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Lithium lanthanum titanate (LLTO) perovskite is one of the most promising electrolytes for all-solid-state batteries, but its performance is limited by the presence of grain boundaries (GBs). The fraction of GBs can be significantly reduced by the preparation of coarse-grained LLTO ceramics. In this work, we describe an alternative approach to the fabrication of ceramics with large LLTO grains based on self-seeded grain growth. In compositions with the starting stoichiometry for the Li0.20La0.60TiO3phase and with a high excess addition of Li (Li:La:Ti = 11:15:25), microstructure development starts with the formation of the layered RP-type Li2La2Ti3O10phase. Grains with many RP-type defects initially develop into large platelets with thicknesses of up to 10 μm and lengths over 100 μm. Microstructure development continues with the crystallization of LLTO perovskite, epitaxially on the platelets and as smaller grains with thinner in-grain RP-lamellae. Theoretical calculations confirmed that the formation of RP-type sequences is energetically favored and precedes the formation of the LLTO perovskite phase. At around 1250 °C, the RP-type sequences become thermally unstable and gradually recrystallize to LLTO via the ionic exchange between the Li-rich RP-layers and the neighboring Ti and La layers as shown by quantitative HAADF-STEM. At higher sintering temperatures, LLTO grains become free of RP-type defects and the small grains recrystallize onto the large platelike seed grains via Ostwald ripening. The final microstructure is coarse-grained LLTO with total ionic conductivity in the range of 1 × 10–4S/cm.

A γ-alumina support functionalized with transition metals is one of the most widely used industrial catalysts for the total oxidation of volatile organic compounds (VOCs) as air pollutants at higher temperatures (280–450 °C). By rational design of a bimetal CuFe-γ-alumina catalyst, synthesized from a dawsonite alumina precursor, the activity in total oxidation of toluene as a model VOC at a lower temperature (200–380 °C) is achieved. A fundamental understanding of the catalyst and the reaction mechanism is elucidated by advanced microscopic and spectroscopic characterizations as well as by temperature-programmed surface techniques. The nature of the metal–support bonding and the optimal abundance between Cu–O–Al and Fe–O–Al species in the catalysts leads to synergistic catalytic activity promoted by small amounts of iron (Fe/Al = 0.005). The change in the metal oxide–cluster alumina interface is related to the nature of the surfaces to which the Cu atoms attach. In the most active catalyst, the CuO6octahedra are attached to 4 Al atoms, while in the less active catalyst, they are attached to only 3 Al atoms. The oxidation of toluene occurs via the Langmuir–Hinshelwood mechanism. The presented material introduces a prospective family of low-cost and scalable oxidation catalysts with superior efficiency at lower temperatures.

A versatile approach to the production of cluster- and single atom-based thin-film electrode composites is presented. The developed TiOxNy–Ir catalyst was prepared from sputtered Ti–Ir alloy constituted of 0.8 ± 0.2 at % Ir in α-Ti solid solution. The Ti–Ir solid solution on the Ti metal foil substrate was anodically oxidized to form amorphous TiO2–Ir and later subjected to heat treatment in air and in ammonia to prepare the final catalyst. Detailed morphological, structural, compositional, and electrochemical characterization revealed a nanoporous film with Ir single atoms and clusters that are present throughout the entire film thickness and concentrated at the Ti/TiOxNy–Ir interface as a result of the anodic oxidation mechanism. The developed TiOxNy–Ir catalyst exhibits very high oxygen evolution reaction activity in 0.1 M HClO4, reaching 1460 A g–1Irat 1.6 V vs reference hydrogen electrode. The new preparation concept of single atom- and cluster-based thin-film catalysts has wide potential applications in electrocatalysis and beyond. In the present paper, a detailed description of the new and unique method and a high-performance thin film catalyst are provided along with directions for the future development of high-performance cluster and single-atom catalysts prepared from solid solutions.

The atomic-level response of zigzag ferroelectric domain walls (DWs) was investigated with in situ bias scanning transmission electron microscopy (STEM) in a subcoercive-field regime. Atomic-level movement of a single DW was observed. Unexpectedly, the change in the position of the DW, determined from the atomic displacement, did not follow the position of the strain field when the electric field was applied. This can be explained as low mobility defect segregation at the initial DW position, such as ordered clusters of oxygen vacancies. Further, the triangular apex of the zigzag wall is pinned, but it changes its shape and becomes asymmetric under electrical stimuli. This phenomenon is accompanied by strain and bound charge redistribution. We report on unique atomic-scale phenomena at the DW level and show that in situ STEM studies with atomic resolution are very relevant as they complement, and sometimes challenge, the knowledge gained from lower resolution studies.

Deep cryogenic treatment (DCT) has arisen as a promising green technology to modify the properties of metallic materials. Here we present a substantial (55%) improvement to the wear resistance of an Al-Mg-Si alloy using DCT without any deterioration of other mechanical properties. This improvement is attributed to a slight hardness increase resulting from multiscale microstructural modifications. DCT modifies the morphology of dispersoids as well as the organization and morphology of β’’ precipitates that increase their fraction (25%) at the expense of β’ precipitates. These effects are related to the greater nanoscale mobility and segregation of the alloying elements (Mg, Si) following DCT, resulting from lattice defect recombination. This research provides a fundamental breakthrough in understanding the DCT effect on aluminum alloys, confirming DCT as a feasible CO2-free treatment step towards improvement of aluminum alloys.

The hydrothermal synthesis of zinc oxide (ZnO) particles from zinc acetylacetonate monohydrate in “pure” aqueous solution and in aqueous NaOH solution at 90 °C is reported. The structural and morphological properties of ZnO particles were investigated by powder X-ray diffraction, X-ray absorption spectroscopy (XAS), field emission scanning electron microscopy, and transmission electron microscopy. The effect of NaOH on the growth mechanism and photocatalytic performance of hierarchical ZnO structures was investigated. The experimental findings, supported by results of quantum chemical calculations at the level of density functional theory, were used to propose the mechanism of nucleation and preferential growth of finely tuned hollow and nonhollow ZnO structures and their effects on the photocatalytic activity. The calculations indicate that the process of ZnO nucleation in “pure” aqueous solution mainly proceeds by the reaction of small monomers, while tetramers play a crucial role in aqueous NaOH solution. Both the preferred ZnO nanostructure and microstructure growth processes are driven by O–H···O hydrogen bonds as controlling elements. The calculated values of the EO···Hinteraction indicate a stronger interaction via O–H···O hydrogen bonds in “pure” aqueous media (EO···H= −11.73 kcal mol–1) compared to those obtained in aqueous NaOH solution (EO···H= −8.41 kcal mol–1). The specific structural motif of the (ZnO–H2O)12dodecamers with calculated negative ΔG*INTfree release energy indicates that the formation of anisotropic nanocrystalline ZnO with the c-axis as the primary growth direction is spontaneous and accelerated exclusively in “pure” aqueous solution, whereas it is an unfavorable endergonic process in aqueous NaOH solution (ΔG*INT> 0). Efforts have been made to determine the photocatalytic efficiency of the ZnO samples based on the XAS measurements. ZnO particles obtained in “pure” aqueous solution show the highest photocatalytic activity due to the presence of a larger amount of oxygen vacancies.

Abstract: In this work, pure and copper-doped ceria (CuxCe1-xO2, x= 0, 0.1, 0.2, 0.3 and 0.4) nanoparticles were prepared using the organic additive- and template-free hydrothermal method, thermally treated and thoroughly characterized. The catalytic activity in the oxidation of volatile organic compounds was tested using benzene, toluene, ethylbenzene, and o-xylene gaseous mixture (BTEX). The obtained nanocatalysts consist of very small spherical particles with sizes between 12 and 8.4 nm. Even though the XPS results show that copper is incorporated into the ceria crystal lattice in amounts lower than nominal, a beneficial synergistic effect between copper and cerium species is visible in the overall properties of the prepared materials. The sample with 40 mol.% copper is particularly noteworthy representing a precedent in terms of the largest nominal doping amount without the occurrence of secondary phases achieved by hydrothermal synthesis, and exhibiting the best catalytic activity for all studied VOCs. Graphical abstract:

In the quest for designing efficient and stable photocatalytic materials for CO2reduction, hybridizing a selective noble-metal-free molecular catalyst and carbon-based light-absorbing materials has recently emerged as a fruitful approach. In this work, we report about Co quaterpyridine complexes covalently linked to graphene surfaces functionalized by carboxylic acid groups. The nanostructured materials were characterized by X-ray photoemission spectroscopy, X-ray absorption spectroscopy, IR and Raman spectroscopies, high-resolution transmission electron microscopy and proved to be highly active in the visible-light-driven CO2catalytic conversion in acetonitrile solutions. Exceptional stabilities (over 200 h of irradiation) were obtained without compromising the selective conversion of CO2to products (>97%). Most importantly, complete selectivity control could be obtained upon adjusting the experimental conditions: production of CO as the only product was achieved when using a weak acid (phenol or trifluoroethanol) as a co-substrate, while formate was exclusively obtained in solutions of mixed acetonitrile and triethanolamine.

Oxygen vacancies are known to play a crucial role in tuning the physical properties and technological applications of titanium dioxide TiO2. Over the last decades, defects in substoichiometric TiO2have been commonly associated with the formation of TinO2n–xMagnéli phases, which are extended planar defects originating from crystallographic shear planes. By combining advanced transmission electron microscopy techniques, electron energy-loss spectroscopy and atomistic simulations, we reach new understanding of the oxygen vacancy induced structural modulations in anatase, ruling out the earlier shear-plane model. Structural modulations are instead shown to be due to the formation of oxygen vacancy superstructures that extend periodically inside the films, preserving the crystalline order of anatase. Elucidating the structure of oxygen defects in anatase is a crucial step for improving the functionalities of such material system and to engineer devices with targeted properties.

Determination of the oxidation state and coordination geometry of iron in Fe-bearing minerals expands our knowledge obtained by standard mineralogical characterization. It provides information that is crucial in assessing the potential of minerals to interact with their surrounding environment and to generate reactive oxygen species, which can disrupt the normal function of living organisms. Aberration-corrected scanning transmission electron microscopy dual-electron energy-loss spectroscopy (acSTEM Dual-EELS) has only rarely been applied in environmental and medical mineralogy, but it can yield data that are essential for the description of near-surface and surface mechanisms involved in many environmental and health-related processes. In this study, we have applied the energy loss near-edge structure (ELNES) and L2,3white-line intensity-ratio methods using both the universal curve and progressively larger integrating windows to verify their effectiveness in satisfactorily describing the valence state of iron at amosite grain boundaries, and, at the same time, to estimate thickness in the same region of interest. The average valence state obtained from acSTEM Dual-EELS and from a simplified geometrical model were in good agreement, and within the range defined by the bulk and the measured surface-valence states. In the specific case presented here, the use of the universal curve was most suitable in defining the valence state of iron at amosite grain boundaries. The study of ELNES revealed an excellent correspondence with the valence state determined by the L2,3white-line intensity-ratio method through the use of the universal curve, and it seems that the spectra carry some information regarding the coordination geometry of Fe. The combination of visual examination, reconstruction of the grain boundaries through a simple geometrical model, and Dual-EELS investigation is a powerful tool for characterizing the grain boundaries of hazardous minerals and foreseeing their potential activity in an organism, with the possibility to describe toxic mechanisms in a stepwise fashion.

Compositionally complex materials (CCMs) have recently attracted great interest in electrocatalytic applications. To date, very few materials were systematically developed and tested due to the highly difficult preparation of high-surface-area CCMs. In this work, a surface of a compositionally complex FeCoNiCuZn alloy (CCA) was nitridated with subsequent anodization leading to morphological and compositional modifications. Notably, the electrochemical surface area and surface roughness as well as the electrocatalytic activity of the anodized material exhibit significant enhancement. Oxygen evolution reaction (OER) activity by the anodized CCN (CCN–AO) proceeds with remarkably small overpotential (233 mV) at 10 mA cm−2in 1 M KOH. Experimental characterization indicates that the oxidation state of Co plays a critical role in the Fe–Co–Ni electrocatalyst. The developed approach and design strategy open up immense prospects in the preparation of a new, affordable, scalable and effective type of complex and high-performance electrocatalytic electrodes with tunable properties.

Engineered solid–liquid interfaces will play an important role in the development of future energy storage and conversion (ESC) devices. In the present study, defective graphene oxide (GO) and reduced graphene oxide (rGO) structures were used as engineered interfaces to tune the selectivity and activity of Pt disk electrodes. GO was deposited on Pt electrodes via the Langmuir–Blodgett technique, which provided compact and uniform GO films, and these films were subsequently converted to rGO by thermal reduction. Electrochemical measurements revealed that both GO and rGO interfaces on Pt electrodes exhibit selectivity toward the oxygen reduction reaction (ORR), but they do not have an impact on the activity of the hydrogen oxidation reaction in acidic environments. Scanning transmission electron microscopy at atomic resolution, along with Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM), revealed possible diffusion sites for H2and O2gas molecules and functional groups relevant to the selectivity and activity of these surfaces. Based on these insights, rGO interfaces are further demonstrated to exhibit enhanced activity for the ORR in nonaqueous environments and demonstrate the power of our ex situengineering approach for the development of next-generation ESC devices.

The future significance of energy conversion has stimulated intense investigation of various electrocatalytic materials. Hence electrocatalysts have become the subject of electrochemical characterization on a daily basis. In certain cases of interest, when measuring electrochemical reactions beyond the onset potentials, however, appropriateness of existing electroanalytical methods may be questioned and alternative approaches need to be developed. The present study highlights some shortcomings in the electrochemical investigation of gas evolving reactions. The oxygen evolution reaction (OER) is selected as a case example with a specific focus on the electrochemical stability of a nanoparticulate iridium catalyst. When conventional electrochemical methods, such as thin film rotating disc electrodes are employed to study the materials’ stability, the intrinsic degradation is masked by oxygen bubbles, which are inherently being formed during the reaction, especially when high current densities are used. In this Letter, we present a solution to this issue, the so-called floating electrode arrangement. Its elegant usage enables fast and reliable electrochemical characterization of oxygen evolution electrocatalysts.

Catalytic properties of advanced functional materials are determined by their surface and near-surface atomic structure, composition, morphology, defects, compressive and tensile stresses, etc; also known as a structure–activity relationship. The catalysts structural properties are dynamically changing as they perform via complex phenomenon dependent on the reaction conditions. In turn, not just the structural features but even more importantly, catalytic characteristics of nanoparticles get altered. Definitive conclusions about these phenomena are not possible with imaging of random nanoparticles with unknown atomic structure history. Using a contemporary PtCu-alloy electrocatalyst as a model system, a unique approach allowing unprecedented insight into the morphological dynamics on the atomic-scale caused by the process of dealloying is presented. Observing the detailed structure and morphology of the same nanoparticle at different stages of electrochemical treatment reveals new insights into atomic-scale processes such as size, faceting, strain and porosity development. Furthermore, based on precise atomically resolved microscopy data, Kinetic Monte Carlo (KMC) simulations provide further feedback into the physical parameters governing electrochemically induced structural dynamics. This work introduces a unique approach toward observation and understanding of nanoparticles dynamic changes on the atomic level and paves the way for an understanding of the structure–stability relationship.

We investigated ceria nanoparticle/strongly charged polyelectrolyte solution interface on the example of adsorption of a strong polyelectrolyte poly(sodium 4-styrenesulfonate), PSS, on cerium oxide nanoparticles to quantitatively characterize the above-mentioned interface. The obtained results could enable a better prediction of nanoparticles behavior in polyelectrolyte solution which could lead to improved applications of ceria nanoparticles. We initially both synthetized and characterized ceria nanoparticles. For the characterization X-ray powder diffraction (XRD), bright-field scanning transmission electron microscopy (TEM), dynamic light scattering (DLS), and electrophoretic mobility measurements were used. Results revealed that nanoparticles are spherical with primary ceria nanoparticles diameter (nanocrystallite size) of approximately 3.5 nm. Results of high-resolution TEM, DLS, and electrophoretic mobility measurements after adsorption of PSS showed that polyelectrolyte-coated nanoparticles were obtained. The comparison of average hydrodynamic diameters of uncoated and PSS-coated ceria nanoparticles leads to the assumed thickness of the polyelectrolyte layer of δ ≈ 9 nm. Finally, for the quantitative interpretation of polyelectrolyte adsorption on ceria nanoparticles, the application of the modified Ohshima model was examined. In that respect, the adsorption parameters such as charge density of the polyelectrolyte layer electrophoretic softness and adsorption density were determined. It was thus shown that Ohshima model could be applied for studying ceria nanoparticle/strongly charged polyelectrolyte solution interface and that the obtained results could serve as a basis for further tailored applications of polyelectrolytes as stabilizing agents for nanoparticles.

Removal of contaminants of emerging concern (CEC) from water is a serious problem. Using sunlight to assist in this process is one of the most sustainable methods for water treatment. In this study, we demonstrate that tailoring the morphology and optimizing the metal concentration in the multicomponent catalysts through an appropriate synthetic strategy leads to Fenton-like and photo-Fenton-like systems capable of effectively degrading bisphenol A and coumarin as model endocrine disruptors and coumarin as a probe for •OH detection. Multicomponent Cu-Mn-Fe silica supported catalysts were prepared via direct synthesis by incorporating magnetic Fe3O4nanoparticles, Mn and Cu during the formation of silica nanoparticles with interparticle mesoporosity. Comprehensive characterization by advanced microscopic and spectroscopic techniques revealed qualitatively and quantitatively the presence of magnetic Fe oxides covered with the silica support, isolated Mn cations/oxo species into silica framework and CuO particles attached to the silica framework. The Fenton-like activities of the catalysts are due to the catalytic disproportionation of H2O2by Cu2+species and isolated Mn species in the silica support. The investigated catalysts are efficient concerning the homolytic cleavage of H2O2to hydroxyl radicals, with a further positive effect of hydroxyl radical formation observed under visible-light illumination thus acting as photo-Fenton-like catalysts. Fe oxides with magnetic properties are used for easy separation of the catalyst/photocatalyst after the reaction and do not contribute to the catalytic/photocatalytic performance.

Charging of material surfaces in aqueous electrolyte solutions is one of the most important processes in the interactions between biomaterials and surrounding tissue. Other than a biomaterial, titania nanotubes (TiO2NTs) represent a versatile material for numerous applications such as heavy metal adsorption or photocatalysis. In this article, the surface charge properties of titania NTs in NaNO3solution were investigated through electrophoretic mobility and polyelectrolyte colloid titration measuring techniques. In addition, we used high-resolution transmission electron microscopy imaging to determine the morphology of TiO2NTs. A theoretical model based on the classical density functional theory coupled with the charge regulation method in terms of mass action law was developed to understand the experimental data and to provide insights into charge properties at different physical conditions, namely, pH and NaNO3concentration. Two intrinsic protonation constants and surface site density have been obtained. The electrostatic properties of the system in terms of electrostatic potentials and ion distributions were calculated and discussed for various pH values. The model can quantitatively describe the titration curve as a function of pH for higher bulk salt concentrations and the difference in the equilibrium amount of charges between the inner and outer surfaces of TiO2NTs. Calculated counterion (NO3–) distributions show a pronounced decrease of NO3–ions for high bulk pH (both inside and outside TiO2NT) because of the strong electric field. With the decrease of bulk pH or the increase of the salt concentration, NO3–is able to accumulate near the TiO2NTs surfaces.

Gold nanoparticles (AuNPs) were synthesized in a microemulsion water/Triton X-100/1-pentanol/cyclohexane using various reducing agents. Basically, three microemulsion syntheses of AuNPs were studied: (i) one using a strong chemical reducing agent (NaBH4), (ii) another using γ-irradiation under moderately strong reducing/oxidizing conditions, and (iii) yet another under highly oxidizing conditions (with the addition of NaOH aqueous solution). All the three were performed at room temperature. When a strong chemical reducing agent NaBH4was used in the microemulsion, gold crystallites 11.7 nm in size were obtained, as determined on the basis of X-ray powder diffraction line broadening. The γ-irradiation of nitrogen-saturated microemulsion at the acidic pH produced AuNPs about 12 nm in size, which under the isolation by centrifugation aggregated into large preconcentrated AuNPs about 150 nm in size. These AuNPs possess thixotropic properties. The microemulsion stirred at room temperature and at the pH < 7 under oxidizing conditions did not produce gold nanoparticles. Under the identical experimental conditions and at the pH > 7 (stronger oxidizing conditions), well-dispersed AuNPs 12 nm in size were formed. The microemulsion synthesis of AuNPs in the alkaline range but not at an acidic pH was explained by the oxidation of alcohol groups (–OH) into carbonyl groups (>C=O) due to the catalytic action of hydroxyl ions and gold. In parallel with the catalytic oxidation of alcohol groups in microemulsion, the Au(III) were reduced with the subsequent formation of gold nanoparticles. The synthesis of AuNPs in 1-pentanol by adding the aqueous NaOH solution at room temperature without using microemulsions confirmed the role of the base-catalyzed oxidation of alcohols in the formation of AuNPs. Based on the findings in this study, we propose the base-catalyzed alcohol oxidation at room temperature as a new, simple, and versatile synthesis route for obtaining gold nanoparticles. The results of this study suggest that the classical approach of using a reducing agent for the synthesis of AuNPs is not a determining factor, since a diametrically opposite approach to the synthesis of AuNPs can be used, namely, stimulating the oxidation of the functional organic groups in close proximity to gold ions.

Synthesis, structure, morphology, and detailed spectroscopic and crystal-field analysis of Mn4+doped Mg2TiO4nanoparticles (NPs) are presented. These Mg2TiO4:Mn4+NPs are obtained through a Pechini-type polymerized complex route and calcination at 600 °C, and are approximately 10 nm in diameter and loosely agglomerated into 1-μm particles, as evidenced from transmission electron microscopy. These NPs exhibit strong, sharp red emission at 658 nm (with a 1.2 ms emission decay) as a result of the spin-forbidden 2Eg→ 4A2gelectron transition of the tetravalent manganese ions. No signatures of the presence of manganese ions in divalent or trivalent valence states are observed in the NPs with either photoluminescence or diffuse reflection spectroscopy. The energy levels of the Mn4+ions in a trigonal crystal field of Mg2TiO4are calculated using the exchange-charge model and are well matched with the experimental photoluminescence excitation and emission spectra. The absolute values of the calculated crystal-field parameters (CFPs) are similar to those reported for trigonal point symmetry at Mn4+dopant sites (Y2Ti2O7, Y2Sn2O7, and Na2SiF6). It is also observed that the contributions of covalent and exchange effects to the CFPs are nearly eight times greater than the point-charge contribution.

A photocatalytic, TiO2-based microreactor is designed and fabricated on a metal–titanium foil. The microchannel is mechanically engraved in the substrate foil, and a double-layered TiO2anatase film is immobilized on its inner walls with a two-step synthesis, which included anodization and a hydrothermal treatment. X-ray diffraction (XRD) and scanning electron microscopy (SEM) confirm the presence of an approximately 10-μm-thick layer of titania nanotubes and anatase nanoparticles. The SEM and transmission electron microscopy (TEM) of the cross sections show a dense interface between the titanium substrate and the TiO2nanotubes. An additional layer of TiO2-anatase nanoparticles on the top of the film provides a large, photocatalytic surface area. The metal–titanium substrate with a functionalized serpentine channel is sealed with UV-transparent Plexiglas, and four 0.8-mW UV LEDs combined with a power controller on a small printed-circuit board are fixed over the substrate. The photocatalytic activity and the kinetic properties for the degradation of caffeine are provided, and the longer-term stability of the TiO2film is evaluated. The results show that after 6 months of use and 3600 working cycles the microreactor still exhibits 60% of its initial efficiency.

With the advancement of drug delivery systems based on mesoporous silica nanoparticles (MSNs), a simple and efficient method regulating the drug release kinetics is needed. We developed redox-responsive release systems with three levels of hindrance around the disulfide bond. A model drug (rhodamine B dye) was loaded into MSNs’ mesoporous voids. The pore opening was capped with β-cyclodextrin in order to prevent leakage of drug. Indeed, in absence of a reducing agent the systems exhibited little leakage, while the addition of dithiothreitol cleaved the disulfide bonds and enabled the release of cargo. The release rate and the amount of released dye were tuned by the level of hindrance around disulfide bonds, with the increased hindrance causing a decrease in the release rate as well as in the amount of released drug. Thus, we demonstrated the ability of the present mesoporous systems to intrinsically control the release rate and the amount of the released cargo by only minor structural variations. Furthermore, an in vivoexperiment on zebrafish confirmed that the present model delivery system is nonteratogenic.

Layered ZnO microspheric particles were prepared by the thermal decomposition of layered hydrozincite (LZnHC), which was synthesized from zinc nitrate and urea in a water/PEG400 mixture. The influence of the starting reagents, their concentrations, and the amount of PEG in the water/PEG400 mixture on the particle growth was observed. The chemical aspect of the particle growth was proposed in the frame of the partial charge model (PCM), and the formation of [Zn(OH)2(OH2)4]0and [Zn(OH)(HCO3)(OH2)3]0was predicted for the solid phase. The assumed growth mechanism, which follows the “nonclassical crystallization” concept of a self‐assembling mechanism, was observed in situ by small‐angle X‐ray scattering (SAXS) and predicts the rapid formation of approximately 6 nm sized building units. The size of these nano building units, stable only in the reaction medium, remains nearly constant during the synthesis, as the concentration of the nano building units increases throughout the reaction. The nano building units connect into leaves of LZnHC with a thickness of 20 nm. These leaves of LZnHC are further agglomerated into porous, microsphere‐like particles with sizes up to 4 μm.

For a nonzero rational number q, a rationalD(q)-n-tupleis a set of ndistinct nonzero rationals {a1,a2,⋯,an}such that aiaj+qis a square for all 1⩽i

Current trends in data processing have given impetus for an intense search of new concepts of memory devices with emphasis on efficiency, speed, and scalability. A promising new approach to memory storage is based on resistance switching between charge-ordered domain states in the layered dichalcogenide 1T-TaS2. Here we investigate the energy efficiency scaling of such charge configuration memory (CCM) devices as a function of device size and data write time τWas well as other parameters that have bearing on efficient device operation. We find that switching energy efficiency scales approximately linearly with both quantities over multiple decades, departing from linearity only when τWapproaches the ∼0.5 ps intrinsic switching limit. Compared to current state of the art memory devices, CCM devices are found to be much faster and significantly more energy efficient, demonstrated here with two-terminal switching using 2.2 fJ, 16 ps electrical pulses.

Thermal annealing processes for supported Pt-based nanoparticles are usually developed based on iterative empirical findings resulting from ex-situcharacterization of pre- and post-annealed samples. Such an approach, however, offers limited insight into processes occurring during the heating step. In this work, we first exemplify typical findings that are accessible by ex-situinvestigation using typical conventional techniques such as transmission electron microscopy (TEM), X-ray diffraction (XRD), and thin film – rotating disc electrode (TF-RDE). As a model system we select a well-researched Pt-Cu alloy which, as demonstrated, offers exciting new insights into the dynamics occurring during heat treatment on the nano-to-atomic scale. This dynamics can be viewed by upgrading the ex-situfindings with a high resolution TEM imaging in combination with carefully designed in-situheating protocol. This way one can directly observe the particle growth mechanisms during heat treatment. Such direct observations, in turn, provide new understanding of morphology-performance correlations in alloys. For example, it is shown that the enhanced activity of the present PtCu3/C electrocatalyst is due to Cu enrichment during heat treatment. This enrichment, however, is only possible due to the presence of relatively large excess CuO needle-like particles left over from the previous double passivation galvanic displacement step. Very importantly, we further show that the mechanism of Cu enrichment at elevated temperatures involves migration of Cu single atoms viathe carbon support. At moderate temperatures (up to 500 °C), other effects have also been observed such as reshaping into a sphere-like shape as well as ordering of the crystal lattice which could not occur without enrichment of the initial Pt-Cu nanoparticles with Cu. In that region, Cu enrichment is also responsible for the initial growth of PtCu nanoparticles. By contrast, upon heating till 800 °C, the growth is mainly due to coalescence. Ostwald ripening, on the other hand, does not seem to play a significant role in the increase in the nanoparticle size. The new general insights can be readily extended to various other similar alloy systems.