Metallic lithium plays an important role in the development of next-generation lithium metal-based batteries. However, the uncontrolled growth of lithium dendrites limits the use of lithium metal as an anode. In this context, a stable solid electrolyte interphase (SEI) is crucial for regulating dendrite formation, stability, and cyclability of lithium metal anodes.
View Article and Find Full Text PDFThe reversible formation of hydrogen bonds is a ubiquitous mechanism for controlling molecular assembly in biological systems. However, achieving predictable reversibility in artificial two-dimensional (2D) materials remains a significant challenge. Here, we use an external electric field (EEF) at the solid/liquid interface to trigger the switching of H-bond-linked 2D networks using a scanning tunneling microscope.
View Article and Find Full Text PDFCapacity retention is a critical property to enhance in electrochemical storage systems applied to renewable energy. In lithium-sulfur (Li-S) batteries, the capacity fade resulting from the shuttle effect of polysulfides is a major obstacle to their practical application. Sepiolite, an eco-friendly earth-abundant clay with suitable surface chemistry for anchoring and retaining various molecules and structures, was studied as a cathode additive to mitigate the shuttle effect using experimental and theoretical approaches.
View Article and Find Full Text PDFA new direct and straightforward method is proposed to synthesize bare Au nanoparticles (Au NPs) on a quartz surface by nanosecond 532 nm pulsed laser irradiation of a quartz surface in contact with Au(iii) precursor solution. The characterisation by XPS, UV-Vis, SEM and AFM measurements demonstrate the formation of bare Au NPs anchored on the quartz surface with a mean height of 27 ± 10 nm localized in the laser irradiation area. The main features of this approach are their simplicity, quick fabrication and the large surface area covered by Au NPs.
View Article and Find Full Text PDFImmense field enhancement and nanoscale confinement of light are possible within nanoparticle-on-mirror (NPoM) plasmonic resonators, which enable novel optically activated physical and chemical phenomena and render these nanocavities greatly sensitive to minute structural changes, down to the atomic scale. Although a few of these structural parameters, primarily linked to the nanoparticle and the mirror morphology, have been identified, the impact of molecular assembly and organization of the spacer layer between them has often been left uncharacterized. Here, we experimentally investigate how the complex and reconfigurable nature of a thiol-based self-assembled monolayer (SAM) adsorbed on the mirror surface impacts the optical properties of the NPoMs.
View Article and Find Full Text PDFThe electroreduction of CO (CORR) is a promising strategy toward sustainable fuels. Cu is the only Earth-abundant and pure metal capable of catalyzing CO-to-hydrocarbons conversion with significant Faradaic efficiencies; yet, its dynamic structure under CORR conditions remains unknown. Here, we track the Cu structure by electrochemical scanning tunneling microscopy and Raman spectroscopy.
View Article and Find Full Text PDFPhotosynthesis is the model system for energy conversion. It uses CO as a starting reactant to convert solar energy into chemical energy, i.e.
View Article and Find Full Text PDFIn this work, a Mg(0001) single crystal is used as a novel template to grow 2D supramolecular nano-architectures. By using scanning tunnelling microscopy (STM) and high-resolution X-ray photoemission spectroscopy (HR-XPS), the formation of either a homo-molecular or metal-organic network is reported for carboxylic or amino functionalized molecules, respectively.
View Article and Find Full Text PDFChem Commun (Camb)
September 2018
By using high-speed and high-resolution Atomic Force Microscopy (AFM), it was possible to resolve within a single experiment the kinetic pathway in S-layer self-assembly at the solid-liquid interface, obtaining a model that accounts for the nucleation, growth and structural rearrangements in 2D protein self assembly across time (second to hours) and spatial scales (nm to microns).
View Article and Find Full Text PDFThe effect of the Au crystalline plane on the adsorption of different thiols and selenols is studied via reductive desorption (RD) and X-ray photoelectron spectroscopy (XPS) measurements. Self-assembled monolayers (SAMs) using aliphatic (ATs) and aromatic thiols (ArTs) on both Au(111) and Au(100) were prepared. The electrochemical stability of these SAMs on both surfaces is evaluated by comparing the position of the RD peaks.
View Article and Find Full Text PDFThe van der Waals (vdW) interactions of n-alkanethiols (ATs) adsorbed on planar Au(111) and Au(100) surfaces and curved Au nanoparticles of different diameters are reported. By means of electrochemical measurements and molecular dynamic calculations, the increase in the average geometrical curvature of the surface influences the global interactions, that is, decreasing vdW interactions between neighboring molecules. Small NPs do not present the same electrochemical behavior as planar surfaces.
View Article and Find Full Text PDFChem Commun (Camb)
October 2017
A Scanning Tunneling Microscope (STM) is used to induce a reversible transition between different polymorphs in a binary supramolecular network at the liquid/solid interface. The transition is driven externally by switching the polarity of the sample by positive or negative sample bias potentials. We demonstrate that by mixing bias-sensitive and non-sensitive molecules, we gain access to a variety of binary porous structures that can be prepared and reliably actuated for each relative concentration.
View Article and Find Full Text PDFLangmuir
September 2016
The addition of the reducing agent tris(2-carboxyethyl) phosphine (TCEP) during the formation of α,ω-alkanedithiols monolayers on Au(111) using the immersion method produces the assembly of monolayers with bicoordinated molecules (both S-terminal groups bound to the surface) that have a reductive desorption potential that is more positive than for monolayers with monocoordinated molecules in a standing up configuration. We show that the use of TCEP either during formation of the monolayer or as a post treatment procedure allows the controlled formation of monolayers with bicoordinated or monocoordinated configurations. Density functional theory (DFT) calculations were performed to elucidate the role of TCEP in the formation of the bicoordinated configuration.
View Article and Find Full Text PDFThe morphological stability/morphological reshaping of noble metal nanoparticles are studied experimentally in order to unravel the chemical mechanisms lying beneath. Gold and silver nanoparticles (AuNPs and AgNPs, respectively) formed in chloroformic environment are used, as model synthetic systems, to study phenomena of morphological change. The morphological evolution of NPs that follows their formation, is characterized by spectroscopy (UV-Visible, Raman and FTIR) and TEM (Transmission Electron Microscopy).
View Article and Find Full Text PDFWe show that homogeneously mixed self-assembled monolayers (SAMs) of mercaptoalkanoic acids of different chain lengths can be used to build up a pH-sensitive supramolecular switch. The acids with short and long alkyl chains interact via the strong hydrogen bond between carboxylic acid groups. The pH acts as a trigger by breaking or restoring the hydrogen bond interaction in basic or acidic solutions, respectively.
View Article and Find Full Text PDFDynamically switchable supramolecular systems offer exciting possibilities in building smart surfaces, the structure and thus the function of which can be controlled by using external stimuli. Here we demonstrate an elegant approach where the guest binding ability of a supramolecular surface can be controlled by inducing structural transitions in it. A physisorbed self-assembled network of a simple hydrogen bonding building block is used as a switching platform.
View Article and Find Full Text PDFWe use the electric field in a scanning tunneling microscope to manipulate the transition between open and close packed 2D supramolecular networks of neutral molecules in nonpolar media. We found that while the magnitude of the applied field is not decisive, it is the sign of the polarization that needs to be maintained to select one particular polymorph. Moreover, the switching is independent of the solvent used and fully reversible.
View Article and Find Full Text PDFWe investigated the mechanism of formation and stability of self-assembled monolayers (SAMs) of methaneselenolate on Au(111) prepared by the immersion method in ethanolic solutions of dimethyl diselenide (DMDSe). The adsorbed species were characterized by electrochemical measurements and high-resolution photoelectron spectroscopy (HR-XPS). The importance of the headgroup on formation mechanism and the stability of the SAMs was addressed by comparatively studying methaneselenolate (MSe) and methanethiolate (MT) monolayers.
View Article and Find Full Text PDFHigh-resolution photoemission spectroscopy is used to characterize adlayers of ethane-, hexane-, and nonanedithiol molecules grown on Au(111) surfaces by the immersion method. The effect of using a reducing agent during and after the immersion to inhibit or eliminate S-S bonds is investigated. Our results demonstrate that immersion 24 h in millimolar dithiol ethanolic solutions gives rise to the formation of multilayers; this effect is more pronounced in the case of ethanedithiol, the shortest molecule.
View Article and Find Full Text PDFThe preparation and thermal stability of benzenethiol and benzeneselenol self-assembled monolayers (SAMs) grown on Au(111) have been investigated by electrochemical experiments and high-resolution photoemission spectroscopy. Both techniques confirm the formation of monolayers with high packing densities (θ = 0.27-0.
View Article and Find Full Text PDFThe structure, the surface bonding, and the energetics of alkanethiols adsorbed on Cu(111), Ag(111), and Au(111) surfaces were studied under low and high coverages. The potential energy surfaces (PES) for the thiol/metal interaction were investigated in the absence and presence of externally applied electric fields in order to simulate the effect of the electrode potential on the surface bonding. The electric field affects the corrugation of the PES which decreases for negative fields and increases for positive fields.
View Article and Find Full Text PDFContext: The "Standards, Options and Recommendations" (SOR) project, started in 1993, involves a collaboration between the Federation of the French Cancer Centres (FNCLCC), the 20 French Regional Cancer Centres, some French public university and general hospitals and private Clinics and medical scientific societies. Its main objective is the development of clinical practice guidelines to improve the quality of health care and outcome for cancer patients. The methodology is based on a literature review followed by a critical appraisal by a multidisciplinary group of experts to produce the draft guidelines which are then validated by specialists in cancer care delivery.
View Article and Find Full Text PDFContext: The "Standards, Options and Recommendations" (SOR) project, started in 1993, is a collaboration between the Federation of the French Cancer Centres (FNCL CC), the 20 French Cancer Centres and specialists from French Public Universities, General Hospitals and Private Clinics. The main objective is the development of clinical practice guidelines to improve the quality of health care and outcome for cancer patients. The methodology is based on literature review and critical appraisal by a multidisciplinary group of experts, with feed-back from specialists in cancer care delivery.
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