Search

Quantification in 2D LA-ICP-MS mapping generally requires matrix-matched standards to minimize issues related to elemental fractionation. In addition, internal standardization is commonly applied to correct for instrumental drift and fluctuation, whereas also differences in ablated mass can be rectified for samples that cannot be sectioned and subjected to total ablation. However, it is crucial that the internal standard element is homogeneously distributed in the sample and that the laser light absorptivity is uniform over the surface. As in practice these requirements are often not met, this work will focus on correction of ablation rate differences within/between samples and standards by normalizing the element maps using the associated ablation volume per pixel as measured by optical profilometry. Due to the volume correction approach the element concentrations are no longer defined as mass per mass concentrations (in μg g−1) but by mass per volume concentrations (in μg cm−3), which can be interconverted in case matrix densities are known. The findings show that ablation volume-aided calibration yields more accurate element concentrations in 2D LA-ICP-MS maps for a decorative glass with highly varying elemental concentrations (murrina). This research presents a warning that if there are variations in ablation rates between samples and standards within and across matrices, even when their sensitivities are the same, generic LA-ICP-MS calibration protocols may not accurately depict the actual element concentrations. [Display omitted] • We present a method to rectify ablation volume discrepancies in LA-ICP-MS mapping. • Optical profilometry was used to quantify the ablated volume per pixel. • Implementation led to more accurate element concentrations in a murrina. • The validity was confirmed through alternative measurement techniques. [ABSTRACT FROM AUTHOR]

An abstract of the paper "Nonclassical Inclusion Bodies in Escherichia Coli," by Marjan Bele, Viktor Menart, and colleagues, is presented.

Water splitting in acidic media is a sustainable and efficient new way to produce hydrogen fuel. However, the main bottleneck preventing the wider use of electrolyzers is still the oxygen evolution reaction (OER). Currently, the best electrocatalysts for OER are Ir-based materials, but the mechanistic details are still not fully understood. In this work, we investigate the similarities and differences in the OER mechanism of three different Ir-based catalysts, namely Vulcan carbon-supported and unsupported metallic Ir and rutile IrO 2 nanoparticles, and the process of Ir activation. For this purpose, we use large amplitude AC Voltammetry to distinguish between capacitive and faradaic processes. To quantify the data, we also use a mechanistic fit of the resolved harmonics. We show that all catalysts share the same OER mechanism but require different amounts of activation cycles. We have found three intrinsic properties, which can adequately describe a material for electrocatalysis. First is the activation threshold number (ATN), second is the current normalized to the number of active sites (intrinsic current), and lastly the mass normalized active site density. It was found that Ir on Vulcan has an intrinsic activity at least 3 times higher than the other two materials under consideration, as well as having the highest active site density. From the model fits we can also gain further insight into the mechanistic details for each material. For metallic Ir samples, the rate-limiting step is shown to be water adsorption, whereas for IrO 2 the bottleneck is the inherently slower kinetics. This also indicates that IrO 2 does not produce the same IrOH as Ir metal and therefore has different intrinsic properties. This study provides new insights into the intrinsic properties of different Ir nanocatalysts and highlights a general approach to studying the reaction mechanisms and intrinsic properties of electrocatalysts. [ABSTRACT FROM AUTHOR]

In the past, platinum–copper catalysts have proven to be highly active for the oxygen reduction reaction (ORR), but transferring the high activities measured in thin-film rotating disk electrodes (TF-RDEs) to high-performing membrane electrode assemblies (MEAs) has proven difficult due to stability issues during operation. High initial performance can be achieved. However, fast performance decay on a timescale of 24 h is induced by repeated voltage load steps with H2/air supplied. This performance decay is accelerated if high relative humidity (>60% RH) is set for a prolonged time and low voltages are applied during polarization. The reasons and possible solutions for this issue have been investigated by means of electrochemical impedance spectroscopy and distribution of relaxation time analysis (EIS–DRT). The affected electrochemical sub-processes have been identified by comparing the PtCu electrocatalyst with commercial Pt/C benchmark materials in homemade catalyst-coated membranes (CCMs). The proton transport resistance (Rpt) increased by a factor of ~2 compared to the benchmark materials. These results provide important insight into the challenges encountered with the de-alloyed PtCu/KB electrocatalyst during cell break-in and operation. This provides a basis for improvements in the catalysts' design and break-in procedures for the highly attractive PtCu/KB catalyst system. [ABSTRACT FROM AUTHOR]

LiMnPO4 particles with a size of 15-20 nm embedded in a carbon matrix are prepared as cathode materials for Li ion batteries from solutions of Mn(OAc)2, citric acid, and H3PO4 (Ar, 700 °C, 1 h) avoiding the presence of Li in the first step, followed by mixing the product with LiOH and thermal treatment at 700 °C for 12 h in Ar. [ABSTRACT FROM AUTHOR]

Thermochromic composites of benzofluoran dye, bisphenol A developer and octadecanol solvent were investigated to analyse how different molar ratios of developer influences the structural, optical and thermal properties. Increasing the amount of developer gives stronger absorption in the visible region and larger colour contrast between coloured and discoloured states. The colour clearing temperature of all studied composites is well below their melting point and the phase transitions are influenced only little by the content of the developer. The crystalline structure is fully controlled by the solvent; it changes from the γ phase to the liquid at heating and returns through the rotator phase into the γ phase at cooling. Crystallinity of the composites diminishes with the content of the developer, causing increased scattering of light. The dye: developer molar ratio equal to 1:3 was determined to be large enough to open lactone ring in all dye molecules. Colour hysteresis of such composites shrinks to practically single sigmoidal curve whereas the colour contrast still increases with higher amount of the developer. This effect could be attributed to developer – solvent interactions in a composite with lower crystallinity. [ABSTRACT FROM AUTHOR]

Abstract: A general method for tracking morphological surface changes on a nanometer scale with scanning electron microscopy (SEM) is introduced. We exemplify the usefulness of the method by showing consecutive SEM images of an identical location before and after the electrochemical and thermal treatments of platinum-based nanoparticles deposited on a high surface area carbon. Observations reveal an insight into platinum based catalyst degradation occurring during potential cycling treatment. The presence of chloride clearly increases the rate of degradation. At these conditions the dominant degradation mechanism seems to be the platinum dissolution with some subsequent redeposition on the top of the catalyst film. By contrast, at the temperature of 60°C, under potentiostatic conditions some carbon corrosion and particle aggregation was observed. Temperature treatment simulating the annealing step of the synthesis reveals sintering of small platinum based composite aggregates into uniform spherical particles. The method provides a direct proof of induced surface phenomena occurring on a chosen location without the usual statistical uncertainty in usual, random SEM observations across relatively large surface areas. [Copyright &y& Elsevier]

Titanium oxynitride carbon composite nanofibers (TiON/C-CNFs) were synthesised with electrospinning and subsequent heat treatment in ammonia gas. In situ four-probe electrical conductivity measurements of individual TiON/C-CNFs were performed. Additionally, the TiON/C-CNFs were thoroughly analysed with various techniques, such as X-ray and electron diffractions, electron microscopies and spectroscopies, thermogravimetric analysis and chemical analysis to determine the crystal structure, morphology, chemical composition, and N/O at. ratio. It was found that nanofibers were composed of 2–5 nm sized titanium oxynitride (TiON) nanoparticles embedded in an amorphous carbon matrix with a small degree of porosity. The average electrical conductivity of a single TiON/C-CNF was 1.2 kS/m and the bulk electrical conductivity of the TiON/C-CNF fabric was 0.053 kS/m. From the available data, the mesh density of the TiON/C-CNF fabric was estimated to have a characteristic length of 1.0 µm and electrical conductivity of a single TiON/C-CNF was estimated to be from 0.45 kS/m to 19 kS/m. The electrical conductivity of the measured TiON/C-CNFs is better than that of amorphous carbon nanofibers and has ohmic behaviour, which indicates that it can effectively serve as a new type of support material for electrocatalysts, batteries, sensors or supercapacitors. [ABSTRACT FROM AUTHOR]

Abstract: Two stable modifications of A3V2(PO4)3 (A = Na or Li) were synthesized by citric acid assisted modified sol–gel synthesis. The obtained samples were phase pure Li3V2(PO4)3 and Na3V2(PO4)3 materials embedded in a carbon matrix. The samples were tested as half cells against lithium or sodium metal. Both samples delivered about 90 mAh g−1 at a C/10 cycling rate. The change of vanadium oxidation state and changes in the local environment of redox center for both materials were probed by in-situ X-ray absorption spectroscopy. Oxidation state of vanadium was determined by energy shift of the absorption edge. The reversible change of valence from trivalent to tetravalent oxidation state was determined in the potential window used in our experiments. Small reversible changes in the interatomic distances due to the relaxation of the structure in the process of alkali metal extraction and insertion were observed. Local environment (vanadium–oxygen bond distances) after 1st cycle were found to be the same as in the starting material. Both structures have been found very rigid without significant changes during alkali metal extraction. [Copyright &y& Elsevier]

Abstract: We report on the synthesis of magnetic iron oxide particles; study of the particles’ formation was undertaken to investigate conditions of precipitation in order to apply it efficiently to cellulose fibre coating procedures. Synthesis of magnetic particles was performed, comprised of variations of molar concentrations of precursor solutions as well as different addition protocols of reactants into the reaction system. This allowed us to investigate the formation of iron oxide particles from different starting points. Following the synthesis, an evaluation of particles’ formation in different stages of synthesis procedure i.e. at different pH values and analysis of particles’ properties was carried out. Structural properties (crystallinity, size of the single magnetite crystals), their magnetic and colloidal properties were correlated with the synthesis procedure used. Procedure with controlled addition of ammonium hydroxide solution into a solution of precursor iron salts results in magnetic particles with largest crystallite size and the most intense X-ray diffraction patterns. Size and crystallinity of formed particles are also dependent upon the molar concentrations of Fe2+ and Fe3+ ions. Highest values of saturation magnetization are again exhibited by particles, produced with controlled addition of catalyst into a solution of precursor, a consequence of their ordered structure, which also favourably influences their colloidal properties when dispersed in an aqueous-based ferrofluid. Gained insight of the presented synthesis study will prove useful when in situ precipitation of magnetic iron oxide particles will be used for the preparation of magnetic solid cellulose substrates, since it will allow for the optimal adjustment of process conditions. [Copyright &y& Elsevier]

The authors' intention was to prepare nanometer-sized zinc-phosphate nanoparticles that would be capable of binding histidine-rich TNF-α analogs onto their surface via a coordinative bond. Zinc-phosphate nanoparticles with a size of around 60 nm were prepared by a wet precipitation method and characterized using SEM, EDX, XRD, and DLS. First, BSA was bound as a testing protein, afterward two TNF-α analogs with decreased activity were bound to the described nanoparticles. The efficiency of binding and the existence of coordinative bond were confirmed with SDS-PAGE analysis. During binding, particle storage, and release experiments, the prepared TNF-α analogs retained their biological activity-hence the epitopes necessary for formation of antibodies stayed intact. The particle size did not change within a period of 2 weeks. No significant agglomeration was observed, the particles could be quickly dispersed in ultrasound. The present nanoparticles and the general approach of coordinative binding are widely applicable for natural and engineered histidine-rich proteins. The nanoparticles bearing appropriate TNF-α analogs could also be potentially used for active immunotherapy to tackle the chronic inflammatory diseases associated with pathogenically elevated levels of TNF-α. [ABSTRACT FROM AUTHOR]

The surface of freshly etched copper and bronze samples was modified by immersion in ethanol solutions of myristic (tetradecanoic) acid. Modification resulted in the formation of hydrophobic layers with contact angles up to 141°. Two kinds of surface structure were observed. The modified surface of copper was covered by a uniform layer containing nano-grains or knitted-like structure, whereas the modified surface of bronze was covered by a layer with lamellate patterns and nano-grains. The corrosion properties of bare and modified copper and bronze surfaces were tested by potentiodynamic polarization experiments in 0.014 M Na2SO4 + 0.024 M NaHCO3 solution. The deduced effectiveness of corrosion inhibition by the modified layers on copper and bronze was up to 97 and 68%, respectively. Modification of the surface by immersion in an ethanol solution of myristic acid appears to be a promising treatment for improving the corrosion resistance of copper. The same treatment was not very effective when used on bronze. [ABSTRACT FROM AUTHOR]

Abstract: Bifunctional nanocomposites possessing superparamagnetism and traceability with optical methods were prepared. The superparamagnetic properties were achieved by introducing highly concentrated, ca. 13nm-sized maghemite (γ-Fe2O3) nanoparticles into a silica matrix based on tetraethylorthosilicate (TEOS) and bis-1,2-(triethoxysilyl)ethane (BTSE). Traceability was attained by simultaneously incorporating a small amount of rhodamine 6G fluorescent dye into the same silica matrix. Agglomeration of the highly concentrated maghemite nanoparticles during the preparation procedure was prevented by pre-coating them with a 1–2nm thick silica layer. The nanocomposites exhibited a relatively high magnetization of ∼20emu/g. Superparamagnetism was demonstrated using ZFC and FC measurements. Although the presence of the nanoparticles modified the transparency of the pristine silica matrix, we show that the incorporated rhodamine 6G exhibits a well-resolved, blue-shifted peak in the fluorescence spectrum, with a maximum at about 552nm. The bifunctionality of the present nanocomposites could be interesting for the preparation of similar materials for biomedical applications. [Copyright &y& Elsevier]

Photocatalysts can be used both for air cleaning and solar energy harvesting through water splitting. However, pure TiO 2 photocatalysts are often inefficient and therefore co-catalysts are needed to improve the yield. To achieve this goal, we prepared TiO 2 and deposited Pt, Ir and Ru co-catalysts on its surface. Two base TiO 2 nanoparticles were used: P25 and rutile TiO 2 synthesized via hydrothermal method. Co-catalysts were deposited by wet impregnation technique using single element and a combination of two elements (Pt and Ir or Pt and Ru), followed by annealing in either air or H 2 /Ar. Annealing in reducing atmosphere increased the photocatalytic activity of oxidation of isopropanol compared to annealing in air. We demonstrated a clear influence of the co-catalysts on the photocatalytic degradation of isopropanol and on electrochemical water-splitting reaction. The platinum-containing samples showed the best HER activity. • TiO 2 deposited with single co-catalysts (Pt, Ir, Ru) and their pairs (Pt/Ir, Pt/Ru). • Rutile with co-catalyst annealed in H 2 /Ar shows remarkably increased activity. • Rutile with Pt shows the highest activity in hydrogen evolution reaction (HER). • The deposited co-catalysts for all metals were in the 2–4 nm size range. [ABSTRACT FROM AUTHOR]

In the future, low-temperature proton exchange membrane fuel cells (PEMFC), together with batteries, are expected to compete and eventually replace conventional combustion engines in the automotive industry. Currently, the most promising strategy towards cost-effective and highly-active oxygen reduction reaction (ORR) electrocatalysts seems to be alloying of Pt with less expensive and less noble 3d transition metals (Cu, Co and Ni, ...). A crucial issue to be resolved in the near future is, however, to bridge the gap between the remarkable activities measured on the laboratory scale with thin film rotating disk electrode (TF-RDE) and the industrial membrane electrode assembly (MEA). In the case of Pt-Cu alloy, one of the major reasons for this difficulty is inadequate removal of unstable Cu or in other words, improper 'activation'. Inadequately removed Cu can act as an impurity by poisoning the Pt surface via the well-known underpotential deposition (UPD) interaction, resulting in the inhibition of ORR performance. Due to highly favourable experimental conditions, in-situ electrochemical activation (in-situ EA) in TF-RDE setup masks many of the issues one experiences when trying to do the same ex-situ. Thus, matching the ORR performance obtained after in-situ EA with ex-situ CA in the case of Pt-Cu system has not been properly addressed so far. Based on a deeper understanding of in-situ EA of our in-house designed Pt-Cu/C electrocatalyst we here demonstrate development of carbon monoxide (CO) assisted ex-situ CA method. By using this gram scale ex-situ CA method, we for the first time show that a Pt-Cu system can achieve very high ORR performances in TF-RDE setup without any need for the use of in-situ EA. Image 1 [ABSTRACT FROM AUTHOR]

Achieving high durability of the polymer electrolyte membrane (PEM) fuel cell catalysts remains a major challenge. While most of the research focuses on the active phase, carbon support remains overlooked. In this study durability of carbon support materials for Pt alloy nanoparticles is critically evaluated. First graphene derivative (GD) based carbon supports with different chemical properties are prepared and utilized along with widely used commercial carbon black (CB) material. High-temperature electrochemical accelerated degradation tests (HT-ADTs) combined with X-ray photoelectron spectroscopy (XPS) show that the total amount of oxygen functionalities, the type of oxygen functionalities, and sp 2 carbon content play a crucial role in carbon support durability. The observations were confirmed with the direct online measurements of carbon corrosion via an advanced in-situ technique – an electrochemical cell coupled with a mass spectrometer (EC-MS). We report that increasing the content of sp 2 carbon and decreasing carboxyl functional groups have the most beneficial effect on stability. The study provides important guidelines for tailoring the carbon support properties and their relationship to the durability of the electrocatalyst, which could be crucial for producing more stable catalysts and achieving the Department of Energy's fuel cell system lifetime targets. Moreover, the innovative carbon design approach presented here could be applied in other fields such as batteries, supercapacitors, sensors and others. [Display omitted] • Graphene derivative support is more stable than carbon black support. • Oxygen functionalities and sp 2 carbon content in carbon support affect durability. • In-situ measurements using EC-MS confirm degradation of carbon support. • Findings offer carbon design relevant to batteries, supercapacitors, sensors and more. [ABSTRACT FROM AUTHOR]

Abstract The field of electrosynthesis has undergone a tremendous advancement in the past few decades by implementation of a catalyst at the nanoscale level. While significant knowledge on factors that influence the activity of specific reactions such as carbon-halogen (CX) bond activation has been gained, many questions regarding the stability and degradation of nanoparticles still remain unsolved. Through the combination of a three-folded advanced characterization approach that combines electrochemical, analytical and microscopic results we are for the first time able to map the degradation of nanoparticles for CX bond activation reaction. This methodology is exemplified on the stability study of the most active nanoparticles towards CX bond activation, namely Ag nanoparticles. Results indicate that under electrochemical operation conditions Ag nanoparticles degradation occurs via two mechanisms: (i) agglomeration/coalescence and (ii) electrochemical dissolution of nanoparticles in the electrolyte. Identification of these degradation mechanisms is a first step in the understanding and subsequently controlling the synthesis of active and sustainable catalyst towards industrial applications. [ABSTRACT FROM AUTHOR]

Dissolution of PtRu alloy nanoparticles on carbon support in acidic environment is qualitatively and quantitatively investigated using an advanced electrochemical technique: electrochemical flow cell (EFC) on-line coupled to inductively coupled plasma mass spectrometer (ICP-MS). Profound insights into potential-resolved corrosion stability of Ru-Pt alloy in the potential window from 0.05 to 1.6 V vs RHE are obtained. Compared to pure Pt the PtRu alloy is less stable due to destabilisation of Pt surface caused by Ru dissolution together with the presence of weaker Ru-Pt bonds. However, at high potentials (1.5 and 1.6 V) Pt gets stabilised, presumably via a Ru catalysed oxygen evolution reaction that acts as a cathodic protection. Both Ru and Pt dissolution are enhanced in the presence of methanol due to consumption of surface ruthenium oxides, presumably Ru 2 O 3 , by the methanol oxidation reaction and an inhibited redeposition of Pt ions due to surface blockage of CO. The results may be used as useful guidelines in designing future DMFC and PEMFC catalysts. [ABSTRACT FROM AUTHOR]

Ø Electrodeposition of chloride-free Cu NCs. Ø Activation of Cu NCs by appropriate electrochemical protocol. Ø Support effect towards the selective formation of methane on Cu NCs. Ø Influence of electrochemical double layer cycling and OCP in tuning the activity and selectivity of Cu NCs. Nowadays, electrochemical CO 2 reduction reaction (CO 2 RR) to value-added products represents one of the major challenges in electrocatalysis. Copper-based nanocubes (Cu NCs) have been proposed as the front-runner's catalyst for the production of C 2+ products at the industrial level. However, their selectivity (C 1 vs. C 2 product distribution) is rather complex depending on the dynamic structural transformations, the presence of mixed Cu+/Cu0 states, the microenvironment, and nanocatalyst-support interactions. Commonly, electrochemically-grown Cu NCs are prepared in the presence of chlorides that acts as a shaping agent. In this study, an optimized electrodeposition method for the synthesis of Cl−-free Cu 2 O nanocubes on a glassy carbon substrate with uniform size, shape, and loading is established. The successful preparation of chloride-free cuprous oxide nanocubes (Cu 2 O NCs) was confirmed with X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) analyses. We report how the electrochemical double-layer capacitance (EDLC) method for electrochemical surface area (ECSA) determination with(out) subsequent return to the open-circuit potential (OCP) conditions before electrolysis influences the CO 2 RR activity/selectivity. When Cu 2 O NCs are subjected to the EDLC method (often considered a non-invasive method) and exposed to the OCP before electrolysis, they become active for methane (CH 4) formation. Moreover, the influence of the potential window width (i.e. 200 and 400 mV) in which the EDLC-ECSA is employed and its correlations with the selectivity is presented. We underline the importance of the ECSA determination method and OCP on/off state as a triggering factor for reactivity/selectivity of particular Cu 2 O NCs for CO 2 RR and further emphasize the reconstructive nature of Cu 2 O NCs under CO 2 RR relevant conditions. [Display omitted] [ABSTRACT FROM AUTHOR]

Resveratrol-loaded alginate submicron particles were prepared by emulsification followed by external gelation. Scanning electron microscopy analysis of the air-dried and freeze-dried submicron particles demonstrated their spherical shape, from 100 nm to 600 nm in size. The encapsulation efficiency and loading for resveratrol were 24.5% (±1.6%) and 0.3% (±0.05%), respectively. The interactions between the encapsulated resveratrol and alginate were characterised by Fourier transform infrared spectroscopy and differential scanning calorimetry. The release from the alginate submicron particles was successfully described by the linear superimposition model, which allowed concluding that resveratrol transport is governed by Fick’s diffusion. The alginate submicron particles were prepared from materials that are considered as generally recognized as safe, and thus have good potential for use as a resveratrol delivery system in food products. [ABSTRACT FROM AUTHOR]

• Advanced identical location TEM was applied to TiON-supported Ir nanoparticles. • Efficient control over bubble accumulation during stability test was achieved. • Surface roughening revealed as the predominant degradation mechanism. • Oxidation suppression of ceramic-supported Ir was confirmed. The reduction of Ir loading and thus its efficient utilization in proton exchange membrane water electrolyzers (PEM-WE) inevitably depends on the rational design of novel nanomaterials. This, however, is not possible without the understanding of structure-stability interrelations and underlying mechanisms. When pursuing the reduction of Ir amount by its dispersion on ceramic materials, the interactions between the catalytically active sites and their support further complicate the already understood processes. In the present study, we use our unique approach, where we employ an Ir/TiON-based TEM grid and use it as a support system for the investigation of structural transformations of Ir nanoparticles. This was achieved by utilizing both the modified floating electrode (MFE) apparatus, which enables efficient bubble management during electrochemical experiments and identical-location scanning transmission electron microscopy (IL-STEM) approach. The analysis of obtained high-resolution images with in-house developed computer algorithms for image analysis reveals several processes with surface roughening being the predominant degradation mechanism. Additionally, suppressed oxidation tendency of supported Ir was directly confirmed. [Display omitted] [ABSTRACT FROM AUTHOR]

Energy-efficient photocatalytic CO 2 reduction (PCO 2 R) into sustainable solar fuels is a highly enticing challenge for simultaneous settling of energy and environmental issues. Herein, we illustrate the synthesis and photocatalytic performance of a judiciously designed plasmonic Au nanoparticles photodeposited on TiO 2 -decorated N-doped graphene (ANGT- x) heterostructure catalyst showing remarkably enhanced CO 2 reduction activity with high selectivity for methane production. Compared to typical binary Au-TiO 2 photocatalyst, the ANGT2 exhibited almost 60 times higher electron consumption rate (R electron) value ~ 742.39 µmol g−1h−1 for the reduced products, which, to the best of our knowledge is the highest PCO 2 R rate ever reported under comparable conditions. The superior performance of ANGT2 catalyst is attributed to the synergistic contributions from improved light absorbance, enhanced CO 2 uptake together with improved charge transfer kinetics and efficient suppression of photogenerated (e-h) recombination rate bestowed by seamless interfacial contact between Au NPs and N-graphene-TiO 2 components. [Display omitted] • We demonstrate a series of Au-TiO 2 decorated N-doped graphene successfully synthesized by multistep preparation process. • N-doped graphene based heterostructure composites demonstrated high efficiency for photocatalytic CO 2 reduction. • From the aspect of electron consumption rate for the reduced products, the value is 742.39 µmolg−1h−1 for ANGT2. • The achieved catalytic activity was ~4 and ~60 folds higher than that of ANGT0 and binary AT2 catalysts, respectively. • This kind of distinctive photocatalytic system has greatly overcome the drawbacks compared with single/multi components. [ABSTRACT FROM AUTHOR]

Abstract: A number of reports on potential toxicity of nanoparticles are available, but there is still a lack of knowledge concerning bioaccumulation. The aim of this work was to investigate how different sources of zinc, such as uncoated and unmodified ZnO nanoparticles, ZnCl2 in solution, and macropowder ZnO influence the bioaccumulation of this metal in the terrestrial isopod Porcellio scaber. After exposure to different sources of Zn in the diet, the amount of assimilated Zn in whole body, the efficiency of zinc assimilation, and bioaccumulation factors (BAFs) were assessed. The bioaccumulation potential of Zn was found to be the same regardless of Zn source. The amount of assimilated Zn and BAF were dose-dependent, and Zn assimilation efficiency was independent of exposure concentrations. The Zn assimilation capacity was found to be up to 16% of ingested Zn. It is known that as much as approximately 20% of Zn can be accreted from ZnO particles by dissolution. We conclude that bioaccumulation of Zn in isopods exposed to particulate ZnO depends most probably on Zn dissolution from ZnO particles and not on bioaccumulation of particulate ZnO. [Copyright &y& Elsevier]

Abstract: This paper shows, for the first time, that the electrophoretic deposition technique is able to selectively collect protein inclusion bodies (PBs) from the host bacteria suspensions. In the first step, zeta potential as a function of pH is carefully determined for both species involved. Based on the obtained dependencies, the pH of the mixture of PBs and bacteria is precisely adjusted and the electrophoretic experiment is carried out. We show that the efficiency of separation and the yield depends not only on the electrokinetic properties of given species but also on the electrode composition and surface morphology. The deposited species are easily removed by forced washing or reverse electric field. As a whole, the selectivity and the yields are higher than in most alternative state-of-the art techniques. [Copyright &y& Elsevier]

Abstract: We demonstrate, for the first time, a considerable electrochemical activity of two members of lithium transition element titanates: Li2FeTiO4 and Li2MnTiO4. Both materials consist of 10–20nm particles embedded in a conductive carbon coating. We show that not the coating but the small particle size is decisive for materials’ activity. Li2FeTiO4 shows a stable reversible capacity of up to 123mAhg−1 at C/20 and 60°C which is 83% of the theoretical value for exchange of 1 electron (148mAhg−1). Li2MnTiO4 could only be prepared in a nanosized form that contained about 30% of impurities. The capacity of the whole material (including impurities) is comparable to that of Li2FeTiO4 but the cycling stability is much poorer. In contrast to the Fe and Mn analogues, the third member of the titanate family, Li2NiTiO4, shows a good electrochemistry even when the particle size is much larger (about 100nm). During initial cycles at C/10 and 60°C, exchange of more than 1 electron per compound formula has been observed. The cycling stability at high temperatures, however, is poor. [Copyright &y& Elsevier]

Upon exposure to an electrochemical environment, structural properties of nanoparticulate electrocatalysts at the atomic scale are not stagnant but rather dynamic. These have a direct effect on catalysts' performance via structure-property relationships. The active surface structure is constantly changing via complex phenomena dependant on their nature and reaction conditions. State-of-the-art transmission electron microscopy (TEM) can already provide us with atomically precise structures of individual nanoparticles, which are a key to exploring structure-property relations. However, with the analysis of random nanoparticles with unknown structural history, it is impossible to realise the exact structural alternation mechanisms. In order to study these phenomena operando, in-situ or quasi-in-situ methods need to be developed and used. In the present study, we highlight a recently introduced methodological approach named modified floating electrode (MFE), which enables the assessment of (i) proton exchange membrane fuel cell (PEMFC) cathode oxygen reduction reaction (ORR) at the industry-relevant current densities and (ii) atomic-level structural changes of the same nanoparticle, via identical location scanning electron microscopy (SEM) and TEM approach (IL-SEM and IL-TEM), in one measurement. Careful analysis and comparison of atomically resolved high-resolution scanning TEM (HR-STEM) images of the same nanoparticle before and after MFE measurements were conducted via homemade microscopy image analysis algorithms. We reveal structural changes on the atomic-scale of the industrial benchmark Pt-Co nanoalloy ORR electrocatalyst upon exposure to electrochemical activation and high ORR current densities. Observing and comparing the detailed structure and morphology of the same nanoparticle reveals atomic-scale processes such as particle anisotropic etching and redeposition, besides other processes such as particle necking, anti-necking, pore formation, particle movement, coalescence, etc. The understanding of the dynamics behind these changes is crucial for the interpretation of ORR electrocatalyst's activity and stability. Our bottom-up approach enables direct investigation of nanoparticles' structure-stability relationships. [ABSTRACT FROM AUTHOR]

• An efficient TiO x N y electro catalyst was synthesized in the immobilized form. • In-depth characterization of the active titanium oxynitride catalyst was performed. • A continuous-flow microreactor was used to study phenol degradation. • Oxidation mechanism was proposed including contribution of Cl− reaction pathways. • Optimal reactor dimensions were determined by the model. In this study a novel titanium oxynitride electrocatalyst was synthesized and its electrocatalytic activity for the degradation of phenol was evaluated. A highly conductive and efficient Ti–O–N electrocatalyst was prepared in a three-step synthesis. A titanium coil was anodized to grow TiO 2 nanotubes, which were then annealed in air to convert the amorphous structure to anatase and afterwards annealed in ammonia to obtain the final Ti–O–N catalyst. This was characterized with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected-area electron diffraction (SAED). To evaluate its degradation capabilities, the electrocatalytic oxidation of the phenol was performed inside a coil-type electrocatalytic microreactor. Phenol conversions of up to 95% of the initial 0.4 mmol L–1 of phenol were achieved at the studied applied electric potentials (1–16 V), NaCl concentrations (0.51–5.12 g L–1) and flow rates(20–500 μL min–1). The mechanism of electrocatalytic oxidation was proposed in a three-dimensional reactor model that accurately describes the electrocatalytic degradation of phenol at the Ti–O–N anode in the presence of NaCl in the phenol solution. It was shown that both OH*– and OCl*–mediated reaction mechanisms contribute to the phenol's degradation, while at high NaCl concentrations (5 g L–1) the latter is dominant. In addition, the optimal reactor design is determined by studying the mass-transfer limitation with the model. [ABSTRACT FROM AUTHOR]

Nanoparticulate electrocatalysts for the oxygen reduction reaction are structurally diverse materials. Scanning transmission electron microscopy (STEM) has long been the go-to tool to obtain high-quality information about their nanoscale structure. More recently, its four-dimensional modality has emerged as a tool for a comprehensive crystal structure analysis using large data sets of diffraction patterns. In this study, we track the alternations of the crystal structure of individual carbon-supported PtCu 3 nanoparticles before and after fuel cell-relevant activation treatment, consisting of a mild acid-washing protocol and potential cycling, essential for forming an active catalyst. To take full advantage of the rich, identical location 4D-STEM capabilities, unsupervised algorithms were used for the complex data analysis, starting with k -means clustering followed by non-negative matrix factorization, to find commonly occurring signals within specific nanoparticle data. The study revealed domains with (partially) ordered alloy structures, twin boundaries, and local amorphization. After activation, specific nanoparticle surface sites exhibited a loss of crystallinity which can be correlated to the simultaneous local scarcity of the ordered alloy phase, confirming the enhanced stability of the ordered alloy during potential cycling activation conditions. With the capabilities of our in-house developed identical-location 4D-STEM approach to track changes in individual nanoparticles, combined with advanced data analysis, we determine how activation treatment affects the electrocatalysts' local crystal structure. Such an approach provides considerably richer insights and is much more sensitive to minor changes than traditional STEM imaging. This workflow requires little manual input, has a reasonable computational complexity, and is transferrable to other functional nanomaterials.

In the present work, we report on a synergistic relationship between platinum nanoparticles and a titanium oxynitride support (TiO x N y /C) in the context of oxygen reduction reaction (ORR) catalysis. As demonstrated herein, this composite configuration results in significantly improved electrocatalytic activity toward the ORR relative to platinum dispersed on carbon support (Pt/C) at high overpotentials. Specifically, the ORR performance was assessed under an elevated mass transport regime using the modified floating electrode configuration, which enabled us to pursue the reaction closer to PEMFC-relevant current densities. A comprehensive investigation attributes the ORR performance increase to a strong interaction between platinum and the TiO x N y /C support. In particular, according to the generated strain maps obtained via scanning transmission electron microscopy (STEM), the Pt-TiO x N y /C analogue exhibits a more localized strain in Pt nanoparticles in comparison to that in the Pt/C sample. The altered Pt structure could explain the measured ORR activity trend via the d-band theory, which lowers the platinum surface coverage with ORR intermediates. In terms of the Pt particle size effect, our observation presents an anomaly as the Pt-TiO x N y /C analogue, despite having almost two times smaller nanoparticles (2.9 nm) compared to the Pt/C benchmark (4.8 nm), manifests higher specific activity. This provides a promising strategy to further lower the Pt loading and increase the ECSA without sacrificing the catalytic activity under fuel cell-relevant potentials. Apart from the ORR, the platinum-TiO x N y /C interaction is of a sufficient magnitude not to follow the typical particle size effect also in the context of other reactions such as CO stripping, hydrogen oxidation reaction, and water discharge. The trend for the latter is ascribed to the lower oxophilicity of Pt-based on electrochemical surface coverage analysis. Namely, a lower surface coverage with oxygenated species is found for the Pt-TiO x N y /C analogue. Further insights were provided by performing a detailed STEM characterization via the identical location mode (IL-STEM) in particular, via 4DSTEM acquisition. This disclosed that Pt particles are partially encapsulated within a thin layer of TiO x N y origin., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

Aiming at speeding up the discovery and understanding of promising electrocatalysts, a novel experimental platform, i.e. , the Nano Lab , is introduced. It is based on state-of-the-art physicochemical characterization and atomic-scale tracking of individual synthesis steps as well as subsequent electrochemical treatments targeting nanostructured composites. This is provided by having the entire experimental setup on a transmission electron microscopy (TEM) grid. Herein, the oxygen evolution reaction nanocomposite electrocatalyst, i.e., iridium nanoparticles dispersed on a high-surface-area TiO x N y support prepared on the Ti TEM grid, is investigated. By combining electrochemical concepts such as anodic oxidation of TEM grids, floating electrode-based electrochemical characterization, and identical location TEM analysis, relevant information from the entire composite's cycle, i.e. , from the initial synthesis step to electrochemical operation, can be studied. We reveal that Ir nanoparticles as well as the TiO x N y support undergo dynamic changes during all steps. The most interesting findings made possible by the Nano Lab concept are the formation of Ir single atoms and only a small decrease in the N/O ratio of the TiO x N y -Ir catalyst during the electrochemical treatment. In this way, we show that the precise influence of the nanoscale structure, composition, morphology, and electrocatalyst's locally resolved surface sites can be deciphered on the atomic level. Furthermore, the Nano Lab 's experimental setup is compatible with ex situ characterization and other analytical methods, such as Raman spectroscopy, X-ray photoelectron spectroscopy, and identical location scanning electron microscopy, hence providing a comprehensive understanding of structural changes and their effects. Overall, an experimental toolbox for the systematic development of supported electrocatalysts is now at hand., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

A versatile approach to the production of cluster- and single atom-based thin-film electrode composites is presented. The developed TiO x N y -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 TiO 2 -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/TiO x N y -Ir interface as a result of the anodic oxidation mechanism. The developed TiO x N y -Ir catalyst exhibits very high oxygen evolution reaction activity in 0.1 M HClO 4 , reaching 1460 A g -1 Ir at 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., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

The design of catalysts with stable and finely dispersed platinum or platinum alloy nanoparticles on the carbon support is key in controlling the performance of proton exchange membrane (PEM) fuel cells. In the present work, an intermetallic PtCo/C catalyst is synthesized via double-passivation galvanic displacement. TEM and XRD confirm a significantly narrowed particle size distribution for the catalyst particles compared to commercial benchmark catalysts (Umicore PtCo/C). Only about 10% of the mass fraction of PtCo particles show a diameter larger than 8 nm, whereas this is up to or even more than 35% for the reference systems. This directly results in a considerable increase in electrochemically active surface area (96 m 2 g -1 vs. >70 m 2 g -1 ), which confirms the more efficient usage of precious catalyst metal in the novel catalyst. Single-cell tests validate this finding by improved PEM fuel cell performance. Reducing the cathode catalyst loading from 0.4 mg cm -2 to 0.25 mg cm -2 resulted in a power density drop at an application-relevant 0.7 V of only 4% for the novel catalyst, compared to the 10% and 20% for the commercial benchmarks reference catalysts., Competing Interests: The authors declare no competing financial interest., (This journal is © The Royal Society of Chemistry.)

Decreasing iridium loading in the electrocatalyst presents a crucial challenge in the implementation of proton exchange membrane (PEM) electrolyzers. In this respect, fine dispersion of Ir on electrically conductive ceramic supports is a promising strategy. However, the supporting material needs to meet the demanding requirements such as structural stability and electrical conductivity under harsh oxygen evolution reaction (OER) conditions. Herein, nanotubular titanium oxynitride (TiON) is studied as a support for iridium nanoparticles. Atomically resolved structural and compositional transformations of TiON during OER were followed using a task-specific advanced characterization platform. This combined the electrochemical treatment under floating electrode configuration and identical location transmission electron microscopy (IL-TEM) analysis of an in-house-prepared Ir-TiON TEM grid. Exhaustive characterization, supported by density functional theory (DFT) calculations, demonstrates and confirms that both the Ir nanoparticles and single atoms induce a stabilizing effect on the ceramic support via marked suppression of the oxidation tendency of TiON under OER conditions., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

Water electrolysis powered by renewables is regarded as the feasible route for the production of hydrogen, obtained at the cathode side through electrochemical hydrogen evolution reaction (HER). Herein, we present a rational strategy to improve the overall HER catalytic performance of Pt, which is known as the best monometallic catalyst for this reaction, by supporting it on a conductive titanium oxynitride (TiON x ) dispersed over reduced graphene oxide nanoribbons. Characterization of the Pt/TiON x composite revealed the presence of small Pt particles with diameters between 2 and 3 nm, which are well dispersed over the TiON x support. The Pt/TiON x nanocomposite exhibited improved HER activity and stability with respect to the Pt/C benchmark in an acid electrolyte, which was ascribed to the strong metal-support interaction (SMSI) triggered between the TiON x support and grafted Pt nanoparticles. SMSI between TiON x and Pt was evidenced by X-ray photoelectron spectroscopy (XPS) through a shift of the binding energies of the characteristic Pt 4f photoelectron lines with respect to Pt/C. Density functional theory (DFT) calculations confirmed the strong interaction between Pt nanoparticles and the TiON x support. This strong interaction improves the stability of Pt nanoparticles and weakens the binding of chemisorbed H atoms thereon. Both of these effects may result in enhanced HER activity., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

The lack of efficient and durable proton exchange membrane fuel cell electrocatalysts for the oxygen reduction reaction is still restraining the present hydrogen technology. Graphene-based carbon materials have emerged as a potential solution to replace the existing carbon black (CB) supports; however, their potential was never fully exploited as a commercial solution because of their more demanding properties. Here, a unique and industrially scalable synthesis of platinum-based electrocatalysts on graphene derivative (GD) supports is presented. With an innovative approach, highly homogeneous as well as high metal loaded platinum-alloy (up to 60 wt %) intermetallic catalysts on GDs are achieved. Accelerated degradation tests show enhanced durability when compared to the CB-supported analogues including the commercial benchmark. Additionally, in combination with X-ray photoelectron spectroscopy Auger characterization and Raman spectroscopy, a clear connection between the sp 2 content and structural defects in carbon materials with the catalyst durability is observed. Advanced gas diffusion electrode results show that the GD-supported catalysts exhibit excellent mass activities and possess the properties necessary to reach high currents if utilized correctly. We show record-high peak power densities in comparison to the prior best literature on platinum-based GD-supported materials which is promising information for future application., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

Pt-alloy (Pt-M) nanoparticles (NPs) with less-expensive 3d transition metals (M = Ni, Cu, Co) supported on high-surface-area carbon supports are currently the state-of-the-art (SoA) solution to reach the production phase in proton exchange membrane fuel cells (PEMFCs). However, while Pt-M electrocatalysts show promise in terms of increased activity for oxygen reduction reaction (ORR) and, thus, cost reductions from the significantly lower use of expensive and rare Pt, key challenges in terms of synthesis, activation, and stability remain to unlock their true potential. This work systematically tackles them with a combination of electrocatalyst synthesis and characterization methodologies including thin-film rotating disc electrodes (TF-RDEs), an electrochemical flow cell linked to an inductively coupled plasma mass spectrometer (EFC-ICP-MS), and testing in 50 cm 2 membrane electrode assemblies (MEAs). In the first part of the present work, we highlight the crucial importance of the chemical activation (dealloying) step on the performance of Pt-M electrocatalysts in the MEA at high current densities (HCDs). In addition, we provide the scientific community with a preliminary and facile method of distinguishing between a "poorly" and "adequately" dealloyed (activated) Pt-alloy electrocatalyst using a much simpler and affordable TF-RDE methodology using the well-known CO-stripping process. Since the transition-metal cations can also be introduced in a PEMFC due to the degradation of the Pt-M NPs, the second part of the work focuses on presenting clear evidence on the direct impact of the lower voltage limit (LVL) on the stability of Pt-M electrocatalysts. The data suggests that in addition to intrinsic improvements in stability, significant improvements in the PEMFC lifetime can also be obtained via the correct MEA design and applied limits of operation, namely, restricting not just the upper but equally important also the lower operation voltage., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

Degradation of carbon-supported Pt nanocatalysts in fuel cells and electrolyzers hinders widespread commercialization of these green technologies. Transition between oxidized and reduced states of Pt during fast potential spikes triggers significant Pt dissolution. Therefore, designing Pt-based catalysts able to withstand such conditions is of critical importance. We report here on a strategy to suppress Pt dissolution by using an organic matrix tris(aza)pentacene (TAP) as an alternative support material for Pt. The major benefit of TAP is its potential-dependent conductivity in aqueous media, which was directly evidenced by electrochemical impedance spectroscopy. At potentials below ∼0.45 V RHE , TAP is protonated and its conductivity is improved, which enables supported Pt to run hydrogen reactions. At potentials corresponding to Pt oxidation/reduction (>∼0.45 V RHE ), TAP is deprotonated and its conductivity is restricted. Tunable conductivity of TAP enhanced the durability of the Pt/TAP with respect to Pt/C when these two materials were subjected to the same degradation protocol (0.1 M HClO 4 electrolyte, 3000 voltammetric scans, 1 V/s, 0.05-1.4 V RHE ). The exceptional stability of Pt/TAP composite on a nanoscale level was confirmed by identical location TEM imaging before and after the used degradation protocol. Suppression of transient Pt dissolution from Pt/TAP with respect to the Pt/C benchmark was directly measured in a setup consisting of an electrochemical flow cell connected to inductively coupled plasma-mass spectrometry., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

A fast and facile pulse combustion (PC) method that allows for the continuous production of multigram quantities of high-metal-loaded and highly uniform supported metallic nanoparticles (SMNPs) is presented. Namely, various metal on carbon (M/C) composites have been prepared by using only three feedstock components: water, metal-salt, and the supporting material. The present approach can be elegantly utilized also for numerous other applications in electrocatalysis, heterogeneous catalysis, and sensors. In this study, the PC-prepared M/C composites were used as metal precursors for the Pt NPs deposition using double passivation with the galvanic displacement method (DP method). Lastly, by using thin-film rotating disc electrode (TF-RDE) and gas-diffusion electrode (GDE) methodologies, we show that the synergistic effects of combining PC technology with the DP method enable production of superior intermetallic Pt-M electrocatalysts with an improved oxygen reduction reaction (ORR) performance when compared to a commercial Pt-Co electrocatalyst for proton exchange membrane fuel cells (PEMFCs) application., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

The production of hydrogen via a proton-exchange membrane water electrolyzer (PEM-WE) is directly dependent on the rational design of electrocatalysts for the anodic oxygen evolution reaction (OER), which is the bottleneck of the process. Here, we present a smart design strategy for enhancing Ir utilization and stabilization. We showcase it on a catalyst, where Ir nanoparticles are efficiently anchored on a conductive support titanium oxynitride (TiON x ) dispersed over carbon-based Ketjen Black and covered by a thin layer of copper (Ir/CuTiON x /C), which gets removed in the preconditioning step. Electrochemical OER activity, stability, and structural changes were compared to the Ir-based catalyst, where Ir nanoparticles without Cu are deposited on the same support (Ir/TiON x /C). To study the effect of the sacrificial less-noble metal layer on the catalytic performance of the synthesized material, characterization methods, namely X-ray powder diffraction, X-ray photoemission spectroscopy, and identical location transmission electron microscopy were employed and complemented with scanning flow cell coupled to an inductively coupled plasma mass spectrometer, which allowed studying the online dissolution during the catalytic reaction. Utilization of these advanced methods revealed that the sacrificial Cu layer positively affects both Ir OER mass activity and its durability, which was assessed via S-number, a recently reported stability metric. Improved activity of Cu analogue was ascribed to the higher surface area of smaller Ir nanoparticles, which are better stabilized through a strong metal-support interaction (SMSI) effect., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

Achieving highly active and stable oxygen reduction reaction performance at low platinum-group-metal loadings remains one of the grand challenges in the proton-exchange membrane fuel cells community. Currently, state-of-the-art electrocatalysts are high-surface-area-carbon-supported nanoalloys of platinum with different transition metals (Cu, Ni, Fe, and Co). Despite years of focused research, the established structure-property relationships are not able to explain and predict the electrochemical performance and behavior of the real nanoparticulate systems. In the first part of this work, we reveal the complexity of commercially available platinum-based electrocatalysts and their electrochemical behavior. In the second part, we introduce a bottom-up approach where atomically resolved properties, structural changes, and strain analysis are recorded as well as analyzed on an individual nanoparticle before and after electrochemical conditions (e.g. high current density). Our methodology offers a new level of understanding of structure-stability relationships of practically viable nanoparticulate systems., Competing Interests: The authors declare no competing interests., (© 2021 The Author(s).)

Preparation of large quantities of high-performance supported Pt-alloy electrocatalysts is crucial for the faster development and implementation of low-temperature proton exchange membrane fuel cells (PEMFCs). One of the prospective nanofabrication synthesis methods is based on the galvanic displacement (GD) reaction. A facile, highly reproducible, gram scale, water-based double passivation GD method is now presented for the synthesis of carbon-supported Pt-M nanoparticles (M=Cu, Ni, Co). It offers great flexibility over the catalyst design, such as the choice of the sacrificial metal (M), variation of the chemical composition of alloy, variation of total metal loading (Pt+M) on carbon support, or even variation of the carbon support itself. The obtained Pt-alloy catalysts are several times more active compared to a Pt reference and exhibits better stability during accelerated degradation tests performed at 60 °C., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Microplastic fibers (MP) from textile weathering and washing are increasingly being recognized as environmental pollutants. The majority of studies on the bioavailability and effects of microplastic focused on small polystyrene spherical plastic particles, while less data are available for fibers and for other materials besides polystyrene. We investigated the ingestion and effects of ground polyethylene terephthalate (PET) textile microfibers (length range: 62-1400 μm, width 31-528 μm, thickness 1-21.5 μm) on the freshwater zooplankton crustacean Daphnia magna after a 48 h exposure and subsequent 24 h of recovery in MP free medium and algae. The majority of ingested fibers by D. magna were around 300 μm, but also some very large twisted MP fibers around 1400 μm were found inside the gut. Exposure to these fibers results in increased mortality of daphnids after 48 h only in the case where daphnids were not pre-fed with algae prior to experiment, but no effect was found when daphnids were fed before the experiments. Regardless of the feeding regime, daphnids were not able to recover from MP exposure after additional 24 h incubation period in a MP free medium with algae. The uptake and effects of PET textile MP on D. magna are presented here for the first time., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

In this study the performance enhancement effect of structural ordering for the oxygen reduction reaction (ORR) is systematically studied. Two samples of PtCu3 nanoparticles embedded on a graphitic carbon support are carefully prepared with identical initial composition, particle dispersion and size distribution, yet with different degrees of structural ordering. Thus we can eliminate all coinciding effects and unambiguously relate the improved activity of the ORR and more importantly the enhanced stability to the ordered nanostructure. Interestingly, the electrochemically induced morphological changes are common to both ordered and disordered samples. The observed effect could have a groundbreaking impact on the future directions in the rational design of active and stable platinum alloyed ORR catalysts.

A new type of carbon film electrode, composed of a thin layer of tightly packed carbon black (CB) nanoparticles deposited onto a gelatin-covered indium tin oxide/glass support using the surface-induced deposition (SID) approach, is presented. Some parameters of the novel SID method were optimized and the surface image and functionalization of the investigated carbon black film electrode (CBFE) was inspected by employing scanning electron microscopy and infrared spectroscopy. A cyclic voltammetry (CV) study was conducted in which the electron-transfer kinetics and CBFE interfacial characteristics were evaluated employing several selected reference redox systems, such as [Ru(NH(3))(6)](3+/2+), [Fe(CN)(6)](3-/4-) and Fe(3+/2+) in aqueous, and ferrocene/ferrocenium in acetonitrile media. CV recordings were also performed in order to compare the electrochemical behavior of the CBFE with that of some well-known and established bare carbon-based electrodes. In order to confirm the validity of the CB film preparation method, the electroanalytical performance of the proposed CBFE was examined by carrying out linear sweep voltammetry of ascorbic acid (AA), anodic stripping square-wave voltammetry of Cu(II) in acidic medium, and amperometric measurements of hydrogen peroxide under flow injection conditions. The sensing characteristics of the novel carbon film electrode, demonstrated in this preliminary study, comprise: (i) a wide working potential window ranging from +1.0 to -1.3 V (depending on the solution pH), (ii) a wide applicable pH range (at least from 2 to 12), (iii) low voltammetric background (<5 microA cm(-2)), (iv) a satisfactory linear voltammetric and amperometric response (r(2)>0.99) to various analytes, (v) good reproducibility (for example, r.s.d. of 2% in amperometric detection of H(2)O(2) and r.s.d. of 8.5% for electrode-to-electrode CV runs), and (vi) stable and fast current response (at least 100 CV runs with negligible change in CV response). The main advantages of the proposed CBFE originate from the unique CB film formation procedure that enables fast, simple, inexpensive and non-toxic CBFE preparation, which can find application in advanced electrochemical devices and is suitable for mass production.