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In situ NAP-XPS and XAS are used to elucidate the mechanisms of the exsolution/reoxidation process in Sr0.93Ti0.3Fe0.63Ni0.07O3−δ (STFN) perovskite, used as an electrode for intermediate temperature-SOFC.

Applications of advanced cathode materials with well designed chemical components and or optimized nanostructures promoting the sulfur redox kinetics and suppressing the shuttle effect of polysulfides are highly valued. However, in the case of actual lithium sulfur Li amp; 8722;S batteries under practical working conditions, one long term obstacle still exists, which is mainly due to the difficulties in massive synthesis of such nanomaterials with low cost and ease of control on the nanostructure. Herein, we develop a facile synthesis of carbon coated Ti4O7 hollow nanoparticles C amp; 8722;Ti4O7 using spherical polymer electrolyte brush as soft template, which is scalable via utilizing a minipilot reactor. The C amp; 8722;Ti4O7 hollow nanoparticles provide strong chemical adsorption to polysulfides through the large polar surface and additional physical confinement by rich micro amp; mesopores and have successfully been employed as an efficient sulfur host for multilayer pouch cells. Besides, the sluggish kinetics of the sulfur and lithium sulfide redox mechanism can be improved by the highly conductive Ti4O7 via catalyzation of the conversion of polysulfides. Consequently, the C amp; 8722;Ti4O7 based pouch cell endows a high discharge capacity of 1003 amp; 8197;mAh amp; 8201;g amp; 8722;1 at 0.05 amp; 8197;C, a high capacity retention of 83.7 amp; 8201; after 100 amp; 8197;cycles at 0.1 amp; 8197;C, and a high Coulombic efficiency of 97.5 amp; 8201; at the 100th cycle. This work proposes an effective approach to transfer the synthesis of hollow Ti4O7 nanoparticles from lab to large scale production, paving the way to explore a wide range of advanced nanomaterials for multilayer Li amp; 8722;S pouch cells

High-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) employing a phosphoric acid H3PO4-doped membrane are considered to be promising sustainable electrochemical energy storage. The high-temperature operation has several advantages, such as a higher tolerance to CO poisoning, allowing coupling of HT-PEMFCs with reformers [1-3], as well the possibility for heat and electric energy co-generation [1,2]. However, during operation, phosphorus oxo-acids (e.g.: H3PO3) are generated on the anode. These impurities adsorb on the Pt catalyst [4-6], thus possibly negatively affecting the HT-PEMFCs performance. A detailed understanding of the H3PO3-catalyst (Pt) interaction is hence necessary for further HT-PEMFC optimization. However, besides an investigation of the H3PO3 adsorption behavior on Pt [6,7], literature on the behavior of the H3PO3 in contact with Pt (with/without polarization) is scarce. In this work, the oxidation mechanism of H3PO3 was investigated using a combination of in situ x-ray spectroscopy techniques that directly probe the H3PO3/Pt interface interaction, complemented by ex situ x-ray photoelectron spectroscopy (XPS) and ion-exchange chromatography (IEC). IEC gave insights into the effect of Pt on the stability of deaerated aqueous H3PO3 solutions. XPS was conducted on H3PO3/support structures (including Au and Pt supports) to determine to what extent the support affects the H3PO3 oxidation. Furthermore, in-situ dip and pull near-ambient pressure (NAP-)XPS was conducted to investigate the state of H3PO3 at the H3PO3/Pt interface and in solution bulk. It was observed that at the H3PO3/Pt interface, H3PO3 was chemically oxidized to H3PO4, while in the bulk solution it remains stable, as shown in Figure 1. Moreover, in situ x-ray absorption spectroscopy at the P K-edge was conducted at different concentrations of H3PO3 in aqueous solutions (i.e., different amounts of H2O) in contact with Pt, to determine the role of H2O in the oxidation of H3PO3. A higher degree of oxidation was observed for the less concentrated H3PO3, implying that H2O participates in the oxidation mechanism of H3PO3 to H3PO4. References: [1] Chandan et al., A.. J. Power Sources 2013, 231, 264–278. [2] Asensio, et al. Chem. Soc. Rev. 2010, 39 (8), 3210. [3] Q. Li et al, J. Electrochem. Soc. 2003, 150 (12), A1599. [4] Sugishima et al, J. Electrochem. Soc. 1994, 141 (12), 3332. [5] Doh et al. ChemElectroChem. 2014, 1 (1), 180–186. [6] Prokop et al, Electrochimica Acta 2015, 160, 214–218. [7] Prokop et al, Electrochimica Acta 2016, 212, 465–472. Figure 1

Anatase TiO2 represents an attractive electrode material for application in sodium-ion batteries due to its relatively low cost, high environmental compatibility, high intrinsic safety, conferred b...

The underlying beneficial mechanism of heavy alkali postdeposition treatment (PDT) of Cu(In,Ga)Se

The successful translation of nanoparticle-based systems into commercial products depends upon the ability to reliably measure important physical and chemical properties of these particles. The density of nanoparticles is one such property, because it provides important information about the composition of the material. In this work, an analytical centrifugation approach based on line-start centrifugal sedimentation and flotation measurements is described. The two independent measurements permit both the size and the density of these nanoparticles to be determined with excellent precision. A set of monodisperse polystyrene nanoparticles of different sizes is used to demonstrate this method. The density and size measurements are validated by comparison to accurate Small Angle X-ray Scattering (SAXS) analysis for particles within the size range of SAXS, i.e. less than ∼300 nm in diameter. Both sedimentation and flotation measurements produce consistent high resolution size distributions of the particles and the measured size and density values are identical, within experimental uncertainty, to the SAXS results. This approach has the potential to provide useful characterisation of a range of particles of interest, for example, for medical application, such as liposomes and polymeric drug carriers.

The industrial exploitation of high value nanoparticles is in need of robust measurement methods to increase the control over product manufacturing and to implement quality assurance. InNanoPart, a European metrology project responded to these needs by developing methods for the measurement of particle size, concentration, agglomeration, surface chemistry and shell thickness. This paper illustrates the advancements this project produced for the traceable measurement of nanoparticle number concentration in liquids through small angle X-ray scattering (SAXS) and single particle inductively coupled plasma mass spectrometry (spICPMS). It also details the validation of a range of laboratory methods, including particle tracking analysis (PTA), dynamic light scattering (DLS), differential centrifugal sedimentation (DCS), ultraviolet visible spectroscopy (UV-vis) and electrospray-differential mobility analysis with a condensation particle counter (ES-DMA-CPC). We used a set of spherical gold nanoparticles with nominal diameters between 10 nm and 100 nm and discuss the results from the various techniques along with the associated uncertainty budgets.

The industrial exploitation of high value nanoparticles is in need of robust measurement methods to increase the control over product manufacturing and to implement quality assurance. InNanoPart, a European metrology project responded to these needs by developing methods for the measurement of particle size, concentration, agglomeration, surface chemistry and shell thickness. This paper illustrates the advancements this project produced for the traceable measurement of nanoparticle number concentration in liquids through small angle X-ray scattering (SAXS) and single particle inductively coupled plasma mass spectrometry (spICPMS). It also details the validation of a range of laboratory methods, including particle tracking analysis (PTA), dynamic light scattering (DLS), differential centrifugal sedimentation (DCS), ultraviolet visible spectroscopy (UV-vis) and electrospray-differential mobility analysis with a condensation particle counter (ES-DMA-CPC). We used a set of spherical gold nanoparticles with nominal diameters between 10 nm and 100 nm and discuss the results from the various techniques along with the associated uncertainty budgets.

Polymeric colloids are of growing importance in nanomedicine for drug or imaging agent delivery. Their characterization is a crucial task but their traceable size determination is challenging, especially for particles with a complicated inner structure. This work describes the simultaneous determination of the size distribution and the density of polymeric particles by means of continuous contrast variation in small angle X-ray scattering (SAXS), which also reveals the inner structure of the colloids. The applicability of the technique has been evaluated by the comparison with other techniques, with focus on differential centrifugal sedimentation (DCS) in terms of the measured density. A novel approach to DCS is presented, which employs two centrifuge setups to enable the density and size determination of particles with physical densities close to water.

Sodium-ion-batteries (SIBs) are considered one of the most promising next-generation battery systems. [1] Owing to their potential lower cost and higher sustainability compared to the current lithium-based technology, SIBs have the potential to dominate the future stationary storage market filling the gap between energy production and utilization. [2] Currently, hard carbon represents the anode of choice for SIBs. Bio-waste derived hard carbons, in particular, are certainly the most attractive among others in terms of sustainability and cost. [3,4]. Recently, there has been a great interest in the fundamental understanding of the sodiation process. Indeed, several mechanisms have been proposed, however, the unresolved nature of the hard carbon structure hinders a comprehensive description of the sodiation mechanism. [3] Nonetheless, the understanding of the Na uptake and release is crucial for a rational design of improved hard carbon anodes. The most commonly detected sodiation processes have been identified as:ⅰ) inter-lamellae Na-ion intercalation, ⅱ) Na-ion ad-/chemisorption at defects in the graphenic sheets, ⅲ) Nano-clustering of quasi-metallic Na on micropores, and ⅳ) Solid-electrolyte-interphase (SEI) formation, including the related irreversible Na trapping. Besides, their state of charge dependence upon cycling is still widely discussed. [3] In this study, we attempt to elucidate the sodiation processes in a peanut shell-derived hard carbon anode. X-ray based techniques and vibrational spectroscopies are used to probe and clarify the structure/function correlation and the potential dependence of the sodiation processes. In-situ X-ray diffraction (XRD) is performed to evaluate the effect of Na ion intercalation on the interlayer distance among graphenic sheets. The carbon structure changes occurring in the electrode’s bulk and surface a upon sodiation are investigated by in-situ Raman spectroscopy. X-ray absorption (XAS), emission (XES), and photoelectron (XPS) spectroscopies in the soft and tender X-ray regimes are employed to reveal the formation and evolution of the SEI upon cycling, complemented by ex-situ attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy to identify the chemical species generated. Additionally, resonant inelastic X-ray scattering (RIXS) measurements at the C K-edge provide supplementary information about the Na-insertion mechanism into the anode structure due to its excellent atom-specificity and mapping of the C band structure at different (dis)charge stages. Overall, a direct relation between structural properties of hard carbon and its sodiation mechanism is proposed, paving the way for a rational design of high-performance hard carbon anodes. Reference s : [1] V. Palomares, P. Serras, I. Villaluenga, K. B. Hueso, J. Carretero-Gonzalez, T. Rojo, Energy Environ. Sci. 2012, 5, 5884. [2] S. Roberts, E. Kendrick, Nanotechnol. Sci. Appl. 2018, 11, 23. [3] X. Dou, I. Hasa, D. Saurel, C. Vaalma, L. Wu, D. Buchholz, D. Bresser, S. Komaba, S. Passerini, Materials Today, 2019, 23, 87. [4] D. Saurel, B. Orayech, B. Xiao, D. Carriazo, X. Li, T. Rojo, Adv. Energy Mater. 2018, 8, 1703268.

Essentials Standardization of extracellular vesicle (EV) measurements by flow cytometry needs improvement. Hollow organosilica beads were prepared, characterized, and tested as reference particles. Light scattering properties of hollow beads resemble that of platelet-derived EVs. Hollow beads are ideal reference particles to standardize scatter flow cytometry research on EVs. Summary Background The concentration of extracellular vesicles (EVs) in body fluids is a promising biomarker for disease, and flow cytometry remains the clinically most applicable method to identify the cellular origin of single EVs in suspension. To compare concentration measurements of EVs between flow cytometers, solid polystyrene reference beads and EVs were distributed in the first ISTH-organized interlaboratory comparison studies. The beads were used to set size gates based on light scatter, and the concentration of EVs was measured within the size gates. However, polystyrene beads lead to false size determination of EVs, owing to the mismatch in refractive index between beads and EVs. Moreover, polystyrene beads gate different EV sizes on different flow cytometers. Objective To prepare, characterize and test hollow organosilica beads (HOBs) as reference beads to set EV size gates in flow cytometry investigations. Methods HOBs were prepared with a hard template sol-gel method, and extensively characterized for morphology, size, and colloidal stability. The applicability of HOBs as reference particles was investigated by flow cytometry with HOBs and platelet-derived EVs. Results HOBs proved to be monodisperse with a homogeneous shell thickness. Two-angle light-scattering measurements by flow cytometry confirmed that HOBs have light-scattering properties similar to those of platelet-derived EVs. Conclusions Because the structure and light-scattering properties HOBs resemble those of EVs, HOBs with a given size will gate EVs of the same size. Therefore, HOBs are ideal reference beads with which to standardize optical measurements of the EV concentration within a predefined size range.

Many low-density nanoparticles show a radial inner structure. This work proposes a novel approach to contrast variation with small-angle X-ray scattering based on the constitution of a solvent density gradient in a glass capillary in order to resolve this internal morphology. Scattering curves of a polymeric core–shell colloid were recorded at different suspending medium contrasts at the four-crystal monochromator beamline of PTB at the synchrotron radiation facility BESSY II. The mean size and size distribution of the particles as well as an insight into the colloid electron density composition were determined using the position of the isoscattering points in the Fourier region of the scattering curves and by examining the Guinier region in detail. These results were corroborated with a model fit to the experimental data, which provided complementary information about the inner electron density distribution of the suspended nanoparticles.

When nanoparticles are introduced into biological media, they acquire a protein corona whose characterization is key to the full exploitation of their application. Here, we compare the use of dynamic light scattering (DLS), differential centrifugal sedimentation (DCS) and small angle X-ray scattering (SAXS) for the characterization of 105 nm polystyrene particles coated with proteins. All techniques measured an increase in protein shell thickness with increasing concentration of the proteins during incubation with the nanoparticles. DLS measurements were the highest in value, indicating a possible effect of particle agglomeration on the accuracy of the technique. DCS accuracy critically depended on the knowledge of the protein shell density, but allowed estimation of the effective density of the polymer core and protein shell. SAXS measurements proved powerful for understanding the complex core/shell structure of the particles, but model refinement of SAXS and DCS is required for the full consistency of the techniques

The continuously growing complexity of nanodrugs urges for complementary characterization techniques which can elude the current limitations. In this paper, the applicability of continuous contrast variation in small-angle X-ray scattering (SAXS) for the accurate size determination of a complex nanocarrier is demonstrated on the example of PEGylated liposomal doxorubicin (Caelyx). The mean size and average electron density of Caelyx was determined by SAXS using a gradient of aqueous iodixanol (Optiprep), an iso-osmolar suspending medium. The study is focused on the isoscattering point position and the analysis of the Guinier region of the scattering curves recorded at different solvent densities. An average diameter of (69 ± 5) nm and electron density of (346.2 ± 1.2) nm(-3) were determined for the liposomal formulation of doxorubicin. The response of the liposomal nanocarrier to increasing solvent osmolality and the structure of the liposome-encapsulated doxorubicin after the osmotic shrinkage of the liposome are evaluated with sucrose contrast variation in SAXS and wide-angle X-ray scattering (WAXS). In the case of using sucrose as contrast agent, a clear osmolality threshold at 670 mOsm kg(-1) was observed, above which the liposomal drug carriers start to shrink, though preserving the intraliposomal doxorubicin structure. The average size obtained by this technique is smaller than the value measured by dynamic light scattering (DLS), though this difference is expected due to the hydrodynamic size of the PEG moieties attached to the liposomal surface, which are not probed with solvent contrast variation in SAXS. The advantages and drawbacks of the proposed technique are discussed in comparison to DLS, the most frequently used sizing method in nanomedicine.

Resonant inelastic X-ray scattering (RIXS) and X-ray absorption (XA) experiments at the iron L- and nitrogen K-edge are combined with high-level first principles restricted active space self-consistent field (RASSCF) calculations for a systematic investigation of the nature of the chemical bond in potassium ferrocyanide in aqueous solution. The atom- and site-specific RIXS excitations allow for direct observation of ligand-to-metal (Fe L-edge) and metal-to-ligand (N K-edge) charge transfer bands and thereby evidence for strong {\sigma}-donation and {\pi}-back-donation. The effects are identified by comparing experimental and simulated spectra related to both the unoccupied and occupied molecular orbitals in solution.

The underlying beneficial mechanism of heavy alkali postdeposition treatment (PDT) of Cu(In,Ga)Se2 thin-film solar cell absorbers that led to new record efficiencies in recent years is studied using photoelectron spectroscopy. Excitation energies between 40.8 eV and 6 keV were used to examine the near-surface region of Cu(In,Ga)Se2 thin-film solar cell absorbers that underwent NaF and combined NaF/RbF PDT. The already Cu-deficient surface region after NaF PDT, which is modeled as a Cu:(In + Ga):Se = 1:5:8 phase, shows further depletion after NaF/RbF PDT and seems to incorporate some Rb. Additionally, we have found strong indications for the NaF/RbF PDT-induced formation of a Rb-In-Se-type compound with a 1:1:2 stoichiometry partially covering the absorber surface. The electronic Cu(In,Ga)Se2 structure is modified due to the RbF treatment, with a pronounced shift in the valence band maximum away from the Fermi level in the immediate vicinity of the surface.