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Sustainable N‐doped carbon aerogels were synthesized by a scalable hydrothermal approach using low‐cost and abundant precursors such as glucose and ovalbumin. By adjusting the pyrolysis temperature (900–1500 °C), the surface chemistry, porosity and conductivity of these aerogels could be optimized for the design of Pt‐based oxygen reduction reaction (ORR) catalysts with high Pt loading (40 wt % Pt) and improved stability. Pt nanoparticle deposition was realized by wet impregnation followed by thermal reduction and their size and distribution was found to strongly depend on the surface chemistry of the carbon aerogels. The catalysts' activities and stabilities, determined by rotating disc electrode measurements in HClO4, were found to strongly depend on the pyrolysis temperature of the N‐doped carbon aerogel supports. While the mass activity decreased with increasing temperature, in line with a decreasing ECSA related to an increase in Pt nanoparticle size, the long‐term stability of the catalysts, as revealed by accelerated stress tests for carbon support degradation (10,000 cycles), increased with increasing pyrolysis temperature, in line with increasing Pt nanoparticle sizes and increasing graphitization of the carbon aerogel supports. Most importantly, the catalyst derived from aerogels pyrolyzed at 1000 °C achieved a good compromise between activity and stability and revealed a superior ORR activity after the accelerated stress test in comparison to a commercially available Pt/C reference catalyst (40 wt % Pt). [ABSTRACT FROM AUTHOR]

Zinc oxide thin films are fabricated by controlled oxidation of sputtered zinc metal films on a hotplate in air at temperatures between 250 and 450 °C. The nanocrystalline films possess high relative densities and show preferential growth in (100) orientation. Integration in thin‐film transistors reveals moderate charge carrier mobilities as high as 0.2 cm2 V−1s−1. The semiconducting properties depend on the calcination temperature, whereby the best performance is achieved at 450 °C. The defect structure of the thin ZnO film can be tracked by Doppler‐broadening positron annihilation spectroscopy as well as positron lifetime studies. Comparably long positron lifetimes suggest interaction of zinc vacancies (VZn) with one or more oxygen vacancies (VO) in larger structural entities. Such VO‐VZn defect clusters act as shallow acceptors, and thus, reduce the overall electron conductivity of the film. The concentration of these defect clusters decreases at higher calcination temperatures as indicated by changes in the S and W parameters. Such zinc oxide films obtained by conversion of metallic zinc can also be used as seed layers for solution deposition of zinc oxide nanowires employing a mild microwave‐assisted process. The functionality of the obtained nanowire arrays is tested in a UV sensor device. The best results with respect to sensor sensitivity are achieved with thinner seed layers for device construction. [ABSTRACT FROM AUTHOR]

Keywords: defect structures; nanostructures; positron annihilation; thin-film transistors; UV sensors; zinc oxide EN defect structures nanostructures positron annihilation thin-film transistors UV sensors zinc oxide 5307 5307 1 03/24/21 20210322 NES 210322 B Detection of combined defect cluster sites in zinc oxide b : Oxidation of plasma sputtered zinc generates zinc oxide films in which Doppler broadening positron annihilation spectroscopy (PAS) and positron annihilation life-time studies (PALS) make it possible to detect oxygen vacancies (Vo) that are in close proximity to zinc vacancies (VZn). Front Cover: Zinc Oxide Defect Microstructure and Surface Chemistry Derived from Oxidation of Metallic Zinc: Thin-Film Transistor and Sensor Behavior of ZnO Films and Rods (Chem. Eur. J. 17/2021) Defect structures, nanostructures, positron annihilation, thin-film transistors, UV sensors, zinc oxide. [Extracted from the article]

• A thin PBSAC layer on the permeate side of UF removes steroid hormones effectively. • A millimetric packed-layer reaches estradiol removal higher than 99%. • The use of smaller PBSAC particles within the layer enhances the adsorption kinetics significantly. • Estradiol concentration can be reduced to value lower than the proposed drinking water guideline. The European Union has proposed the value of 1 ng L−1 as a drinking water quality standard for estradiol. With conventional technologies only partially removing estradiol, the investigation of novel alternatives is more than ever required. Tagliavini and Schäfer proposed that the use of a thin activated carbon layer combined with a membrane is worth considering. In this work, the process was further advanced through a systematic investigation of the role of activated carbon size, activation and surface chemistry on the removal of estradiol. The use of smaller carbon particles allows reaching the ambitious target value of 1 ng L−1 in a millimetric layer. Further, adsorption kinetic enhancement by increasing the oxygen content on the carbon improves the removal from 96 to 99 % (for a layer of 2 mm) for OH-containing pollutants such as estradiol. High removal, together with low pressure and no by-product formation, are characteristics that make the UF-PBSAC a promising and competitive approach. Image, graphical abstract [ABSTRACT FROM AUTHOR]