Polyethylene glycol (PEG)-carbon nanotubes (CNTs) with expanded vermiculite (EVM) form-stable composite phase change materials (PCE-CPCMs) were constructed via the efficient synergistic effect between EVM and CNTs. The resultant material demonstrated simultaneously enhanced latent heat and heat transfer. The unique EVM pore structure and CNTs surfaces contributed to the form stability of PCE-CPCMs. The adsorption capacity was 77.75–81.54 wt %. The latent heat of the PCE-CPCMs increased with increasing CNTs content due to the decreasing inhibition effect of EVM and the increasing adsorption capacity of PEG, which was 83.9 J/g during melting and 104.2 J/g during solidification for PCE7.09. The pore confinement and surface EVM interactions inhibited the heat storage capacity of the PCE-CPCMs. Moreover, the inhibition effect on the heat storage capacity of PCE-CPCMs during the melting process was stronger than during solidification due to the crystallization-promoting effect. The heat transfer of PCE-CPCMs was significantly enhanced by the CNTs filler (0.5148 W/(m·K) for PCE7.09) due to the decrease in interfacial thermal resistance and the formation of rapid thermally conductive pathways. Fourier transform infrared spectroscopy, thermogravimetric analysis, and thermal cycles test results confirmed that the PCE-CPCMs exhibited excellent chemical compatibility, thermal stability, and reliability.
Reliable functions of medical implants highly depend on biocompatible, conformal, and stable biointerfaces for seamless biointegration with biological tissues. Though flexible biointerfaces based on synthetic hydrogels have shown promise in optimizing implant biointegration via surgical suturing, physical attachment, or manual preshaping, they still suffer from poor adaptability, such as tissue damage by surgical suturing, low bioactivity, and difficulties in conformal contact and stable fixation, especially for specific tissues of large surface curvatures. Here, we report a bilayer hydrogel-based adaptive biointerface (HAB) made of two polysaccharide derivates, N-hydroxysuccinimide (NHS) ester-activated alginate and chitosan, harnessing dual advantages of their different swelling and active groups. Leveraging on the differential swelling between the two hydrogel layers and covalent linkages with active groups at hydrogel interfaces, HABs can be programmed into sealed tubes with tunable diameters via water-induced compliable shape morphing and instant interfacial adhesion. We further demonstrate that the polysaccharide-based morphing-to-adhesion HAB possesses outstanding bioactivity in directing cellular focal adhesion and intercellular junction, versatile geometrical adaptability to diverse tubular tissues with a wide range of surface curvatures (2.8 × 102–1.3 × 103 m–1), and excellent mechanical stability in high load-/shear-bearing physiological environments (blood flow volume: 85 mm·s–1). HABs overcome the limitations of existing biointerfaces in terms of poor bioactivity and difficult biointegration with biological tissues of large surface curvatures, holding promise to open new avenues for adaptive biointerfaces and reliable medical implants.
Membrane capacitive deionization (MCDI) has emerged as a promising electric-field-driven technology for brackish water desalination and specific salt or charged ion separation. The use of carbon-based or pseudocapacitive materials alone for MCDI usually suffers from the drawbacks of low desalination capacity and poor cycling stability due to their limited accessible adsorption sites and obstructed charge-carrier diffusion pathways. Therefore, developing a hybrid electrode material with multiple charge storage mechanisms and continuous electron/ion transport pathways that can synergistically improve its specific capacitance and cycling durability has currently become one of the most critical technical demands. Herein, we developed a novel hierarchically architectured hybrid electrode by first spinning MXene into polyacrylonitrile (PAN)-based carbon nanofibers (MCNFs) to obtain a highly conductive carbon nanocomposite framework. The excellent spatial support structure can effectively prevent the dense packing of Cl–- and DBS–-doped polypyrrole (PPy) molecular chains during the following electrodeposition process, which not only ensures the efficient transport of electrons in the continuous hybrid carbon nanofibrous skeleton but also provides abundant accessible sites for ion adsorption and insertion. The obtained self-supporting membrane electrodes (MCNF@PPy+Cl– and MCNF@PPy+DBS–) have the advantages of outstanding specific capacitance (318.4 and 153.9 F/g, respectively), low charge transfer resistance (10.0 and 5.3 Ω, respectively), and excellent cycling performance (78% and 90% capacitance retention ratios, respectively, after 250 electrochemical cycles). Furthermore, the asymmetrical membrane electrodes showed a superior desalination capacity of 91.2 mg g–1 in 500 mg/L NaCl aqueous solution and obvious divalent ion (Ca2+, Mg2+) selective adsorption properties in high-salt water from the cooling towers of thermal power plants.
For phase change materials (PCMs) confined in porous structure, the interface interaction between the PCM and the porous skeleton is the key factor to determine the thermal storage performance of PCM. In this study, the modified expanded vermiculite (EVM) was prepared by dopamine modification and DTA + intercalation method and a series of EVM-based composite phase change materials with form shape (fs-CPCMs) were prepared by physical impregnation using n -octadecane as PCMs. The heat storage performance of the composite phase change materials were improved obviously, and the encapsulation ratio is increased to 84.7% and 83.1%. The nonisothermal crystallization process of prepared composite phase change material were further studied. The effects of dopamine modification and organic intercalation on the encapsulation performance of EVM-based fs-CPCMs were analyzed. The results of XRD, FT-IR, thermal cycle, and TGA tests showed that EVM-based composite phase change materials had good chemical compatibility, thermal reliability, and thermal stability. This study provides a theoretical basis for the preparation of EVM-based fs-CPCMs with high thermal stability and good heat storage performance.
Hierarchical macroporous TiO2/graphite-like carbon hybrid photocatalyts were successfully prepared by a facile method employing a particle-stabilized high internal phase emulsion (Pickering emulsion) as the template and sucrose as the carbon source. The results of this study showed that mesopores, with diameters ranging from 10 to 50 nm, were homogeneously distributed on the cell-window structured macropore walls that were armored by nano-sized TiO2 particles. Moreover, a microporous graphitic layer of thickness ∼2 nm surrounded the surface of the TiO2 particles. This type of hierarchical macro-meso-microporous structure with high-efficiency diffusion and mass transfer properties, along with the porous graphitic layers with a high BET surface area, resulted in a hybrid catalyst possessing high adsorption rate and capacity. In addition, the carbon layers suppressed the transition temperature of titania (anatase to rutile) by more than 200 °C. The green method presented here can potentially be employed for the preparation of cost-effective environmental materials toward the degradation of dyes and other pollutants.
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