Separators Modified with Ultrathin Montmorillonite/Polymer Nanocoatings Achieve Dendrite-Free Lithium Deposition at High Current Densities.

Fatal dendritic growth in lithium metal batteries is closely related to the composition and thickness of the modified separator. Herein, an ultrathin nanocoating composed of monolayer montmorillonite (MMT), poly(vinyl alcohol) (PVA) on a polypropylene separator is prepared. The MMT was exfoliated into monolayers (only 0.96 nm) by intercalating PVA under ultrasound, followed by cross-linking with glutaraldehyde. The thickness of the nanocoating on the polypropylene separator, as determined using the pull-up method, is only 200-500 nm with excellent properties. As a result, the lithium-symmetric battery composed of it has a low overpotential (only 40 mV) and a long lifespan of more than 7900 h at high current density, because ion transport is unimpeded and Li+ flows uniformly through the ordered ion channels between the MMT layers. Additionally, the separator exhibited excellent cycling stability in Li-S batteries. This study offers a new idea for fabricating ultrathin clay/polymer modified separators for metal anode stable cycling at high current densities.

Tubular Nanoclay-Enhanced Calcium Phosphate Mineralization and Assembly to Impart High Stiffness and Antimicrobial Properties.

Achieving superior mechanical properties of composite materials in artificially engineered materials is a great challenge due to technical bottlenecks in the size and morphological modulation of inorganic nanominerals. Hence, a "bioprocess-inspired fabrication" is proposed to create multilayered organic-inorganic columnar structures. The sequential assembly of halloysite nanotubes (HNTs), polyelectrolytes (PAAs), and calcium phosphates (CaPs) results in organic-inorganic structures. PAA plays a crucial role in controlling the formation of CaP, guiding it into amorphous particles with smaller nanosizes. The introduction of HNT induces the assembly and maturation of CaP-PAA, leading to the formation of a highly crystalline hydroxyapatite. Poly(vinyl alcohol) was then woven into HNT-encapsulated hydroxyapatite nanorods, resulting in composite materials with basic hierarchical structures across multiple scales. The fabricated composite exhibits exceptional hardness (4.27 ± 0.33 GPa) and flexural strength (101.25 ± 1.72 MPa), surpassing those of most previously developed biological hard tissue materials. Additionally, the composite demonstrates effective antibacterial properties and corrosion resistance, attributed to the dense crystalline phase of CaP. This innovative approach showcases the potential of clay minerals, particularly HNT, in the advancement of biomaterial design. The outstanding mechanical and antimicrobial properties of clay-based composites make them a promising candidate for applications in hard tissue repair, offering versatility in biomedicine and engineering.

Understanding the Nanoscale Affinity between Dissolved Organic Matter and Noncrystalline Mineral with the Implication for Water Treatment.

In recent decades, the concentration of dissolved organic matter (DOM) in aquatic ecosystems has gradually increased, leading to water pollution problems. Understanding the interfacial chemical processes of DOM on natural minerals is important to the exploration of high-efficiency absorbents. However, studying DOM chemical processes and adsorption mechanisms are still challenging due to the complex DOM structure and environmental system. Hence, we characterized the microstructure changes after the formation of amorphous calcium phosphate (ACP) at the interface of montmorillonite (Mt) minerals in a simulated environment system. Combined with atomic force microscopy and density functional theory (DFT) simulation, the mechanism of interfacial interaction between Mt-ACP and DOM was characterized at the molecular level. Moreover, we further evaluated the adsorption behavior of Mt-ACP as a potential adsorbent for organic matter. The comprehensive investigation of humic acid adsorption, intermolecular force, and DFT simulation is conducive to our understanding of the interfacial interaction mechanism between organic matter and noncrystalline minerals in aquatic environments and provides new perspectives on the application of clay-based mineral materials in pollutant removal under exposure from DOM.

Functionalized Halloysite Scaffold Controls Sodium Dendrite Growth.

Sodium metal is one of the most promising anodes for the prospective low-cost rechargeable batteries. Nevertheless, the commercialization of Na metal anodes remains restricted by sodium dendrite growth. Herein, halloysite nanotubes (HNTs) were chosen as the insulated scaffolds, and Ag nanoparticles were introduced as sodiophilic sites to achieve uniform sodium deposition from bottom to top under the synergistic effect. Density functional theory (DFT) calculation results demonstrated that the presence of Ag greatly increased the binding energy of sodium on HNTs/Ag (-2.85 eV) vs HNTs (-0.85 eV). Meanwhile, thanks to the opposite charges on the inner and outer surfaces of HNTs, faster Na+ transfer kinetics and selective adsorption of SO3CF3- on the inner surface of HNTs were achieved, thus avoiding the formation of space charge. Accordingly, the coordination between HNTs and Ag afforded a high Coulombic efficiency (about 99.6% at 2 mA cm-2), long lifespan in a symmetric battery (for over 3500 h at 1 mA cm-2), and remarkable cycle stability in Na metal full batteries. This work offers a novel strategy to design a sodiophilic scaffold by nanoclay for dendrite-free Na metal anodes.

Nanoscale Interactions of Humic Acid and Minerals Reveal Mechanisms of Carbon Protection in Soil.

The concentrations of terrestrially sourced dissolved organic matter (DOM) have expanded throughout aquatic ecosystems in recent decades. Although sorption to minerals in soils is one major pathway to sequestrate soil organic matter, the mechanisms of organic matter-mineral interactions are not thoroughly understood. Here, we investigated the effect of calcium phosphate mineralization on humic acid (HA) fixation in simulated soil solutions, either with or without clay mineral montmorillonite (Mt). We found that Mt in solution promoted nucleation and crystallization of calcium phosphate (CaP) due to amorphous calcium phosphate clustering and coalescence on Mt surface, which contributed to the long-term persistence and accumulation of HA. Organic ligands with specific chemical groups on HA have higher binding energies to CaP-Mt than to CaP/Mt, according to dynamic force spectroscopy observations. Moreover, CaP-Mt formed in solution showed a great capacity for HA adsorption with a maximum adsorption quantity of 156.89 mg/g. Our findings directly support that Mt is crucial for DOM sequestration by facilitating CaP precipitation/transformation. This has an impact on how effectively we understand the long-term turnover of DOM and highlights knowledge gaps that might assist in resolving essential soil C sequestration issues.

Ethanol extract of Polygonum cuspidatum inhibits hepatitis B virus in a stable HBV-producing cell line.

Chronic hepatitis B virus (HBV) infection is endemic in Asia and its consequences are among the major public health problems in the world. Unfortunately, the therapeutic efficacies of present strategies are still unsatisfactory with a major concern about viral mutation. In search of effective antiviral agent, we examined the efficacy of extracts of Polygonum cuspidatum Sieb. et Zucc. (P. cuspidatum) against HBV in HepG2 2.2.15 cells by quantitative real time polymerase chain reaction. The expressions of viral antigens, HBeAg and HBsAg, were also determined by enzyme linked immunosorbent assay. The ethanol extract of P. cuspidatum could inhibit dose-dependently the production of HBV (p<0.0001) with an effective minimal dosage of 10 microg/ml. The water extract of P. cuspidatum might also inhibit the production of HBV at a higher dosage. The expression of HBsAg was significantly increased by both ethanol extract and water extract of P. cuspidatum dose-dependently (p<0.0001) and time-dependently (p<0.0001). Higher dose of water extract of P. cuspidatum (30 microg/ml) could inhibit the expression of HBeAg (p<0.05). The extract of P. cuspidatum might contain compounds that would contribute to the control of HBV infection in the future. However, its promoting effect on the expression of HBsAg and its cytotoxicity should be monitored. Further purification of the active compounds, identification and modification of their structures to improve the efficacy and decrease the cytotoxicity are required.