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Zn metal anode suffers from dendrite issues and passive byproducts, which severely plagues the practical application of aqueous Zn metal batteries. Herein, a polyzwitterionic cross-linked double network hydrogel electrolyte composed of physical crosslinking (hyaluronic acid) and chemical crosslinking (synthetic zwitterionic monomer copolymerized with acrylamide) is introduced to overcome these obstacles. On the one hand, highly hydrophilic physical network provides an energy dissipation channel to buffer stress and builds a H2O-poor interface to avoid side reactions. On the other hand, the charged groups (sulfonic and imidazolyl) in chemical crosslinking structure build anion/cation transport channels to boost ions' kinetics migration and regulate the typical solvent structure [Zn(H2O)6]2+ to R-SO3− [Zn(H2O)4]2+, with uniform electric field distribution and significant resistance to dendrites and parasitic reactions. Based on the above functions, the symmetric zinc cell exhibits superior cycle stability for more than 420 h at a high current density of 5 mA·cm−2, and Zn∥MnO2 full cell has a reversible specific capacity of 150 mAh·g−1 after 1000 cycles at 2 C with this hydrogel electrolyte. Furthermore, the pouch cell delivers impressive flexibility and cyclability for energy-storage applications. [ABSTRACT FROM AUTHOR]

Controlling the orientation of two-dimensional MXene within layered films is essential to optimize or tune their mechanical properties and electromagnetic interference shielding (EMI) performance, but achieving the high orientation MXene layers on an industrial scale remains a challenging goal. In this paper, a scalable layer-by-layer blade coating (LbLBC) method was employed to fabricate highly oriented MXene/polyvinyl alcohol (PVA) films. During the LbLBC process, MXene/PVA colloid suffered a strong shearing effect, which induced the ordered alignment of MXene nanosheets along the direction of the blade movement. The orientation of MXene can be effectively adjusted by changing the scraping gap of LbLBC, achieving a maximum Herman orientation factor f of 0.81. As a result, the mechanical properties and EMI performance of the as-prepared MXene/PVA films are in direct proportion to their orientation, with the optimal values of tensile strength of 145.5 MPa, fracture strain of 19.6%, toughness of 17.7 MJ·m−3, and EMI shielding effectiveness of 36.7 dB. Furthermore, the inherently low mid-infrared (mid-IR) emissivity of MXene, combined with the densely oriented structure affords the composite films with IR stealth, resulting in a substantial decrease from 150 to 66.1 °C in the radiative temperature of a surface. Conclusively, these scalable MXene/PVA films exhibit remarkable potential for integration into the next generation of multifunctional protective camouflage materials. [ABSTRACT FROM AUTHOR]

Highlights: The SiO2 nanofiber membranes and MXene@c-MWCNT6:4 as one unit layer (SMC1) were bonded together with 5 wt% PVA solution. When the structural unit is increased to three layers, the resulting SMC3 has an average electromagnetic interference SET of 55.4 dB and a low thermal conductivity of 0.062 W m−1 K−1. SMCx exhibit stable electromagnetic interference shielding and excellent thermal insulation even in extreme heat and cold environment. A lightweight flexible thermally stable composite is fabricated by combining silica nanofiber membranes (SNM) with MXene@c-MWCNT hybrid film. The flexible SNM with outstanding thermal insulation are prepared from tetraethyl orthosilicate hydrolysis and condensation by electrospinning and high-temperature calcination; the MXene@c-MWCNTx:y films are prepared by vacuum filtration technology. In particular, the SNM and MXene@c-MWCNT6:4 as one unit layer (SMC1) are bonded together with 5 wt% polyvinyl alcohol (PVA) solution, which exhibits low thermal conductivity (0.066 W m−1 K−1) and good electromagnetic interference (EMI) shielding performance (average EMI SET, 37.8 dB). With the increase in functional unit layer, the overall thermal insulation performance of the whole composite film (SMCx) remains stable, and EMI shielding performance is greatly improved, especially for SMC3 with three unit layers, the average EMI SET is as high as 55.4 dB. In addition, the organic combination of rigid SNM and tough MXene@c-MWCNT6:4 makes SMCx exhibit good mechanical tensile strength. Importantly, SMCx exhibit stable EMI shielding and excellent thermal insulation even in extreme heat and cold environment. Therefore, this work provides a novel design idea and important reference value for EMI shielding and thermal insulation components used in extreme environmental protection equipment in the future. [ABSTRACT FROM AUTHOR]

The rational use and conversion of energy are the primary means for achieving the goal of carbon neutrality. MXenes can be used for photothermal conversion, but their opaque appearance limits wider applications. Herein, we successfully develop visible-light transparent and UV-absorbing polymer composite film by solution blending the MXene with polyethylene and then vacuum pressing. The resulting film could be quickly heated to 65 °C under 400 mW cm−2 light irradiation and maintained over 85% visible-light transmittance as well as low haze (<12%). The findings of the indoor heat insulation test demonstrate that the temperature of the glass house model covered by this film was 6-7 °C lower than that of the uncovered model, revealing the potential of transparent film in energy-saving applications. In order to mimic the energy-saving condition of the building in various climates, a typical building model with this film as the outer layer of the window was created using the EnergyPlus building energy consumption software. According to predictions, they could reduce yearly refrigeration energy used by 31-61 MJ m−2, and 3%-12% of the total energy used for refrigeration in such structures. This work imply that the film has wide potential for use as transparent devices in energy-related applications. While MXene-based composites have been reported as promising materials for photothermal conversion, their opaque appearance limits applications. Here, authors demonstrate visible-light transparent and UV-absorbing composite films by vacuum pressing solution blends of MXene with polyethylene. [ABSTRACT FROM AUTHOR]

Efficient and selective extraction of uranium (U(VI)) from seawater is essential for sustainable nuclear power production. This study reports a novel adsorbent zeolitic imidazolate framework (ZIF)-67@SiO2-A/polyacrylamide (PAM) which was synthesized by grafting the core–shell metal–organic frameworks (MOFs)-based nanostructures coated with the 3-aminopropyl triethoxysilane (APTES) functionalized SiO2 (SiO2-A) onto PAM hydrogel. The SiO2 shell was grown on the surface of MOF, which improved the acid-base resistance of MOF. The introduction of ZIF-67@SiO2-A enhances the specific surface area and adsorption efficiency of the PAM. The ZIF-67@SiO2-A/PAM shows remarkable adsorption capacity, fast adsorption kinetics, and good reusability for uranium. It has excellent adsorption property (6.33 mg·g−1, 30 d) in natural seawater. The X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR), energy dispersive spectroscopy (EDS) mappings, and density functional theory reveal that the coordination by N and O in ZIF-67@SiO2-A/PAM with uranium is the main mechanism of uranium adsorption. Thus, ZIF-67@SiO2-A/PAM has great potential to capture uranium from natural seawater. [ABSTRACT FROM AUTHOR]

The use of antibacterial biodegradable polymers is of great importance nowadays in medical applications. In this manuscript, poly(butylenes adipate-co-terephthalate)/poly(lactic acid) blend-based antibacterial bionanocomposites were prepared by melt-processing. We use organically modified montmorillonite (MMT) and graphene nanoplatelets (GNP) as antibacterial property enhancers which are both processing platelike structure, while ciprofloxacin hydrochloride (CFX·HCl) was chosen as a biocide. Either MMT or GNP increases the antibacterial properties during the whole study and tunes the release of CFX·HCl from the bionanocomposites. This was proven by agar diffusion tests and antimicrobial release measurements. The morphology of the bionanocomposites was conducted by using scanning and transmission electron microscopies, and evidence of exfoliation was observed. Contact angle and water uptake of the bionanocomposites were studied showing hydrophilic performance and more percentage water uptake. The final effect on mechanical and blood compatibility was also investigated. The results reveal excellent possibility of using MMT- and GNP-modified PLA/PBAT polymer blends to tune antibacterial properties for specific biomedical applications. [ABSTRACT FROM AUTHOR]