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Decoupling the catalytic and degradation mechanisms of cobalt active sites during acidic water oxidation
No full textAdvancement of iridium free catalysts for the low pH oxygen evolution reaction OER is required to enable multi gigawatt scale proton exchange water electrolysis. Cobalt based materials might address this requirement, but little is known about the mechanism of operation of these OER catalysts at low pH. Here we investigate the nature and evolution of the active cobalt sites along with charge and mass transfer processes that support their catalytic function within a cobalt iron lead oxide material using in situ spectroscopic, gravimetric and electrochemical techniques. We demonstrate that corrosion of the cobalt sites and their reformation through electrooxidation of dissolved Co2 do not affect the catalytic mechanism and are decoupled from the OER. The OER coupled charge transfer is supported by Co 3 amp; 948; oxo species, which are structurally different from those reported for alkaline near neutral conditions and are formed on a relatively slow timescale of minutes. These mechanistic insights might assist in developing genuinely practical catalysts for this vital technolog
Innovation for sustainable accelerating systems The European iSAS Project
Full text linkParticle accelerators are essential instruments for research infrastructures and for a variety of applications, accounting for 40,000 machines worldwide. In a context of sustainability, minimizing the energy consumption of accelerators is an unavoidable challenge. Funded by the EU HORIZON INFRA 2023 TECH 01 01 under GA No. 101131435 , the iSAS project Innovate for Sustainable Accelerating Systems was launched in 2024. It aims to innovate on core technologies of SRF accelerating systems to minimize energy consumption. It will enhance collaborations in the field to broaden and expedite these technologies. It is complementary to other programs developing energy efficient magnets or RF sources and reusing the waste heat produced. The iSAS project concentrates on SRF accelerating systems with the largest leverage for energy savings. The developed technologies aim to optimize ferro electric fast reactive tuners, low lever radio frequency control system, coatings of Nb3Sn on Cu cavities, couplers fundamental, higher order modes and beam line absorbers. iSAS aims to perform R amp;D on these technologies and to promote their implementation towards industry, by raising their TRL level
Production of Nb3Sn film on copper substrate by the bronze route and the RF characterization of samples with the quadrupole resonator
No full textCopper based Nb3Sn cavity is a promising candidate for next generation accelerator applications in the field of superconducting radio frequency SRF . It combines the excellent thermal conductivity of copper and the superior superconducting properties of Nb3Sn, and has the potential to greatly improve the performance of the SRF cavity. The electrochemical and thermal synthesis ETS bronze route is one of the proven methods to achieve Nb3Sn coating on copper. Its advantages are low cost, simple operation, suitable for complex cavity types and mass production. In this report, we have prepared a copper based Nb3Sn sample specifically for Quadrupole Resonator QPR testing. We provide a complete set of QPR sample preparation processes from copper electropolishing, Nb sputtering, electrodeposition and heat treatment to synthesize Nb3Sn. By optimizing the entire preparation process and key parameters, a new Cu based Nb3Sn QPR sample was successfully prepared and its RF properties have been characterized by QPR testing system at HZ
Poly 2 ethyl 2 oxazoline POx as Poly ethylene glycol PEG Lipid Substitute for Lipid Nanoparticle Formulations
Full text linkPolyoxazolines have long been considered as promising alternatives to poly ethylene glycol PEG due to their comparable properties, in particular regarding their stealth effect toward the immune system. Lipid nanoparticles LNPs , as utilized, e.g., in the COVID 19 vaccines, contain PEG lipids. However, alternatives are required because of the PEG dilemma recognized by an increase in anti PEG antibodies in the human population. In this study, poly 2 ethyl 2 oxazoline PEtOx based lipids with different degrees of polymerization are synthesized and subsequently used to formulate mRNA loaded LNPs. The effect of polymer chain length on the size, immunoreaction, and transfection efficiency is investigated in detail. In addition, in depth transfection studies are performed using super resolution microscopy SRM to investigate the uptake mechanism of PEtOx based LNPs in comparison to PEG LNPs. These combined approaches are utilized to identify the best performing LNP, being superior to the commercial PEG lipid used in the Comirnaty formulatio
Triple Evaporation of Bialkali Antimonide Photocathodes and Photoemission Characterization at the PhoTEx Experiment
Full text linkThe development of high performance photocathodes is essential for generating high brightness electron beams required by existing and future accelerators. This work introduces a state of the art triple evaporation growth system designed for bialkali antimonide photocathodes. By enabling the simultaneous deposition of all three materials, this system significantly enhances vacuum stability and the reproducibility of photocathode fabrication. Complementing this, a novel characterization system allows spatially and spectrally resolved measurements of key photocathode parameters, such as quantum efficiency QE , mean transverse energy MTE , reflectance, and lifetime. Crucially, all measurements are performed within a single compact setup, without moving the sample, preserving ultrahigh vacuum conditions. The spectral resolved measurement of the reflectance allows the investigation of the color. Photocathode colorimetry may provide valuable insights into material homogeneity and aging. A Na K Sb photocathode was grown using the triple evaporation method, achieving an initial QE of 5.5 amp; 8201;at 520 amp; 8201;nm. The photocathode was characterized over 2 months, and MTE measurements were performed with two different methods. A dataset with spectral response, reflectance, and colorimetry data was recorded. Together, the triple evaporation growth and the characterization system mark a significant advancement in optimizing photocathodes with exceptional performance, paving the way for brighter and more stable electron sources for next generation accelerator facilitie
Towards a quantitative theory for transmission X ray microscopy
Full text linkTransmission X ray microscopes TXMs are now increasingly used for quantitative analysis of samples, most notably in the spectral analysis of materials. Validating such measurements requires quantitatively accurate models for these microscopes, but current TXM models have only been tested qualitatively. Here we develop an experimental and theoretical framework for evaluation of TXMs that uses Mie theory to compute the electric field emerging from a nanosphere. We approximate the microscope s condenser illumination by plane waves at the mean illumination angle and the zone plate by a thin lens. We find that this model produces good qualitative agreement with our 3D measurements of 60 nm gold nanospheres, but only if both amp; 946; and amp; 948; for the complex refractive index n 1 amp; 948; i amp; 946; of gold are included in the model. This shows that both absorption and phase properties of the specimen influence the acquired TXM image. The qualitative agreement improves if we incorporate a small tilt into the condenser illumination relative to the optical axis, implying a small misalignment in the microscope. Finally, in quantitative comparisons, we show that the model predicts the nanosphere s expected absorption as determined by Beer s law, whereas the microscope underestimates this absorption by 10 20 . This surprising observation highlights the need for future work to identify the microscope feature s that lead to this quantitative discrepanc
In situ Transformation of a Conjugated Nickel Organic Framework into Active Nickel Oxyhydroxide for Electrocatalytic 5 Hydroxymethylfurfural Oxidation
Full text linkUtilizing electrical energy for the targeted conversion of biomass into valuable molecules is a crucial building block for a future circular economy. Herein, a Nickel Ni based conjugated metal organic framework MOF having salicylaldehydate linkages 1, 3, 5 triformylphloroglucinol Tp was synthesized via a solid state process. The resulting 2D framework Ni Tp demonstrates a highly selective electrocatalytic conversion of 5 hydroxymethylfural HMF to 2, 5 furandicarboxylic acid FDCA with excellent faradaic efficiency 96 4 . In situ Raman and X ray absorption spectroscopy XAS reveal that Ni Tp acts as a precatalyst for uniformly dispersed nickel oxy hydroxide NiOOH in the electrocatalytic organic oxidation reaction OOR process. The combination of efficient electron transport of the Ni Tp and the uniform dispersion of newly formed nickel oxy hydroxide with excellent electrolyte availability leads to redox and potentially catalytic activity of all in situ formed nickel sites. Thus, the Ni Tp is an ideal precatalyst in terms of nickel oxy hydroxide active site exposure. This work demonstrates a cost effective method for synthesizing efficient MOF based electrocatalysts for a relevant catalytic reactio
Signature of Topological Surface Bands in Altermagnetic Weyl Semimetal CrSb
No full textAs a special type of collinear antiferromagnetism AFM , altermagnetism has garnered significant research interest recently. Altermagnets exhibit broken parity time symmetry and zero net magnetization, leading to substantial band splitting in the momentum space. Meanwhile, parity time symmetry breaking is a prerequisite for nontrivial band topology in Weyl physics. When there is band crossing, it is usually easy to generate Weyl nodes. Weyl semimetal states have been theoretically proposed in altermagnets; rare reports of experimental observation have been made up to this point. Using angle resolved photoemission spectroscopy ARPES and first principles calculations, we systematically studied the electronic structure of room temperature altermagnet candidate CrSb. We clearly observed the band spin splitting and signature of topological surface states on the 100 cleaved side surface close to the Fermi level originating from bulk band topology. Our results imply that CrSb contains interesting nontrivial topological Weyl physics, in addition to being an excellent room temperature altermagne
Phenothiazine Based Self Assembled Monolayer with Thiophene Head Groups Minimizes Buried Interface Losses in Tin Perovskite Solar Cells
Full text linkSelf assembled monolayers SAMs have revolutionized the fabrication of lead based perovskite solar cells, but they still remain underexplored in tin perovskite systems. To date, PEDOT remains the most effective hole selective layer in tin perovskite solar cells TPSCs , yet it presents challenges for both performance and stability. MeO 2PACz, the only SAM reported for tin perovskites consistently underperforms when compared to PEDOT. In this work, it is identified that MeO 2PACz s limitations stem from excessively strong interactions with the perovskite surface and poor lattice matching, which leads to inferior interface quality. To address these issues, a novel SAM forming molecule called Th 2EPT is designed, synthesized, and characterized. Density functional theory DFT is used to evaluate coordination strength and lattice compatibility, complemented by electro optical characterisation techniques that show significantly reduced interfacial recombination and improve material crystallinity in Th 2EPT Perovskite films. With Th 2EPT, the first SAM based tin perovskite solar cells that outperform PEDOT based devices, delivering a power conversion efficiency PCE of 8.2 with a DMSO free solvent system, are demonstrate
Perovskite CIGSe Tandem Solar Cell Over One Year of Outdoor Monitoring
No full textTandem solar cells can surpass the limitations of single junction devices, promising increased performance due to lower thermalization losses. Even though many research and industrial upscaling efforts are based on perovskite Si tandems, all thin film photovoltaic PV devices, for instance with chalcopyrite CIGSe and perovskite, can offer many advantages such as significant cost and material savings and access to niche markets like building integrated and flexible PV. However, long term stability and outdoor performance of perovskite based tandem devices is to this day challenging. This work presents the first data analysis of year round outdoor measurements mpp tracked of a perovskite chalcopyrite tandem device with a starting efficiency of about 23.14 before encapsulation. The maximum outdoor performance of the tandem device changed during the period of observation, reaching the peak performance in April and then decreased due to the device degradation. At its maximum outdoor performance, the tandem could reach up to 68 higher instantaneous power output, relative to its single junction reference CIGSe SJ . In addition, a quantitative time series performance analysis, exemplary qualitative imaging characterization of the tandem before and after outdoor exposure, is shown. Finally, the possibility of predicting the immediate performance of an all thin film tandem is verified by using a multiple linear regression model with accuracies generally exceeding 9