Copper (Cu) nanoparticles (NPs) have received extensive interest owing to their advantageous properties compared with their bulk counterparts. Although the natural oxidation of Cu NPs can be alleviated by passivating the surfaces with additional moieties, obtaining non-oxidized bare Cu NPs in air remains challenging. Here we report that bare Cu NPs with surface excess electrons retain their non-oxidized state over several months in ambient air. Cu NPs grown on an electride support with excellent electron transfer ability are encapsulated by the surface-accumulated excess electrons, exhibiting an ultralow work function of ~3.2 eV. Atomic-scale structural and chemical analyses confirm the absence of Cu oxide moiety at the outermost surface of air-exposed bare Cu NPs. Theoretical energetics clarify that the surface-accumulated excess electrons suppress the oxygen adsorption and consequently prohibit the infiltration of oxygen into the Cu lattice, provoking the endothermic reaction for oxidation process. Our results will further stimulate the practical use of metal NPs in versatile applications.
Multiscale and multimodal imaging of material structures and properties provides solid ground on which materials theory and design can flourish. Recently, KAIST announced 10 flagship research fields, which include KAIST Materials Revolution: Materials and Molecular Modeling, Imaging, Informatics and Integration (M3I3). The M3I3 initiative aims to reduce the time for the discovery, design and development of materials based on elucidating multiscale processing–structure–property relationship and materials hierarchy, which are to be quantified and understood through a combination of machine learning and scientific insights. In this review, we begin by introducing recent progress on related initiatives around the globe, such as the Materials Genome Initiative (U.S.), Materials Informatics (U.S.), the Materials Project (U.S.), the Open Quantum Materials Database (U.S.), Materials Research by Information Integration Initiative (Japan), Novel Materials Discovery (E.U.), the NOMAD repository (E.U.), Materials Scientific Data Sharing Network (China), Vom Materials Zur Innovation (Germany), and Creative Materials Discovery (Korea), and discuss the role of multiscale materials and molecular imaging combined with machine learning in realizing the vision of M3I3. Specifically, microscopies using photons, electrons, and physical probes will be revisited with a focus on the multiscale structural hierarchy, as well as structure–property relationships. Additionally, data mining from the literature combined with machine learning will be shown to be more efficient in finding the future direction of materials structures with improved properties than the classical approach. Examples of materials for applications in energy and information will be reviewed and discussed. A case study on the development of a Ni–Co–Mn cathode materials illustrates M3I3’s approach to creating libraries of multiscale structure–property–processing relationships. We end with a future outlook toward recent developments in the field of M3I3.
This review reports progress in solid electrolytes integrated into all-solid-state 2D and 3D lithium-ion microbatteries. The latest improvements, performance and challenges of the all-solid-state 2D and 3D structured microbatteries are analyzed.
The present study examines various methods used for the characterization of three common natural silicate minerals, one zeolite (clinoptilolite) and two clays (montmorillonite and vermiculite). Characterization of natural minerals were performed through a series of analytical measurements so as gather all the information needed regarding their properties, in order to distinguish them from "similar" minerals such in the case of clinoptilolite vs heulandite and vermiculite vs hydrobiotite; this will enable their further use in environmental applications. The methods used in the present study are XRD, XRF, FTIR spectroscopy, TG/DTG/DTA and N2-porosimetry (BET). Data revealed from XRD, FTIR, TG/DTG/DTA showed that all three minerals have characteristic bands that can characterized and distinguish each other. The key difference between Heulandite and Clinoptilolite is their behavior upon heating. Clinoptilolite is stable at temperatures exceeding 450 o C, where heulandites undergo structural collapse below 450 o C. XRF analysis showed that Vermiculite sample is rich in MgO (Mg-vermiculite) and the low concentration of K2O revealed the presence of Vermiculite instead of Hydrobiotite. Thermogravimetric analysis showed that the main regions of Clinoptilolite weight loss are the release of looselybound water (50-200°C), release of "zeolitic" water (200-700°C) and finally the collapse of crystal structure (700-900°C). In the range 25-400 o C, the endothermal (DTA diagram) process of dehydration occurred in one step. This reveals the presence of clinoptilolite, because for heulandites dehydration occurs in two steps. As far as porosity is concerned, all three minerals are generally dominated by micro/mesopores. BET surface area for clinoptilolite is between 17-100 m2/g, for bentonite 22-42 m 2 /g and for vermiculite 7-18 m 2 /g. The acquired analytical results enabled the full characterization of the examined minerals, despite their common properties.
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