Iron Oxyhydroxide-Covalent Organic Framework Nanocomposite for Efficient As(III) Removal in Water

The presence of heavy metal ions in water is an environmental issue derived mainly from industrial and mineral contamination. Metal ions such as Cd(II), Pb(II), Hg(II), or As(III) are a significant health concern worldwide because of their high toxicity, mobility, and persistence. Covalent organic frameworks (COFs) are an emerging class of crystalline organic porous materials that exhibit very interesting properties such as chemical stability, tailored design, and low density. COFs also allow the formation of composites with remarkable features because of the synergistic combination effect of their components. These characteristics make them suitable for various applications, among which water remediation is highly relevant. Herein, we present a novel nanocomposite of iron oxyhydroxide@COF (FeOOH@Tz-COF) in which lepidocrocite (γ-FeOOH) nanorods are embedded in between the COF nanoparticles favoring As(III) remediation in water. The results show a remarkable 98.4% As(III) uptake capacity in a few minutes and impressive removal efficiency in a wide pH range (pH 5−11). The chemical stability of the material in the working pH range and the capability of capturing other toxic heavy metals such as Pb(II) and Hg(II) without interference confirm the potential of FeOOH@Tz-COF as an effective adsorbent for water remediation even under harsh conditionsThis work has been supported by the Spanish MINECO (PID2019-106268GB-C32 and PCI2019-103594) and through the “María de Maeztu” Programme for Units of Excellence in R&D (CEX2018-000805-M

Bismuthene - Tetrahedral DNA nanobioconjugate for virus detection

In this work, we present an electrochemical sensor for fast, low-cost, and easy detection of the SARS-CoV-2 spike protein in infected patients. The sensor is based on a selected combination of nanomaterials with a specific purpose. A bioconjugate formed by Few-layer bismuthene nanosheets (FLB) and tetrahedral DNA nanostructures (TDNs) is immobilized on Carbon Screen-Printed Electrodes (CSPE). The TDNs contain on the top vertex an aptamer that specifically binds to the SARS-CoV-2 spike protein, and a thiol group at the three basal vertices to anchor to the FLB. The TDNs are also marked with a redox indicator, Azure A (AA), which allows the direct detection of SARS-CoV-2 spike protein through changes in the current intensity of its electrolysis before and after the biorecognition reaction. The developed sensor can detect SARS-CoV-2 spike protein with a detection limit of 1.74 fg mL 1 directly in nasopharyngeal swab human samples. Therefore, this study offers a new strategy for rapid virus detection since it is versatile enough for different viruses and pathogensPID2020-116728RB-I00, TED2021-129738B–I00, S2018/NMT-4349 TRANSNANOAVANSENS, PDC2021-120782- C21, PID2022-138908NB-C31, PID2021-123295NB-I00, S2018/NMT-4291 TEC2SPAC

Physical Delithiation of Epitaxial LiCoO2 Battery Cathodes as a Platform for Surface Electronic Structure Investigation

We report a novel delithiation process for epitaxial thin films of LiCoO2(001) cathodes using only physical methods, based on ion sputtering and annealing cycles. Preferential Li sputtering followed by annealing produces a surface layer with a Li molar fraction in the range 0.5 < x < 1, characterized by good crystalline quality. This delithiation procedure allows the unambiguous identification of the effects of Li extraction without chemical byproducts and experimental complications caused by electrolyte interaction with the LiCoO2 surface. An analysis by X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) provides a detailed description of the delithiation process and the role of O and Co atoms in charge compensation. We observe the simultaneous formation of Co4+ ions and of holes localized near O atoms upon Li removal, while the surface shows a (2 × 1) reconstruction. The delithiation method described here can be applied to other crystalline battery elements and provide information on their properties that is otherwise difficult to obtainThis work was supported by the Spanish MICINN (grant nos. PID2021-123295NB-I00 and PID2020-117024GB-C43), MAT2017-83722-R, “María de Maeztu” Programme for Units of Excellence in R&D (CEX2018-000805-M), within the framework of UE M-ERA.NET 2018 program under StressLIC Project (grant no. PCI2019-103594) and by the Comunidad Autónoma de Madrid (contract no. PEJD-2019- PRE/IND-15769 and S2108-NMT4321). The authors acknowledge Elettra Sincrotrone Trieste for providing access to its synchrotron radiation facilities. They thank Ignacio Carabias from the Diffraction Unit CAI UCM for his experimental support and helpful comments. The research leading to this result has been supported by the project CALIPSOplus under Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020. M.J., P.M., I.P., and F.B. acknowledge funding from EUROFEL (RoadMap Esfri). The work at the University of Maryland was supported by ONR MURI (Award No. N00014-17-1-2661). The work at Sandia National Laboratories was supported by the Laboratory-Directed Research and Development (LDRD) Program and the DOE Basic Energy Sciences Award number DE-SC0021070. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the US Department of Energy’s National Nuclear Security Administration under contract DE-NA 000352

A multi-technique approach to understanding delithiation damage in LiCoO thin films

We report on the delithiation of LiCoO2 thin films using oxalic acid (C2H2O4) with the goal of understanding the structural degradation of an insertion oxide associated with Li chemical extraction. Using a multi-technique approach that includes synchrotron radiation X-ray diffraction, scanning electron microscopy, micro Raman spectroscopy, photoelectron spectroscopy and conductive atomic force microscopy we reveal the balance between selective Li extraction and structural damage. We identify three different delithiation regimes, related to surface processes, bulk delithiation and damage generation. We find that only a fraction of the grains is affected by the delithiation process, which may create local inhomogeneities. However, the bulk delithiation regime is effective to delithiate the LCO film. All experimental evidence collected indicates that the delithiation process in this regime mimics the behavior of LCO upon electrochemical delithiation. We discard the formation of Co oxalate during the chemical extraction process. In conclusion, the chemical route to Li extraction provides additional opportunities to investigate delithiation while avoiding the complications associated with electrolyte breakdown and simplifying in-situ measurement

Exfoliation of Alpha-Germanium: A Covalent Diamond-Like Structure

2D materials have opened a new field in materials science with outstanding scientific and technological impact. A largely explored route for the preparation of 2D materials is the exfoliation of layered crystals with weak forces between their layers. However, its application to covalent crystals remains elusive. Herein, a further step is taken by introducing the exfoliation of germanium, a narrow-bandgap semiconductor presenting a 3D diamond-like structure with strong covalent bonds. Pure α-germanium is exfoliated following a simple one-step procedure assisted by wet ball-milling, allowing gram-scale fabrication of high-quality layers with large lateral dimensions and nanometer thicknesses. The generated flakes are thoroughly characterized by different techniques, giving evidence that the new 2D material exhibits bandgaps that depend on both the crystallographic direction and the number of layers. Besides potential technological applications, this work is also of interest for the search of 2D materials with new properties

A Guideline to Mitigate Interfacial Degradation Processes in Solid-State Batteries Caused by Cross Diffusion

Diffusion of transition metals across the cathode–electrolyte interface is identified as a key challenge for the practical realization of solid-state batteries. This is related to the formation of highly resistive interphases impeding the charge transport across the materials. Herein, the hypothesis that formation of interphases is associated with the incorporation of Co into the Li7La3Zr2O12 lattice representing the starting point of a cascade of degradation processes is investigated. It is shown that Co incorporates into the garnet structure preferably four-fold coordinated as Co2+ or Co3+ depending on oxygen fugacity. The solubility limit of Co is determined to be around 0.16 per formula unit, whereby concentrations beyond this limit causes a cubic-to-tetragonal phase transition. Moreover, the temperature-dependent Co diffusion coefficient is determined, for example, D700 °C = 9.46 × 10−14 cm2 s−1 and an activation energy Ea = 1.65 eV, suggesting that detrimental cross diffusion will take place at any relevant process condition. Additionally, the optimal protective Al2O3 coating thickness for relevant temperatures is studied, which allows to create a process diagram to mitigate any degradation with a minimum compromise on electrochemical performance. This study provides a tool to optimize processing conditions toward developing high energy density solid-state batteriesD.R. acknowledges financial support by the Austrian Federal Ministry for Digital and Economic Affairs, the National Foundation for Research, Technology, and Development, and the Christian Doppler Research Association (Christian Doppler Laboratory for Solid-State Batteries). D.R. and J.F. acknowledges financial support by the Austrian Science Fund (FWF) in the frame of the project InterBatt (P 31437). D.K. acknowledges funding by the European Union’s Horizon 2020 Research and Innovation Programme (Grant No. 823717, project “ESTEEM3”) and by the Zukunftsfond Steiermark. J.G.S. and D.J.S. acknowledge financial support from the Joint Center for Energy Storage Research (JCESR), an Energy Innovation Hub funded by the U.S. Department of Energy , Office of Science, Basic Energy Sciences. Technical assistance of M. Stypa in crystal growth experiments is greatly acknowledge

Continuous‐Flow Synthesis of High‐Quality Few‐Layer Antimonene Hexagons

2D materials show outstanding properties that can bring many applications in different technological fields. However, their uses are still limited by production methods. In this context, antimonene is recently suggested as a new 2D material to fabricate different (opto)electronic devices, among other potential applications. This work focuses on optimizing the synthetic parameters to produce high-quality antimonene hexagons and their implementation in a large-scale manufacturing procedure. By means of a continuous-flow synthesis, few-layer antimonene hexagons with ultra-large lateral dimensions (up to several microns) and a few nanometers thick are isolated. The suitable chemical post-treatment of these nanolayers with chloroform gives rise to antimonene surfaces showing low oxidation that can be easily contacted with microelectrodes. Therefore, the reported procedure offers a way to solve two critical problems for using antimonene in many applications: large-scale preparation of high-quality antimonene and the ability to set electrical contacts useful for device fabrication.PNICTOCHEM 804110 (G.A.)PID2019-111742-GA-I00CIDEGENT/2018/00

Investigación de la transición aislante-metal en LixCoO2

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física de la Materia Condensada. Fecha de Lectura: 30-10-2023Esta tesis tiene embargado el acceso al texto completo hasta el 30-04-2025An in-depth study of LixCoO2 (LCO) is presented as a platform for understanding the origin of its phenomenology and paving the way for new and improved implementations of this and similar compounds. Li molar fractions (x) were systematically varied to investigate the fundamental origin of the phase transition and the potential implications for future practical applications, such as improved Li-ion batteries, resistive memory devices, or the use of similar compounds with more complex stoichiometries. This study is further motivated by the phase diagram reported for LCO, encompassing structural, insulator-to-metal (IMT), and potentially spin transitions as a function of Li content. We present a novel technique, based on physical methods, for the removal of Li from layered compounds with high mobility ion planes. The delithiation is performed by sputtering-annealing cycles in ultra-high vacuum, maintaining good surface crystallinity. This allowed us to access diferent stoichiometries and thus obtain information about the changes in LCO as a function of x. Additional alkali evaporations (Li and Na) on these compounds were carried our to explore the reversibility of this physical method and obtaining new stoichiometries beyond the conventional range. We shed light on the charge compensation during Li deintercalation in LCO using X-ray photoemission spectroscopy (XPS) and delithiated samples that have not been exposed to chemical or electrochemical processes. The role of the Co atoms and the efects of Co 3d -O 2p hybridization have been analyzed by the simultaneous use of diferent characterization techniques. Throughout this work, we provide a coherent interpretation of several experimental techniques, and our results are discussed in the context of previous research and the fundamental understanding of structural and IMT transitions. A study of the electronic band structure upon hole doping using angle-resolved photoemission spectroscopy (ARPES) has allowed for the three-dimensional mapping of the band dispersion of LCO, facilitating the identifcation of Co 3d t2g energy states involved in the valence band maximum (VBM) and the IMT. This VBM, with a 3-fold dispersion around Γ¯ , is located along the ¯¯ Γ –M symmetry direction. These results were successfully compared with band calculations. Upon Li deintercalation, the renormalization of the valence band is observed, with no additional states forming in the band gap.The evolution of the phase transition in real space using spatially resolved techniques has revealed the coexistence of metallic and insulating phases (Hex-I and Hex-II). We discuss these results in the context of a frst-order phase transition, as is the case for a Mott-type insulator. The observation of phase coexistence in X-ray difraction (XRD) and photoemission microscopy (PEEM), the renormalization of the VB in ARPES, and the predominantly d-d character of the band gap observed in X-ray absorption spectroscopy (XAS) clearly point towards a Mott-Hubbard transition with some O 2p -Co 3d hybridization. Our results are discussed in relation to the family of transition metal oxides (TMOs), reported as having an intermediate character, between Mott-Hubbard and charge transfer insulators. We argue that the efects of delithiation cannot be interpreted in terms of the LixCo1–xO compounds, since structural symmetries, lattice distortions, and charge compensation pathways are not comparable. The efects of sample preparation and surface quality are also addressed to support the use of a physical and non-interacting doping technique for the study of these materials. This work introduces a novel method for exploring the characteristics of insulator-metal transitions in materials. By using LCO as a model system, we have sought to gain a deeper understanding of the fundamental mechanisms that drive this type of phenomenon. The potential application of this approach to other compounds may lay the groundwork for future discoveries and advances in materials science, from rechargeable batteries to novel devices that exploit these propertie

Microwave-assisted synthesis of sulfonic acid-functionalized microporous materials for the catalytic etherification of glycerol with isobutene

Commercial Beta, ZSM-5 and mordenite zeolites and commercial montmorillonite K-10 were successfully sulfonated by a one-step simple method using microwaves. Different amounts of the sulfonating agent were required to maximize the incorporation of sulfonic groups for each structure. This has been related to the different dealumination degree suffered by the starting samples during sulfonation together with the different accessibility of the silanols to the sulfonic groups depending on the arrangement and size of their pores. All optimised sulfonated catalysts showed total conversion and very high selectivity (79–91%) to h-GTBE (glycerol di- and tri-ethers), in spite of their microporosity, due to the incorporation of the sulfonic groups that led to a higher number and strength of Brønsted acid sites. Pore size and arrangement together with the external surface area of the catalysts affected the accessibility of the acid sites to the reactants, explaining the evolution of the catalytic results with time for each structure.Postprint (published version

Microwave-assisted synthesis of sulfonic acid-functionalized microporous materials for the catalytic etherification of glycerol with isobutene

Commercial Beta, ZSM-5 and mordenite zeolites and commercial montmorillonite K-10 were successfully sulfonated by a one-step simple method using microwaves. Different amounts of the sulfonating agent were required to maximize the incorporation of sulfonic groups for each structure. This has been related to the different dealumination degree suffered by the starting samples during sulfonation together with the different accessibility of the silanols to the sulfonic groups depending on the arrangement and size of their pores. All optimised sulfonated catalysts showed total conversion and very high selectivity (79–91%) to h-GTBE (glycerol di- and tri-ethers), in spite of their microporosity, due to the incorporation of the sulfonic groups that led to a higher number and strength of Brønsted acid sites. Pore size and arrangement together with the external surface area of the catalysts affected the accessibility of the acid sites to the reactants, explaining the evolution of the catalytic results with time for each structure