Search results for "Note"

Influence of the U3O7 domain structure on cracking during the oxidation of UO2

2010

Abstract Cracking is observed when a UO 2 single crystal is oxidised in air. Previous studies led to the hypothesis that cracking occurs once a critical depth of U 3 O 7 oxidised layer is reached. We present some μ-Laue X-ray diffraction results, which evidence that the U 3 O 7 layer, grown by topotaxy on UO 2 , is made of domains with different crystalline orientations. This observation was used to perform a modelling of oxidation coupling chemical and mechanical parameters, which showed that the domain patterning induces stress localisation. This result is discussed in comparison with stress localisation observed in thin layer deposited on a substrate and used to propose an interpretation…

Efficient Monolithic Perovskite/Perovskite Tandem Solar Cells

2016

Thin-film solar cells suffer from various types of recombination, of which leakage current usually dominates at lower voltages. Herein, we demonstrate first a three-order reduction of the shunt loss mechanism in planar methylammonium lead iodide perovskite solar cells by replacing the commonly used hole transport layer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) with a better hole-selective polyarylamine. As a result, these cells exhibit superior operation under reduced light conditions, which we demonstrate for the extreme case of moonlight irradiance, at which open-circuit voltages of 530 mV can still be obtained. By the shunt removal we also observe the VOC to dro…

Electrosynthesis and electrochemistry

2015

Since the pioneering work of Kolbe, electrochemistry and electrosynthetic methods have been a part of the repertoire of the organic synthesis toolbox [1–2]. In general, only electrons are employed as reagents or the reagents are electrochemically regenerated. Consequently, waste can be avoided, and limited resources can be used in a careful and economic manner. Because alternative reaction pathways are employed by electrosynthetic methods, scarce and toxic elements can be replaced or are not required at all [3]. Moreover, in the foreseeable future regenerative sources of electricity, for example, photovoltaics and wind power, will provide a surplus of electricity as the current unsteady sup…

Initial approaches in benchmarking and round robin testing for proton exchange membrane water electrolyzers

2019

Abstract As ever-increasing amounts of renewable electricity enter the energy supply mix on a regional, national and international basis, greater emphasis is being placed on energy conversion and storage technologies to deal with the oscillations, excess and lack of electricity. Hydrogen generation via proton exchange membrane water electrolysis (PEMWE) is one technology that offers a pathway to store large amounts of electricity in the form of hydrogen. The challenges to widespread adoption of PEM water electrolyzers lie in their high capital and operating costs which both need to be reduced through R&D. An evaluation of reported PEMWE performance data in the literature reveals that there …

Correction to Fluorine and Gold: A Fruitful Partnership

2016

Free-Standing Mono layer Two-Dimensional Supramolecular Organic Framework with Good Internal Order

2015

Utilizing dynamic self-assembly and self-sorting to obtain large-area, molecularly precise monolayered structures represents a promising approach toward two-dimensional supramolecular organic frameworks (2D SOF) or 2D supramolecular polymers. So far, related approaches suffer from small domain sizes, fragility and weak long-range internal order. Here we report on the self-assembly of a host-guest enhanced donor-acceptor interaction, consisting of a tris(methoxynaphthyl)-substituted truxene spacer, and a naphthalene diimide substituted with N-methyl viologenyl moieties as donor and acceptor monomers, respectively, in combination with cucurbit[8]uril as host monomer toward monolayers of an un…

Strategies for Exploring Functions from Dynamic Combinatorial Libraries

2020

200 Years of Lithium and 100 Years of Organolithium Chemistry

2018

The element lithium has been discovered 200 years ago. Due to its unique properties it has emerged to play a vital role in industry, esp. for energy storage, and lithium-based products and processes support sustainable technological developments. In addition to the many uses of lithium in its inorganic forms, lithium has a rich organometallic chemistry. The development of organometallic chemistry has been hindered by synthetic problems from the start. When Wilhelm Schlenk developed the basic principles to handle and synthesize air- and moisture-sensitive compounds, the road was open to further developments. After more information was available about the stability and solubility of such comp…

Synthesis and characterization of new coordination compounds by the use of 2-pyridinemethanol and di- or tricarboxylic acids

2021

The development of synthetic approaches towards new coordination polymers has attracted significant interest due to their fascinating physical properties, as well as their use in a wide range of technological, environmental and biomedical applications. Herein, the initial combination of 2-pyridinemethanol (Hhmp) with 1,4-benzenedicarboxylic acid (H2bdc) or 1,3,5-benzenetricarboxylic acid (H3btc) has been proven a fruitful source of such new species providing access to five new coordination compounds, namely [M2(Hbtc)2(Hhmp)4]·DMF (M = CoII, 1·DMF;NiII, 2·DMF), [Ni(bdc)(Hhmp)2]n·4H2O (3·4H2O), [Zn2(bdc)(hmp)2]n·DMF (4·DMF) and [Fe3(bdc)3(Hhmp)2]n (5). 4·DMF and 5 are the first metal–organic …

Effect of the orientation on the photooxidation behaviour of polymer films

2016

Abstract The effect of the orientation on the photooxidation of polymers is quite controversial. Both improvement of the photo-resistance along the oriented direction and worsening of the photooxidation kinetic have been reported. In this work the effect of the orientation has been investigated on films of PE, PP and PET with different degree of orientation and crystallinity. The results show that the photo-stability, measured from the decay of the elongation at break curve as a function of the irradiation time, improves in the more oriented direction, but this is more and more relevant with increasing the crystallinity degree. It has been hypothesized that the reinforcing action of the ori…