Polymer electrolyte water electrolysis: Understanding the microstructure of a core-shell based anode catalyst layer
Reducing precious metal loading in the anodic catalyst layer (CL) is indispensable for lowering capital costs and enabling the widespread adoption of polymer electrolyte water electrolysis (PEWE). This work presents the first three-dimensional reconstruction of a TiO2-supported IrO2 based core shell catalyst layer, using high-resolution X-ray ptychographic tomography at cryogenic temperature of 90 K. The high data quality and phase sensitivity of the technique have allowed the reconstruction of all four phases namely pore space, IrO2, TiO2 support matrix and the ionomer network, the latter of which has proven to be a challenge in the past.
Dr Christian Wäckerlin is appointed as assistant professor at EPFL
Dr Christian Wäckerlin (*1983), currently Research and Teaching Associate at EPFL and Project Leader at the Paul Scherrer Institute (PSI), as Assistant Professor of Physics in the School of Basic Sciences. Christian Wäckerlin’s research focuses on nanoscience and quantum engineering.
X-rays look at nuclear fuel cladding with new detail
Micro-beam measurements at the Swiss Light Source SLS give insights into the crystal structure of hydrides that promote cracks in nuclear fuel cladding.
Laura Heyderman elected Royal Society Fellow
Laura’s nomination recognises almost 30 years of research into magnetic materials and magnetism on the nanoscale.
A deep look into hydration of cement
Researchers led by the University of Málaga show the Portland cement early age hydration with microscopic detail and high contrast between the components. This knowledge may contribute to more environmentally friendly manufacturing processes.
Apochromatic X-ray focusing
A team of scientists from the Paul Scherrer Institut, the University of Basel and DESY have demonstrated the first-ever realization of apochromatic X-ray focusing using a tailored combination of a refractive lens and a Fresnel zone plate. This innovative approach enables the correction of the chromatic aberration suffered by both refractive and diffractive lenses over a wide range of X-ray energies. This groundbreaking development in X-ray optics have been just published in the scientific journal Light: Science & Applications.
The evolution of O2 on Ir-based catalysts requires the complete oxidation of their surface to Ir+5
The evolution of O2 occurring in polymer electrolyte water electrolyzer anodes is a very slow reaction that must be catalyzed using iridium (Ir-) based materials. However, Ir is an extremely scarce metal, and thus the extended commercialization of these electrolyzers will only be possible if the amount of Ir implemented in their anodes is drastically reduced. This requires an improved understanding of the individual steps through which these Ir-based materials catalyze the evolution of O2. To shed light on this matter, in this work we studied four different Ir-based catalysts under operative conditions using time resolved X-ray absorption spectroscopy. Our results show for the first time that, despite the differences between these materials, their surfaces must systematically be completely oxidized to a +5 state in order for the evolution of O2 to proceed on them.
Nodeless electron pairing in CsV3Sb5-derived kagome superconductors
The newly discovered kagome superconductors represent a promising platform for investigating the interplay between band topology, electronic order and lattice geometry. Despite extensive research efforts on this system, the nature of the superconducting ground state remains elusive. In particular, consensus on the electron pairing symmetry has not been achieved so far, in part owing to the lack of a momentum-resolved measurement of the superconducting gap structure. Here we report ...
Ultrafast structural changes direct the first molecular events of vision
The visual pigment rhodopsin plays a critical role in the process of low-light vision in vertebrates. It is present in the disk membranes of rod cells in the retina and is responsible for transforming the absorption of light into a physiological signal. Rhodopsin has a unique structure that consists of seven transmembrane (TM) α-helices with an 11-cis retinal chromophore covalently bound to the Lysine sidechain of 7th TM helix. A negatively charged amino acid (glutamate) forms a salt bridge with the protonated Schiff base (PSB) of the chromophore to stabilize the receptor in the resting state.
Rhodopsin transforms the absorption of light into a physiological signal through conformational changes that activate the intracellular G protein transducin—a member of the Gi/o/t family—initiating a signaling cascade, resulting in electrical impulses sent to the brain and ultimately leading to visual perception. Although previous studies have provided valuable insights into the mechanism of signal transduction in rhodopsin, methods that provide both a high spatial and temporal resolution are necessary to fully understand the activation mechanism at the atomic scale from femtoseconds to milliseconds. This study presents the first experimentally-derived picture of the rhodopsin activation mechanism at the atomic scale using time-resolved serial femtosecond crystallography in association with hybrid quantum mechanics/molecular mechanics (QM/MM) simulations. The results show that light-induced structural changes in rhodopsin occur on a timescale of hundreds of femtoseconds, and they reveal new details about the conformational changes that occur during activation.
Quantum disordered ground state in the triangular-lattice magnet NaRuO2
It has long been hoped that spin liquid states might be observed in materials that realize the triangular-lattice Hubbard model. However, weak spin–orbit coupling and other small perturbations often induce conventional spin freezing or magnetic ordering. Sufficiently strong spin–orbit coupling, however, can renormalize the electronic wavefunction and induce anisotropic exchange interactions that promote magnetic frustration.