT FROM AUTHOR]

Uncovering an efficient and stable photocatalytic system for seawater splitting is a highly desirable but challenging goal. Herein, Cd0.2Zn0.8S@Silicalite-1 (CZS@S-1) composites, in which CZS is embedded in the hierarchical zeolite S-1, were prepared and show remarkably high activity, stability and salt resistance in seawater. [ABSTRACT FROM AUTHOR]

Review: applications in the field of inorganic nanoparticles and interfaces; 208 refs. [ABSTRACT FROM AUTHOR]

The experimental search for magnetic monopole particles has, so far, been in vain. Nevertheless, these elusive particles of magnetic charge have fuelled a rich field of theoretical study. Here, we created an approximation of a magnetic monopole in free space at the end of a long, nanoscopically thin magnetic needle. We experimentally demonstrate that the interaction of this approximate magnetic monopole field with a beam of electrons produces an electron vortex state, as theoretically predicted for a true magnetic monopole. This fundamental quantum mechanical scattering experiment is independent of the speed of the electrons and has consequences for all situations where electrons meet such monopole magnetic fields, as, for example, in solids. The set-up not only shows an attractive way to produce electron vortex states but also provides a unique insight into monopole fields and shows that electron vortices might well occur in unexplored solid-state physics situations. [ABSTRACT FROM AUTHOR]

The 3DOM TiO 2 -Au-CdS inverse opal photonic crystal structure is designed for visible-light hydrogen production, exhibiting extremely enhanced photocatalytic activity via coupling bifunctional SPR effect and electron transfer of Au NPs with slow photon effect. [Display omitted] • The ternary TiO 2 -Au-CdS (TAC) photocatalysts have been designed to couple the bifunctional Au NPs with slow photon effect. • A two electron transfer paths model is proposed in the ternary TAC photocatalysts. • Finite-difference time-domain (FDTD) simulations are used to reveal the size effect of Au NPs. • The ternary TAC-10 photocatalyst with ~ 10 nm Au NPs demonstrates the highest hydrogen evolution rate under visible-light. Gold nanoparticles (Au NPs) with surface plasmonic resonance (SPR) effect and excellent internal electron transfer ability have widely been combined with semiconductors for photocatalysis. However, the in-depth effects of Au NPs in multicomponent photocatalysts have not been completely understood. Herein, ternary titanium oxide-gold-cadmium sulfide (TiO 2 -Au-CdS, TAC) photocatalysts, based on hierarchical TiO 2 inverse opal photonic crystal structure with different Au NPs sizes have been designed to reveal the SPR effect and internal electron transfer of Au NPs in the presence of slow photon effect. It appears that the SPR effect and internal electron transfer ability of Au NPs, depending on their sizes, play a synergistic effect on the photocatalytic enhancement. The ternary TAC-10 photocatalyst with ~ 10 nm Au NPs demonstrates an unprecedented hydrogen evolution rate of 47.6 mmolh-1g−1 under visible-light, demonstrating ~ 48% enhancement comparing to the sample without slow photon effect. In particular, a 9.83% apparent quantum yield under 450 nm monochromatic light is achieved for TAC-10. A model is proposed and finite-difference time-domain (FDTD) simulations reveal the size influence of Au NPs in ternary TAC photocatalysts. This work suggests that the rational design of bifunctional Au NPs coupling with slow photon effect could largely promote hydrogen production from visible-light driven water splitting. [ABSTRACT FROM AUTHOR]

In most semiconducting metal chalcogenides, a large deformation is usually accompanied by a phase transformation, while the deformation mechanism remains largely unexplored. Herein, a phase‐transformation‐induced deformation in Ag2Se is investigated by in situ transmission electron microscopy, and a new ordered high‐temperature phase (named as α ′‐Ag2Se) is identified. The SeSe bonds are folded when the Ag+‐ion vacancies are ordered and become stretched when these vacancies are disordered. Such a stretch/fold of the SeSe bonds enables a fast and large deformation occurring during the phase transition. Meanwhile, the different SeSe bonding states in α‐, α ′‐, β‐Ag2Se phases lead to the formation of a large number of nanoslabs and the high concentration of dislocations at the interface, which flexibly accommodate the strain caused by the phase transformation. This study reveals the atomic mechanism of the deformation in Ag2Se inorganic semiconductors during the phase transition, which also provides inspiration for understanding the phase transition process in other functional materials. [ABSTRACT FROM AUTHOR]

Highlights: [•] We review the different steps that have pushed the resolution in 3D to the atomic level. [•] A broad range of methodologies and practical examples together with their impact on materials science are discussed. [•] An outlook and future challenges in the field of high resolution electron tomography are described. [ABSTRACT FROM AUTHOR]

Abstract: Copper deposited by thermal evaporation onto pristine and oxygen plasma treated carbon nanotubes (CNTs) diffuse over the CNT surface, coalescing and forming crystalline islands. The nucleation sites of the islands are preferentially defects, and more homogeneous island dispersion was observed at the CNT oxygen functionalized surface. The presence of weakly bound oxygen atoms at the CNT surface induces the formation of Cu–O bonds at the Cu/CNT interface, as described through density functional calculations. Exposure to air allows further oxidation to facetted crystalline Cu2O. Oxygen plasma pre-treatment represents a promising route for homogenous disperse Cu2O nanoparticle decoration of CNTs. [Copyright &y& Elsevier]

Abstract: The Fe2(Sr2− x A x )FeO6.5− δ/2 systems have been investigated, by doping the iron rich 2201-type parent structure with Ba2+, La3+ and 5d10 post-transition cations. The syntheses have been carried out up to the limit of the 2201-type solid solutions, in order to test the role of the double iron layer Fe2O2.5− δ/2. The localisation of the charge carriers in these compounds is consistent with their strong antiferro-magnetism. The investigation was then carried out in the transition part of the diagram up to the formation of stable phases. The study of structural mechanisms was carried using high resolution electron microscopy (transmission and scanning transmission), electron diffraction and energy dispersive spectroscopy. Different non-stoichiometry mechanisms are observed, depending on the electronic structure and chemical properties of the doping elements. The specific behavior of the modulated double iron layer is discussed. [Copyright &y& Elsevier]

A general description and review is given of a new type of anion-deficient perovskite-based structure where the perovskite parent structure is fragmented by periodically spaced translational interfaces. These interfaces demonstrate properties similar to those of the crystallographic shear (CS) planes in the ReO3-type oxides and can be considered to be CS planes in the perovskite framework that contains cations at the A positions. The building principles and chemical compositions of such CS structures will be discussed. [ABSTRACT FROM AUTHOR]

The microstructural and compositional evolution during initial annealing of a superconducting (Bi,Pb)2Sr2Ca2Cu3O10+δ/Ag tape is studied using quantitative transmission electron microscopy. Special attention is devoted to the occurrence of Pb-rich liquids, which arc crucial for the Bi2Sr2CaCu2O8+&delta to (Bi,Pb)2Sr2Ca2Cu3O10+δ transformation, Ca and/or Pb-rich (Bi,Pb)2Sr2CaCu2O8+&delta grains dissolve into a liquid, which reacts with Ca-rich phases to increase the liquid's Ca-content. This leads to (Bi,Pb)2Sr2Ca2Cu3O10+δ formation. Apparently, a Ca/Sr ratio of around I is sufficient to keep (Bi,Pb)2Sr2Ca2Cu3O10+δ a nucleation going. It is confirmed that Ag particles are transported from the Ag-sheath into the oxide core by the liquid and not by mechanical treatment of the tape. [ABSTRACT FROM AUTHOR]

Presents a study on twins in minerals, focusing on needle and right-angled twins. Information on transformation twinning; Use of transmission electron microscopy or optical microscopy to identify twins; Experimental techniques used in the study; Comparison of theoretical ideas with experimental observations; Discussion on the results of the study.

Highlights: [•] Transmission microscopy combined with near edge X-ray absorption spectroscopy. [•] Electronic states of carbon nanohorns. [•] Influence of pentagonal carbon rings in the carbon nanohorns electronic states. [ABSTRACT FROM AUTHOR]

P–n photovoltaic junctions are essential building blocks for optoelectronic devices for energy conversion. However, this photovoltaic efficiency has almost reached its theoretical limit. Here, a brand‐new excitonic photovoltaic effect in 2D CsPbBr3/CdS heterostructures is revealed. These heterostructures, synthesized by epitaxial growth, display a clean interface and a strong interlayer coupling. The excitonic photovoltaic effect is a function of both the built‐in equilibrium electrical potential energy and the chemical potential energy, which is generated by the significant concentration gradient of electrons and holes at the heterojunction interface. Excitingly, this novel photovoltaic effect results in a large open‐circuit voltage of 0.76 V and a high power conversion efficiency of 17.5%. In addition, high photodetection performance, including a high photoswitch ratio (Ilight/Idark) of 105 and a fast response rate of 23 µs are obtained. These findings provide a new platform for photovoltaic applications. [ABSTRACT FROM AUTHOR]

Faraday rotation has been used to investigate a series of polymer films doped with magnetic iron oxide nanoparticles. The films have been prepared by spin-coating and melt-processing. In each case, upon varying the angle of optical incidence on the films, an in-plane magnetic anisotropy is observed. The effect of such an anisotropy on the Faraday rotation as a function of the angle of optical incidence is verified by comparison with magnetically poled films. These results demonstrate that care should be taken upon analyzing the magnetic behavior of such films on account of the sample preparation techniques themselves being able to affect the magnetization. [ABSTRACT FROM AUTHOR]

2D homojunctions have stimulated extensive attention because of their perfect thermal and lattice matches, as well as their tunable band structures in 2D morphology, which provide fascinating opportunities for novel electronics and optoelectronics. Recently, 2D nonlayered materials have attracted the attention of researchers owing to their superior functional applications and diverse portfolio of the 2D family. Therefore, 2D nonlayered homojunctions would open the door to a rich spectrum of exotic 2D materials. However, they are not investigated due to their extremely difficult synthesis methods. Herein, nonlayered CdSe flakes homojunctions are obtained via self‐limited growth with InCl3 as a passivation agent. Interestingly, two pieces of vertical wurtzite‐zinc blende (WZ‐ZB) homojunctions epitaxially integrate into WZ/ZB lateral junctions. These homojunctions show a divergent second‐harmonic generation intensity, strongly correlated to the multiple twinned ZB phase, as identified by aberration‐corrected scanning transmission electron microscopy and theoretical calculations. Impressively, the photodetector based on this WZ/ZB CdSe homojunction shows excellent performances, integrating a high photoswitching ratio (3.4 × 105) and photoresponsivity (3.7 × 103 A W−1), suggesting promising potential for applications in electronics and optoelectronics. [ABSTRACT FROM AUTHOR]

Structural, magnetic, and electrical properties of La0.8Sr0.2MnO3 single crystals grown by the floating zone technique have been investigated using x-ray Laue diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy and magnetic force microscopy (MFM) magnetization and resistivity measurements. The aim of this work was to identify growth defects and their possible correlation with the transport properties or magnetic self-organization. The analysis by x-ray Laue diffraction and SEM reveals large single crystal structure without any extended microdefects and with a homogeneous composition. TEM observations show nanometric defects present only in the central part of the grown rod and allow to identify these defects as nanocracks resulting from a high stress gradient during the growth. Transport measurements indicate that there is an effect of the variation of oxygen content but the conducting behavior between 300 and 5 K is not affected by the presence of the nanocracks. Moreover, the magnetic behavior of the single crystal, observed by MFM, shows that the magnetic ordering of the domains is strongly connected to the structural properties and the amount of defects. [ABSTRACT FROM AUTHOR]

Glass ceramic composites were prepared by bulk crystallization of NaNbO3 in sodium niobium borate glasses. A homogeneous bulk crystallization of the NaNbO3 phase takes place during heat treatments that produces visible-near infrared transparent materials with ∼30 nm NaNbO3 nanocrystallites. Upon thermal poling, a strong Na+ depleted nonlinear optical thin layer is observed at the anode side that should induce a large internal static electric field. In addition, the χ(2) response of the poled glass ceramic composites increases from 0.2 up to 1.9 pm/V with the rate of crystallization. Two mechanisms may be considered: a pure structural χ(2) process connected with the occurrence of a spontaneous ferroelectric polarization or an increase of the χ(3) response of the nanocrystallites that enhances the electric field induced second harmonic generation process. [ABSTRACT FROM AUTHOR]

• 3D PtCu nanospheres (NSs) are synthesized by using CuCoO nanowires as seeds and H 2 PtCl 6 as Pt source. • Owing to the oxidation-reduction potential difference between Cu and Co atoms, the 3D nanospheres structure can be obtained. • The obtained PtCu NSs with a Pt-rich surface structure exhibits a greatly high catalytic activity and durability. • DFT calculations demonstrate that downshift of the d-band center of PtCu alloy indicate an increased ORR activity of Pt. Because of high electrocatalytic activity, Pt based metal nanospheres (NSs) have attracted a lot of attention. Hence, multi-particle nano-single crystal coalesced PtCu NSs are designed and successfully synthesized by a cost-effective aqueous solution method. The formed PtCu NS catalyst exhibits a superior hydrogen evolution reaction (HER) electrocatalytic activity with an ultralow onset potential of 18 mV at the current density of 2 mA/cm2 and high mass activity of 1.08 A/mg Pt (7.2 times higher than that of commercial Pt/C catalysts). Also, it shows an enhancement of 3.2 and 2.7 times in the mass and specific activities toward oxygen reduction reaction (ORR) compared to that of Pt/C. Moreover, it possesses an excellent catalytic durability for both ORR and HER. Even after 10,000 cycles, its ORR mass activity retains 87% of its initial value. The density functional theory (DFT) calculations demonstrate that by introducing Cu atoms into the Pt lattice, a downshift of the D-band center and favorable hydrogen adsorption free energy of approaching to zero (ΔG) occur, indicating the increased electrocatalytic activity of Pt electrocatalysts. [ABSTRACT FROM AUTHOR]

Graphical abstract Ag@PdAg core-shell nanoparticles prepared by one-pot strategy exhibits excellent ethene selectivity and unexpected stability in acetylene selective hydrogenation. Highlights • Supported Ag@PdAg core-shell catalyst is synthesized by a facile one-pot method. • Shell thickness can be turned by the control of Pd precursor concentration. • A surficial electronic modification was observed over the Ag@PdAg NPs. • The Ag@PdAg catalyst exhibits excellent ethene selectivity in C 2 H 2 hydrogenation. Abstract Precise control of elemental configurations within multimetallic nanoparticles could enable access to functional nanomaterials with significant performance benefits. Here, we present a one-pot synthesis of supported Ag@PdAg core-shell catalyst with an ordered PdAg alloy shell and an Ag core. Both the relative reduction potential and ratio of metal precursors are essential for this synthesis strategy. The distinguished properties of Ag@PdAg, particularly the electronic structure, indicates the existence of electron modification not only between Pd and Ag on PdAg shell, but between Ag core and alloy shell. The Ag@PdAg catalyst displays 97% ethene yield in the partial hydrogenation of acetylene, which is 2.0 and 8.1 times that of over PdAg alloy and pure Pd catalysts, and this is the most selective catalyst reported to data under industrial evaluation conditions. Moreover, this core-shell structure exhibits preferable stability with comparison to PdAg alloy catalyst. The facile synthesis of core-shell architecture with alloy shell structure provides a new platform for efficient catalytic transfer of chemical resource. [ABSTRACT FROM AUTHOR]

Abstract: Alloyed metal nanocatalysts are of environmental and economic importance in a plethora of chemical technologies. During the catalyst lifetime, supported alloy nanoparticles undergo dynamic changes which are well‐recognized but still poorly understood. High‐temperature O2–H2 redox cycling was applied to mimic the lifetime changes in model Pt13In9 nanocatalysts, while monitoring the induced changes by in situ quick X‐ray absorption spectroscopy with one‐second resolution. The different reaction steps involved in repeated Pt13In9 segregation‐alloying are identified and kinetically characterized at the single‐cycle level. Over longer time scales, sintering phenomena are substantiated and the intraparticle structure is revealed throughout the catalyst lifetime. The in situ time‐resolved observation of the dynamic habits of alloyed nanoparticles and their kinetic description can impact catalysis and other fields involving (bi)metallic nanoalloys. [ABSTRACT FROM AUTHOR]

Abstract: Alloyed metal nanocatalysts are of environmental and economic importance in a plethora of chemical technologies. During the catalyst lifetime, supported alloy nanoparticles undergo dynamic changes which are well‐recognized but still poorly understood. High‐temperature O2–H2 redox cycling was applied to mimic the lifetime changes in model Pt13In9 nanocatalysts, while monitoring the induced changes by in situ quick X‐ray absorption spectroscopy with one‐second resolution. The different reaction steps involved in repeated Pt13In9 segregation‐alloying are identified and kinetically characterized at the single‐cycle level. Over longer time scales, sintering phenomena are substantiated and the intraparticle structure is revealed throughout the catalyst lifetime. The in situ time‐resolved observation of the dynamic habits of alloyed nanoparticles and their kinetic description can impact catalysis and other fields involving (bi)metallic nanoalloys. [ABSTRACT FROM AUTHOR]

The covalent triazine framework, CTF-1, served as host material for the in situ synthesis of Fe 2 O 3 nanoparticles. The composite material consisted of 20 ± 2 m% iron, mainly in γ -Fe 2 O 3 phase. The resulting γ -Fe 2 O 3 @CTF-1 was examined for the adsorption of As III , As V and Hg II from synthetic solutions and real surface-, ground- and wastewater. The material shows excellent removal efficiencies, independent from the presence of Ca 2+ , Mg 2+ or natural organic matter and only limited dependency on the presence of phosphate ions. Its adsorption capacity towards arsenite (198.0 mg g −1 ), arsenate (102.3 mg g −1 ) and divalent mercury (165.8 mg g −1 ) belongs amongst the best-known adsorbents, including many other iron-based materials. Regeneration of the adsorbent can be achieved for use over multiple cycles without a decrease in performance by elution at 70 °C with 0.1 M NaOH, followed by a stirring step in a 5 m% H 2 O 2 solution for As or 0.1 M thiourea and 0.001 M HCl for Hg. In highly contaminated water (100 μg L −1 ), the adsorbent polishes the water quality to well below the current WHO limits. [ABSTRACT FROM AUTHOR]

The critical current Ic(B) of YBa2Cu3O7-δ (YBCO) coated conductors can be increased by growing thicker superconductor layers as well as improving the critical current density Jc(B) by the incorporation of artificial pinning centers. We studied the properties of pulsed laser deposited BaHfO3 (BHO)-doped YBCO films with thicknesses of up to 5 μm on buffered rolling-assisted biaxially textured Ni-5 at%Wtape and alternating beam assisted deposition textured Yttrium-stabilized ZrO2 layers on stainless steel. X-Ray diffraction confirms the epitaxial growth of the superconductor on the buffered metallic template. BHO additions reduce the film porosity and lower the probability to grow misoriented grains, hence preventing the Jc decrease observed in undoped YBCO films with thicknesses >2 μm. Thereby, a continuous increase in Ic at 77 K is achieved. A mixed structure of secondary phase nanorods and platelets with different orientations increases Jc(B) in the full angular range and simultaneously lowers the Jc anisotropy compared to pristine YBCO. [ABSTRACT FROM AUTHOR]

Abstract: Highly dispersed PtPd bimetallic nanocrystals with enhanced catalytic activity and stability were prepared by adjusting the interfacial wettability of the reaction solution on a commercial carbon support. This approach holds great promise for the development of high‐performance and low‐cost catalysts for practical applications. [ABSTRACT FROM AUTHOR]

Graphene, having all atoms on its surface, is favorable to extend the functions by introducing the spin–orbit coupling and magnetism through proximity effect. Here, we report the tunable interfacial exchange field produced by proximity coupling in graphene/BiFeO3 heterostructures. The exchange field has a notable dependence with external magnetic field, and it is much larger under negative magnetic field than that under positive magnetic field. For negative external magnetic field, interfacial exchange coupling gives rise to evident spin splitting for N ≠ 0 Landau levels and a quantum Hall metal state for N = 0 Landau level. Our findings suggest graphene/BiFeO3 heterostructures are promising for spintronics. [ABSTRACT FROM AUTHOR]

In-situ fabrication of palladium(0) nanoparticles inside zeolitic imidazolate frameworks (ZIF-8) has been established via one-step facile spray-dry technique. Crystal structures and morphologies of the Pd@ZIF-8 samples are investigated by powder XRD, TEM, SAED, STEM, and EDX techniques. High angle annular dark field scanning transmission electron microscopy (HAAD-STEM) and 3D tomographic analysis confirm the presence of palladium nanoparticles inside the ZIF-8 structure. The porosity, surface area and N 2 physisorption properties are evaluated for Pd@ZIF-8 with various palladium contents. Furthermore, Pd@ZIF-8 samples are effectively applied as heterogeneous catalysts in alkenes hydrogenation. This straightforward method is able to speed up the synthesis of encapsulation of metal nanoparticles in metal organic frameworks. [ABSTRACT FROM AUTHOR]

Mesoporous MIL-101(Cr) is used as host for a ship-in-a-bottle type adsorbent for selective U(VI) recovery from aqueous environments. The acid-resistant cage-type MOF is built in-situ around N,N-Diisobutyl-2-(octylphenylphosphoryl)acetamide (CMPO), a sterically demanding ligand with high U(VI) affinity. This one-step procedure yields an adsorbent which is an ideal compromise between homogeneous and heterogeneous systems, where the ligand can act freely within the pores of MIL-101, without leaching, while the adsorbent is easy separable and reusable. The adsorbent was characterized by XRD, FTIR spectroscopy, nitrogen adsorption, XRF, ADF-STEM and EDX, to confirm and quantify the successful encapsulation of the CMPO in MIL-101, and the preservation of the host. Adsorption experiments with a central focus on U(VI) recovery were performed. Very high selectivity for U(VI) was observed, while competitive metal adsorption (rare earths, transition metals...) was almost negligible. The adsorption capacity was calculated at 5.32 mg U/g (pH 3) and 27.99 mg U/g (pH 4), by fitting equilibrium data to the Langmuir model. Adsorption kinetics correlated to the pseudo-second-order model, where more than 95% of maximum uptake is achieved within 375 min. The adsorbed U(VI) is easily recovered by desorption in 0.1 M HNO 3 . Three adsorption/desorption cycles were performed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Accurate observation of dopants in layered cathode materials at atomic scale. • Significant reference and guidance for local structure characterization of various doped layered cathode materials. • An in-depth study on the structure–property correlation of Na+-doped cathode materials via multi-scale calculations. • Extending the theoretical electrochemical model for battery investigation. The introduction of Na+ is considered as an effective way to improve the performance of Ni-rich cathode materials. However, the direct structure–property correlation for Na+ doped NCM-based cathode materials remain unclear, due to the difficulty of local and accurate structural characterization for light elements such as Li and Na. Moreover, there is the complexity of the modeling for the whole Li ion battery (LIB) system. To tackle the above-mentioned issues, we prepared Na+-doped LiNi 0.6 Co 0.2 Mn 0.2 O 2 (Na-NCM622) material. The crystal structure change and the lattice distortion with picometers precision of the Na+-doped material is revealed by Cs-corrected scanning transmission electron microscopy (STEM). Density functional theory (DFT) and the recently proposed electrochemical model, i.e., modified Planck-Nernst-Poisson coupled Frumkin-Butler-Volmer (MPNP-FBV), has been applied to reveal correlations between the activation energy and the charge transfer resistance at multiscale. It is shown that Na+ doping can reduce the activation energy barrier from ΔG = 1.10 eV to 1.05 eV, resulting in a reduction of the interfacial resistance from 297 Ω to 134 Ω. Consequently, the Na-NCM622 cathode delivers a superior capacity retention of 90.8 % (159 mAh.g−1) after 100 cycles compared to the pristine NCM622 (67.5 %, 108 mAh. g−1). Our results demonstrate that the kinetics of Li+ diffusion and the electrochemical reaction can be enhanced by Na+ doping the cathode material. [ABSTRACT FROM AUTHOR]

Searching for novel high-capacity electrode materials combining cationic and anionic redox processes is an ever-growing activity within the field of Li-ion batteries. In this respect, we report on the exploration of the Li3RuyNb1-yO4 (0 ≤ y ≤ 1) system with an O/M ratio of 4 to maximize the number of oxygen lone pairs, responsible for the anionic redox. We show that this system presents a very rich crystal chemistry with the existence of four structural types, which derive from the rocksalt structure but differ in their cationic arrangement, creating either zigzag, helical, jagged chains or clusters. From an electrochemical standpoint, these compounds are active on reduction via a classical cationic insertion process. The oxidation process is more complex, because of the instability of the delithiated phase. Our results promote the use of the rich Li3MO4 family as a viable platform for a better understanding of the relationships between structure and anionic redox activity. [ABSTRACT FROM AUTHOR]

Our whole-cell biocatalyst with a polydopamine nanocoating shows high catalytic activity (5 times better productivity than the native cell) and reusability (84% of the initial yield after 5 batches, 8 times higher than the native cell) in asymmetric reduction. It also integrates with titania, silica, and magnetic nanoparticles for multi-functionalization. [ABSTRACT FROM AUTHOR]

A series of BiVO 4 /3DOM TiO 2 nanocomposites have been synthesized and their photocatalytic activity was investigated under visible light irradiation using the RhB dye as model pollutant molecule in an aqueous solution. The effect of the amount of BiVO 4 as visible light sensitizer on the photocatalytic activity of BiVO 4 /3DOM TiO 2 nanocomposites was highlighted. The heterostructured composite system leads to much higher photocatalytic efficiencies than bare 3DOM TiO 2 and BiVO 4 nanoparticles. As the proportion of BiVO 4 in BiVO 4 /3DOM TiO 2 nanocomposites increases from 0.04 to 0.6, the photocatalytic performance of the BiVO 4 /3DOM TiO 2 nanocomposites increases and then decreases after reaching a maximum at 0.2. This improvement in photocatalytic perfomance is related to 1) the interfacial electron transfer efficiency between the coupled materials, 2) the 3DOM TiO 2 inverse opal structure with interconnected pores providing an easy mass transfer of the reactant molecules and high accessibility to the active sites and large surface area and 3) the effect of light sensitizer of BiVO 4 . Intensive studies on structural, textural, optical and surface properties reveal that the electronic interactions between BiVO 4 and TiO 2 lead to an improved charge separation of the coupled BiVO 4 /TiO 2 system. The photogenerated charge carrier densities increase with increasing the BiVO 4 content, which acts as visible light sensitizer to the TiO 2 and is responsible for the enhancement in the rate of photocatalytic degradation. However, the photocatalytic activity is reduced when the BiVO 4 amount is much higher than that of 3DOM TiO 2 . Two reasons could account for this behavior. First, with increasing BiVO 4 content, the photogenerated electron/hole pairs are accumulated at the surface of the BiVO 4 nanoparticles and the recombination rate increases as shown by the PL results. Second, decreasing the amount of 3DOM TiO 2 in the nanocomposite decreases the surface area as shown by the BET results. Moreover, the poor adsorptive properties of the BiVO 4 photocatalyst also affect the photocatalytic performance, in particular at higher BiVO 4 content. The present work demonstrates that BiVO 4 /3DOM TiO 2 is a very promising heterojunction system for visible light photocatalytic applications. [ABSTRACT FROM AUTHOR]

Thickness-driven electronic phase transitions are broadly observed in different types of functional perovskite heterostructures. However, uncertainty remains whether these effects are solely due to spatial confinement, broken symmetry, or rather to a change of structure with varying film thickness. Here, this study presents direct evidence for the relaxation of oxygen-2p and Mn-3d orbital (p-d) hybridization coupled to the layer-dependent octahedral tilts within a La2/3Sr1/3MnO3 film driven by interfacial octahedral coupling. An enhanced Curie temperature is achieved by reducing the octahedral tilting via interface structure engineering. Atomically resolved lattice, electronic, and magnetic structures together with X-ray absorption spectroscopy demonstrate the central role of thickness-dependent p-d hybridization in the widely observed dimensionality effects present in correlated oxide heterostructures. [ABSTRACT FROM AUTHOR]

The realization of metal nanoparticles (NPs) with bimetallic character and distinct composition for specific catalytic applications is an intensively studied field. Due to the synergy between metals, most bimetallic particles exhibit unique properties that are hardly provided by the individual monometallic counterparts. However, as small-sized NPs possess high surface energy, agglomeration during catalytic reactions is favored. Sufficient stabilization can be achieved by confinement of NPs in porous support materials. In this sense, metal-organic frameworks (MOFs) in particular have gained a lot of attention during the last years; however, encapsulation of bimetallic species remains challenging. Herein, the exclusive embedding of preformed core-shell PdPt and RuPt NPs into chemically robust Zr-based MOFs is presented. Microstructural characterization manifests partial retention of the core-shell systems after successful encapsulation without harming the crystallinity of the microporous support. The resulting chemically robust NP@UiO-66 materials exhibit enhanced catalytic activity towards the liquid-phase hydrogenation of nitrobenzene, competitive with commercially used Pt on activated carbon, but with superior size-selectivity for sterically varied substrates. [ABSTRACT FROM AUTHOR]

SmFe 8.75 Si 0.25 C/ α -Fe nanocomposites have been successfully synthesized using high energy milling, followed by annealing at 750 °C. The crystal structure of these compounds was characterized by the Rietveld method using powder X-ray diffraction data. By increasing the concentration of Sm, we observed a decrease in the amount of α -Fe phase. The morphology of the samples was determined by scanning and transmission electron microscopy. The average grain size is about 20 nm. The magnetic properties were investigated at room temperature and at 10 K. A ferromagnetic behavior was observed in all samples at both temperatures. An increase of the soft magnetic phase α -Fe induced an increase in the magnetization and a decrease in coercivity. [ABSTRACT FROM AUTHOR]

A new hierarchical MOF consisting of Cu(II) centers connected by benzene-tricarboxylates (BTC) is prepared by thermoinduced solid transformation of a dense CuBTC precursor phase. The mechanism of the material formation has been thoroughly elucidated and revealed a transformation of a ribbon-like 1D building unit into 2D layers and finally a 3D network. The new phase contains excess copper, charge compensated by systematic hydroxyl groups, which leads to an open microporous framework with tunable permanent mesoporosity. The new phase is particularly attractive for molecular separation. Energy consumption of adsorptive separation processes can be lowered by using adsorbents that discriminate molecules based on adsorption entropy rather than enthalpy differences. In separation of a 11-component mixture of C1-C6 alkanes, the hierarchical phase outperforms the structurally related microporous HKUST-1 as well as silicate-based hierarchical materials. Grand canonical Monte Carlo (GCMC) simulation provides microscopic insight into the structural host-guest interaction, confirming low adsorption enthalpies and significant entropic contributions to the molecular separation. The unique three-dimensional hierarchical structure as well as the systematic presence of Cu(II) unsaturated coordination sites cause this exceptional behavior. [ABSTRACT FROM AUTHOR]

Photo-activated processes have been widely recognized as cost-effective and environmentally friendly routes for both renewable energy generation and purification/cleaning technologies. We report herein on a plasma-assisted approach for the synthesis of Fe 2 O 3 -TiO 2 nanosystems functionalized with Au nanoparticles. Fe 2 O 3 nanostructures were grown by plasma enhanced-chemical vapor deposition, followed by the sequential sputtering of titanium and gold under controlled conditions, and final annealing in air. The target nanosystems were subjected to a thorough multi-technique characterization, in order to elucidate the interrelations between their chemico-physical properties and the processing conditions. Finally, the functional performances were preliminarily investigated in both sunlight-assisted H 2 O splitting and photocatalytic activity tests in view of self-cleaning applications. The obtained results highlight the possibility of tailoring the system behaviour and candidate the present Fe 2 O 3 -TiO 2 -Au nanosystems as possible multi-functional low-cost platforms for light-activated processes. [ABSTRACT FROM AUTHOR]

We report the controlled preparation of water processable nanoparticles (NPs) employing the push-pull polymer PCDTBT and the fullerene acceptor PC 71 BM in order to enable solar cell processing using eco-friendly solvent (i.e. water). The presented method provides the possibility to separate the formation of the active layer blend and the deposition of the active layer into two different processes. For the first time, the benefits of aqueous processability for the high-potential class of push-pull polymers, generally requiring high boiling solvents, are made accessible. With our method we demonstrate excellent control over the blend stoichiometry and efficient mixing. Furthermore, we provide visualization of the nanomorphology of the different NPs to obtain structural information down to ~2 nm resolution using advanced analytical electron microscopy. The imaging directly reveals very small compositional demixing in the PCDTBT:PC 71 BM blend NPs, in the size range of about <5 nm, indicating fine mixing at the molecular level. The suitability of the proposed methodology and materials towards the aspects of eco-friendly processing of organic solar cells is demonstrated through a processing of lab scale NPs solar cell prototypes reaching a power conversion efficiency of 1.9%. [ABSTRACT FROM AUTHOR]

Towards the development of novel drug carriers for oral delivery of poorly soluble drugs mesoporous aerogel carbons (CAs), namely CA10 and CA20 with different pore sizes (10 and 20 nm, respectively), were evaluated. The non-steroidal anti-inflammatory lipophilic compound ibuprofen was incorporated via passive loading. The drug loaded carbon aerogels were systemically investigated by means of High-Resolution Transmission Electron Microscopy (HR-TEM), Nitrogen physisorption studies, X-ray diffraction (XRD), Differential Scanning Calorimetry (DSC), X-ray photon electron spectroscopy (XPS) and ζ-potential studies. In vitro release studies were performed in simulated intestinal fluids reflecting both fasted (FaSSIF) and fed (FeSSIF) state conditions. Cytotoxicity studies were conducted with human intestinal cells (Caco-2). Drug was in an amorphous state in the pores of the carbon carrier as shown from the physicochemical characterization studies. The results showed marked differences in the release profiles for ibuprofen from the two aerogels in the media tested whereas in vitro toxicity profiles appear to be compatible with potential therapeutic applications at low concentrations. [ABSTRACT FROM AUTHOR]

The recent revival of the Na-ion battery concept has prompted intense activities in the search for new Na-based layered oxide positive electrodes. The largest capacity to date was obtained for a Na-deficient layered oxide that relies on cationic redox processes only. To go beyond this limit, we decided to chemically manipulate these Na-based layered compounds in a way to trigger the participation of the anionic network. We herein report the electrochemical properties of a Na-rich phase Na2IrO3, which can reversibly cycle 1.5 Na+ per formula unit while not suffering from oxygen release nor cationic migrations. Such large capacities, as deduced by complementary XPS, X-ray/neutron diffraction and transmission electron microscopy measurements, arise from cumulative cationic and anionic redox processes occurring simultaneously at potentials as low as 2.7 V vs Na+/Na. The inability to remove more than 1.5 Na+ is rooted in the formation of an O1-type phase having highly stabilized Na sites as confirmed by DFT calculations, which could rationalize as well the competing metal/oxygen redox processes in Na2IrO3. This work will help to define the most fertile directions in the search for novel high energy Na-rich materials based on more sustainable elements than Ir. [ABSTRACT FROM AUTHOR]

Heterogeneous metal catalysts enable the direct conjugation of linoleic acid tails in vegetable oil to their conjugated linoleic acid (CLA) isomers. CLA-enriched oils are useful as renewable feedstock for the chemical industry and as nutraceutical. Up to now, a solvent-free process for conjugated oils without significant formation of undesired hydrogenation products was not existing. This work shows the design of Ru/USY catalysts able to directly conjugate highly unsaturated vegetable oils such as safflower oil in absence of solvent and hydrogen. Key is fast molecular transport of the bulky reagent and reactive product triglycerides in the zeolite crystal. A two-step zeolite post-synthetic treatment (with NH 4 OH and acetate salt) was applied to create the necessary mesoporosity. More open zeolite structures allow for a faster conjugation reaction, while securing a fast removal of the reactive conjugated triglycerides, otherwise rapidly deactivating through fouling and pore blockage by polymers. The best Ru/USY catalyst in this contribution is capable of producing exceptionally high yields of conjugated oils, containing up to almost 30 wt% conjugated fatty acid tails in safflower oil, at an initial production rate of 328 g CLA mL −1 h −1 per gram metal catalyst. [ABSTRACT FROM AUTHOR]

The chromium-based metal-organic framework MIL-101(Cr) served as a host for the in situ synthesis of Fe3O4 nanoparticles. This hybrid nanomaterial was tested as an adsorbent for arsenite and arsenate species in groundwater and surface water and showed excellent affinity towards AsIII and AsV species. The adsorption capacities of 121.5 and 80.0 mg g-1 for arsenite and arsenate species, respectively, are unprecedented. The presence of Ca2+, Mg2+, and phosphate ions and natural organic matter does not affect the removal efficiency or the selectivity. The structural integrity of the hybrid nanomaterial was maintained during the adsorption process and even after desorption through phosphate elution. Additionally, no significant leaching of Cr or Fe species was observed. [ABSTRACT FROM AUTHOR]

Nanoscale Zr-based metal organic frameworks (MOFs) UiO-66 and UiO-67 were studied as potential anticancer drug delivery vehicles. Two model drugs were used, hydrophobic paclitaxel and hydrophilic cisplatin, and were adsorbed onto/into the nano MOFs (NMOFs). The drug loaded MOFs were further encapsulated inside a modified poly(ε-caprolactone) with d -α-tocopheryl polyethylene glycol succinate polymeric matrix, in the form of microparticles, in order to prepare sustained release formulations and to reduce the drug toxicity. The drugs physical state and release rate was studied at 37 °C using Simulated Body Fluid. It was found that the drug release depends on the interaction between the MOFs and the drugs while the controlled release rates can be attributed to the microencapsulated formulations. The in vitro antitumor activity was assessed using HSC-3 (human oral squamous carcinoma; head and neck) and U-87 MG (human glioblastoma grade IV; astrocytoma) cancer cells. Cytotoxicity studies for both cell lines showed that the polymer coated, drug loaded MOFs exhibited better anticancer activity compared to free paclitaxel and cisplatin solutions at different concentrations. [ABSTRACT FROM AUTHOR]