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Interfacial assembly of two-dimensional MXenes

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Journal of Energy Chemistry 2021年第9期30卷 417-434页

作者： Chuanfang(John)Zhang Laboratory for Functional Polymers Swiss Federal Laboratories for Materials Science and Technology(Empa)ETH DomainUberlandstrasse 129CH-8600 DubendorfSwitzerland

Two-dimensional(2D) transition metal carbides, carbonitrides and nitrides, known as MXenes, are emerging quickly at the frontiers of 2D materials world. Their exotic properties such as the highest electrical conductivity among all solution-processed 2 D materials, the best electromagnetic interference shielding performance outperforming that of copper or aluminum at a nanoscale thickness, as well as the highest volumetric capacitance for pseudocapacitors, have been attracting extensive fundamental research and applications. Their unique surface chemistries, that is, hydrophilic groups terminated on the surface of MXenes after etching and delamination, enable plenty of opportunities for assembling into MXene building blocks. Particularly, assembling at liquid–liquid, liquid–solid, liquid–air, and solid–solid interfaces allows the efficient fabrication of various structures, including MXene surfactants, MXene heterostructures, MXene transparent films. Interfacial assembly of MXenes is of significance in unveiling more versatilities of MXenes as well as impacts on novel MXene-based architectures, based on which enhanced performance of devices is achieved. As such, this review focuses on the interfacial assembly of MXenes, explaining mechanisms behind various assembling and providing classical examples for corresponding interfacial assembling techniques. Applications of these as-assembled architectures are also discussed in brief. We believe this review may shed light on the interfacial chemistry of MXenes, thus guiding more efficient fabrication of MXene-based functional films/coatings/electrodes/devices.

关键词： Interfacial assembly MXene Interfacial tension Crosslinking Heterostructures

Low Na-β″-alumina electrolyte/cathode interfacial resistance enabled by a hydroborate electrolyte opening up new cell architecture designs for all-solid-state sodium batteries

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Materials Futures 2022年第3期1卷 1-8页

作者： Marie-Claude Bay Rabeb Grissa Konstantin V Egorov Ryo Asakura Corsin Battaglia empa Swiss Federal Laboratories for Materials Science and TechnologyÜberlandstrasse 1298600 DübendorfSwitzerland

Development of low-resistance electrode/electrolyte interfaces is key for enabling all-solid-state batteries with fast-charging *** interfacial resistance and high current density were demonstrated for Na-β″-alumina/sodium metal interfaces,making Na-β″-alumina a promising solid electrolyte for high-energy all-solid-state ***,integration of Na-β″-alumina with a high-energy sodium-ion intercalation cathode remains ***,we report a proof-of-concept study that targets the implementation of a Na-β″-alumina ceramic electrolyte with a slurry-casted porous NaCrO_(2) cathode with infiltrated sodium hydroborates as secondary *** hydroborate Na4(B_(12)H_(12))(B_(10)H_(10))possesses similar sodium-ion conductivity of 1 mS cm^(-1) at room temperature as Na-β″-alumina and can be fully densified by cold *** the Na4(B_(12)H_(12))(B_(10)H_(10))secondary electrolyte as interlayer between Na-β″-alumina and NaCrO_(2),we obtain a cathode-electrolyte interfacial resistance of only 25Ωcm^(2) after cold pressing at 70 ***-of-concept cells with a sodium metal anode and a NaCrO_(2) cathode feature an initial discharge capacity of 103 mAh g^(-1) at C/10 and 42 mAh g^(-1) at 1 C with an excellent capacity retention of 88%after 100 cycles at 1 C at room ***-milled cross-sections of the cathode/electrolyte interface demonstrate that intimate contact is maintained during cycling,proving that the use of hydroborates as secondary electrolyte and as an interlayer is a promising approach for the development of all-solid-state batteries with ceramic electrolytes.

关键词： interface all-solid-state battery sodium metal anode hydroborate electrolyte Na-β″-alumina electrolyte

Sub-stoichiometric functionally graded titania fibres for water-splitting applications

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Journal of Semiconductors 2015年第6期36卷 11-16页

作者： Vaia Adamaki A.Sergejevs C.Clarke F.Clemens F.Marken C.R.Bowen Mechanical Engineering Department University of Bath Electronic and Electrical Engineering Department University of Bath High Performance Ceramics EMPA Materials Science and Technology Chemistry Department University of Bath

The photo-electro-chemical （PEC） splitting of water requires semiconductor materials with a minimum energy gap of 1.23 eV along with conduction and valence bands overlapping the oxidation of H20 and reduction of H＋ respectively. This work overcomes the limitations of stoichiometric titania by manufacturing fine scale fibres that exhibit a compositional gradient of oxygen vacancies across the fibre length. In such a fibre configuration the fibre end that is chemically reduced to a relatively small extent performs as the photoanode and the oxygen vacan- cies enhance the absorption of light. The fibre end that is reduced the most consists of Magn61i phases and exhibits metallic electrical conductivity that enhances the electron-hole separation. The structure and composition of the functionally graded fibres, which were manufactured through extrusion, pressureless sintering and carbo-thermal reduction, are studied using XRD and electron microscopy. Electrochemical impedance spectroscopy measure- ments were performed in a three-electrode electrochemical system and showed that the oxygen vacancies in the functionally graded fibres affect the fiat band potential and have increased carrier density. The efficiency of the system was evaluated with PEC measurements that shows higher efficiency for the functionally graded fibres com- pared to homogeneous TiO2 or Magn61i phase fibres. The functionally graded and fine scale fibres have the potential to be used as an array of active fibres for water splitting applications.

关键词： titania suboxides water splitting photocurrent

Atmospheric dispersion of chemical,biological,and radiological hazardous pollutants:Informing risk assessment for public safety

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Journal of Safety Science and Resilience 2022年第4期3卷 372-397页

作者： Xiaole Zhang Jing Wang Institute of Environmental Engineering(IfU) ETH ZürichZürichCH 8093Switzerland Laboratory for Advanced Analytical Technologies EmpaDübendorfCH 8600Switzerland

Modern society is confronted with emerging threats from chemical,biological,and radiological(CBR)hazardous substances,which are intensively utilized in the chemical,medical,and energy *** atmospheric dis-persion of released CBR hazardous pollutants can influence a large percentage of the population owing to their rapid process with extensive spatial *** is important to comprehensively understand the behaviors of the released CBR pollutants in the atmosphere to fully evaluate the risks and protect public *** this study,we reviewed the advancements in the atmospheric transport of CBR pollutants,including the urban atmospheric boundary layer,unique concepts,and models for CBR *** underlined the development of innovative methodologies(e.g.,inverse estimation and data assimilation methods)for the atmospheric transport of acciden-tally released CBR pollutants to reduce uncertainties in emissions and accumulated errors during dispersion by combining numerical models with monitoring ***,we introduced progress in quantitative risk assess-ment,including exposure assessment and dose-response relationships for CBR hazardous pollutants.A framework,source,assimilation,fundamentals,exposure,and risk(SAFER),has been proposed to integrate the key compo-nents in the risk assessment of airborne CBR hazardous *** methods and models can contribute to effective risk preparedness,prevention,evidence-based policymaking,and emergency response to airborne CBR pollutants.

关键词： Atmospheric dispersion Bioaerosols Toxic and flammable chemicals Radiation Nuclear accident Industrial accident Data assimilation Dose-response relations Exposure Quantitative risk assessment Probabilistic risk assessment

New approach for time-resolved and dynamic investigations on nanoparticles agglomeration

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Nano Research 2020年第10期13卷 2847-2856页

作者： Neda Iranpour Anaraki Amin Sadeghpour Kamran Iranshahi Claudio Toncelli Urszula Cendrowska Francesco Stellacci Alex Dommann Peter Wick Antonia Neels Center for X-ray Analytics EmpaSwiss Federal Laboratories for Materials Science and Technology St.Gallen 9014Switzerland Laboratory of Particles Biology Interactions EmpaSwiss Federal Laboratories for Materials Science and TechnologySt.Gallen 9014Switzerland Department of Chemistry University of FribourgChemin du MuseeFribourg 1700Switzerland Laboratory for Biomimetic Membranes and Textiles EmpaSwiss Federal Laboratories for Materials Science and TechnologySt.Gallen 9014Switzerland Department of Environmental Systems Science Swiss FPederal Institute of TechnologyETH-ZurichZurich 8092Switzerland Institute of Materials EPFLLausanne 1015Switzerland Cellular and Biomedical Sciences Faculty of MedicineUniversity of BernBern 3012Swizerland

Nanoparticle (NP) colloidal stability plays a crucial role in biomedical application not only for human and environmental safety but also for NP efficiency and functionality. NP agglomeration is considered as a possible process in monodispersed NP colloidal solutions, which drastically affects colloidal stability. This process is triggered by changes in the physicochemical properties of the surrounding media, such as ionic strength (IS), pH value, or presence of biomolecules. Despite different available characterization methods for nanoparticles (NPs), there is a lack of information about the underlying mechanisms at the early stage of dynamic behaviors, namely changing in NP size distribution and structure while placing them from a stable colloidal solution to a new media like biological fluids. In this study, an advanced in situ approach is presented that combines small angle X-ray scattering (SAXS) and microfluidics, allowing label-free, direct, time-resolved, and dynamic observations of the early stage of NP interaction/agglomeration initiated by environmental changes. It is shown for silica NPs that the presence of protein in the media enormously accelerates the NP agglomeration process compared to respective changes in IS and pH. High IS results in a staring agglomeration process after 40 min, though, in case of protein presence in media, this time decreased enormously to 48 s. These time scales show that this method is sensitive and precise in depicting the dynamics of fast and slow NP interactions in colloidal conditions and therefore supports understanding the colloidal stability of NPs in various media concluding in safe and efficient NP designing for various applications.

关键词： microfluidic small-angle X-ray scattering(SAXS) in situ dynamic measurements nanoparticle agglomeration biological environment label-free

Integrative filtration research and sustainable nanotechnology

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Particuology 2013年第1期11卷 5-13页

作者： Jing Wang Drew Thompson David Y.H.Pui Institute of Environmental Engineering ETH Zurich 8093Switzerland Analytical Chemistry Empa8600 DubendorfSwitzerland Particle Technology Laboratory University of Minnesota55455USA

With the wide applications of nanomaterials in an array of industries, more concerns are being raised about the occupational health and safety of nanoparticles in the workplace, and implications ofnanotech- nology on the environment and living systems. Studies on environmental, health and safety （EHS） issues of nanomaterials play a significant role in public acceptance, and eventual sustainability, of nanotechnol- ogy. We present research results on three aspects of the EHS studies： characterization and measurement of nanoparticles, nanoparticle emission and exposure at workplaces, and control and abatement of nanoparticle release using filtration technology. Measurement of nanoparticle agglomerates using a newly developed instrument, the Universal Nanoparticle Analyzer, is discussed. Nanoparticle emission and exposure measurement results for carbon nanotubes in the manufacture of nanocomposites and for silicon nanoparticles in their production at a pilot scale facility are presented. Filtration of nanoparticles and nanoparticle agglomerates are also studied.

关键词： Agglomerate Sustainability Exposure Filtration Nano-EHS Nanoparticle

Longs short-term based semi-supervised memory encoder-decoder for early prediction of failures in self-lubricating bearings

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Friction 2023年第1期11卷 109-124页

作者： Vigneashwara PANDIYAN Mehdi AKEDDAR Josef PROST Georg VORLAUFER Markus VARGA Kilian WASMER Laboratory for Advanced Materials Processing(LAMP) Swiss Federal Laboratories for Materials Science and Technology(Empa)Thun CH-3602Switzerland AC2T research GmbH Wiener Neustadt 2700Austria

The existing knowledge regarding the interfacial forces,lubrication,and wear of bearings in real-world operation has significantly improved their designs over time,allowing for prolonged service *** a result,self-lubricating bearings have become a viable alternative to traditional bearing designs in industrial ***,wear mechanisms are still inevitable and occur progressively in self-lubricating bearings,as characterized by the loss of the lubrication film and ***,monitoring the stages of the wear states in these components will help to impart the necessary countermeasures to reduce the machine maintenance *** article proposes a methodology for using a long short-term memory(LSTM)-based encoder-decoder architecture on interfacial force signatures to detect abnormal regimes,aiming to provide early predictions of failure in self-lubricating sliding contacts even before they *** sliding experiments were performed using a self-lubricating bronze bushing and steel shaft journal in a custom-built transversally oscillating tribometer *** force signatures corresponding to each cycle of the reciprocating sliding motion in the normal regime were used as inputs to train the encoder-decoder architecture,so as to reconstruct any new signal of the normal regime with the minimum *** this semi-supervised training exercise,the force signatures corresponding to the abnormal regime could be differentiated from the normal regime,as their reconstruction errors would be very *** the validation procedure for the proposed LSTM-based encoder-decoder model,the model predicted the force signals corresponding to the normal and abnormal regimes with an accuracy of 97%.In addition,a visualization of the reconstruction error across the entire force signature showed noticeable patterns in the reconstruction error when temporally decoded before the actual critical failure point,making it possible to be used for early predic

关键词： predictive maintenance in-situ sensing long short-term memory(LSTM) encoder-decoder wear monitoring tribology

Unraveling and optimizing the metal-metal oxide synergistic effect in a highly active Co_(x)(CoO)_(1–x) catalyst for CO_(2) hydrogenation

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Journal of Energy Chemistry 2021年第2期30卷 241-250,I0009页

作者： Kun Zhao Marco Calizzi Emanuele Moioli Mo Li Alexandre Borsay Loris Lombardo Robin Mutschler Wen Luo Andreas Zuttel Laboratory of Materials for Renewable Energy Institute of Chemical Sciences and Engineeringtcole Polytechnique Federale de Lausanne(EPFL)1951 SionSwitzerland Swiss Federal Laboratories for Materials Science and Technology(empa) 8600 DiibendorfSwitzerland

The relation between catalytic reactivities and metal/metal oxide ratios, as well as the functions of the metal and the metal oxides were investigated in the CO_2 hydrogenation reaction over highly active Co_x(CoO)_(1–x)catalysts in operando. The catalytic reactivity of the samples in the CO_2 methanation improves with the increased Co O concentration. Strikingly, the sample with the highest concentration of CoO, i.e., Co_(0.2)(CoO)_(0.8), shows activity at temperatures lower than 200 °C where the other samples with less CoO are inactive. The origins of this improvement are the increased amount and moderate binding of adsorbed CO_2 on CoO sites. The derivative adsorption species are found to be intermediates of the CH4 formation. The metallic Co functions as the electronically catalytic site which provides electrons for the hydrogenation steps. As a result, an abundant amount of CoO combined with Co is the optimal composition of the catalyst for achieving the highest reactivity for CO_2 hydrogenation.

关键词： Cobalt and cobalt oxide Reactivity CO_(2)hydrogenation Active site Adsorption Activation energy

Functional Fiber Membranes with Antibacterial Properties for Face Masks

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Advanced Fiber Materials 2023年第4期5卷 1519-1533页

作者： Papada Natsathaporn Gordon Herwig Stefanie Altenried Qun Ren René M.Rossi Daniel Crespy Fabian Itel Department of Materials Science and Engineering School of Molecular Science and EngineeringVidyasirimedhi Institute of Science and Technology(VISTEC)Rayong 21210Thailand Laboratory for Biomimetic Membranes and Textiles EmpaSwiss Federal Laboratories for Materials Science and TechnologyLerchenfeldstrasse 59014 St.GallenSwitzerland Laboratory for Biointerfaces EmpaSwiss Federal Laboratories for Materials Science and TechnologyLerchenfeldstrasse 59014 St.GallenSwitzerland

Reusable face masks are an important alternative for minimizing costs of disposable and surgical face masks during *** complementary to washing,a prolonged lifetime of face masks relies on the incorporation of self-cleaning *** development of self-cleaning face mask materials requires the presence of a durable catalyst to deactivate contaminants and microbes after long-term use without reducing filtration ***,we generate self-cleaning fibers by functionalizing silicone-based(polydimethylsiloxane,PDMS)fibrous membranes with a *** electro-spinning is performed to fabricate fibers with a non-crosslinked silicone core within a supporting shell scaffold,followed by thermal crosslinking and removal of the water-soluble *** zinc oxide nanoparticles(ZnO NPs)are immo-bilized on the PDMS fibers by colloid-electrospinning or post-functionalization *** fibers functionalized with ZnO NPs can degrade a photo-sensitive dye and display antibacterial properties against Gram-positive and Gram-negative bacteria(Escherichia coli and Staphylococcus aureus)due to the generation of reactive oxygen species upon irradiation with UV ***,a single layer of functionalized fibrous membrane shows an air permeability in the range of 80-180 L/m^(2)s and 65%filtration efficiency against fine particulate matter with a diameter less than 1.0µm(PM_(1.0)).

关键词： Polydimethylsiloxane Zinc oxide Face mask Electrospinning Antibacterial