Redox Flow Capacitive Deionization in a Mixed Electrode Solvent of Water and Ethanol

In the redox flow electrode capacitive deionization (FCDI), the solubility of redox electrolyte and flowability of carbon slurry have great influence on the salt removal rate and energy consumption. In this work, a mixed solvent electrolyte is proposed in FCDI, which consists of iodide/triiodide redox couples and carbon slurry in the mixed solvent of water and ethanol (1:1). At the current density of 5 mA cm-2, the salt removal rate can reach up to 2.72 μg cm-2 s-1 in a mixed solvent, which is much higher than 1.74 μg cm-2 s-1 in aqueous solution and 2.37 μg cm-2 s-1 in the ethanol solution. This may be owing to the fast transport of ions during redox reaction in organic solvent and the excellent flowability of carbon slurry in the aqueous condition, which can provide more reaction sites for iodide/triiodide redox reaction and faster electron transportation. This unique FCDI with organic and aqueous mixed solvent electrolyte will provide a new perspective for the development of redox flow electrochemical desalination.

Recapitulation of selective nuclear import and export with a perfectly repeated 12mer GLFG peptide

The permeability barrier of nuclear pore complexes (NPCs) controls nucleocytoplasmic transport. It retains inert macromolecules while allowing facilitated passage of importins and exportins, which in turn shuttle cargo into or out of cell nuclei. The barrier can be described as a condensed phase assembled from cohesive FG repeat domains. NPCs contain several distinct FG domains, each comprising variable repeats. Nevertheless, we now found that sequence heterogeneity is no fundamental requirement for barrier function. Instead, we succeeded in engineering a perfectly repeated 12mer GLFG peptide that self-assembles into a barrier of exquisite transport selectivity and fast transport kinetics. This barrier recapitulates RanGTPase-controlled importin- and exportin-mediated cargo transport and thus represents an ultimately simplified experimental model system. An alternative proline-free sequence forms an amyloid FG phase. Finally, we discovered that FG phases stain bright with ‘DNA-specific’ DAPI/ Hoechst probes, and that such dyes allow for a photo-induced block of nuclear transport.

Assembly of Copolymer and Metal−Organic Framework HKUST-1 to Form Cu2−xS/CNFs Intertwining Network for Efficient Electrocatalytic Hydrogen Evolution

The construction of complex intertwined networks that provide fast transport pathways for ions/electrons is very important for electrochemical systems such as water splitting, but a challenge. Herein, a three dimensional (3-D) intertwined network of Cu2−xS/CNFs (x = 0 or 0.04) has been synthesized through the morphology-preserved thermal transformation of the intertwined PEG-b-P4VP/ HKUST-1 hybrid networks. The strong interaction between PEG chains and Cu2+ is the key to the successful assembly of PEG-b-P4VP nanofibers and HKUST-1, which inhibits the HKUST-1 to form individual crystalline particles. The obtained Cu2−xS/CNFs composites possess several merits, such as highly exposed active sites, high-speed electronic transmission pathways, open pore structure, etc. Therefore, the 3-D intertwined hierarchical network of Cu2−xS/CNFs displays an excellent electrocatalytic activity for HER, with a low overpotential (η) of 276 mV to reach current densities of 10 mA cm−2, and a smaller Tafel slope of 59 mV dec−1 in alkaline solution.

Optical-Cavity-Induced Current

The formation of a submicron optical cavity on one side of a metal–insulator–metal (MIM) tunneling device induces a measurable electrical current between the two metal layers with no applied voltage. Reducing the cavity thickness increases the measured current. Eight types of tests were carried out to determine whether the output could be due to experimental artifacts. All gave negative results, supporting the conclusion that the observed electrical output is genuinely produced by the device. We interpret the results as being due to the suppression of vacuum optical modes by the optical cavity on one side of the MIM device, which upsets a balance in the injection of electrons excited by zero-point fluctuations. This interpretation is in accord with observed changes in the electrical output as other device parameters are varied. A feature of the MIM devices is their femtosecond-fast transport and scattering times for hot charge carriers. The fast capture in these devices is consistent with a model in which an energy ∆E may be accessed from zero-point fluctuations for a time ∆t, following a ∆E∆t uncertainty-principle-like relation governing the process.

“Artificial Wood” Lignocellulosic Membranes: Influence of Kraft Lignin on the Properties and Gas Transport in Tunicate-Based Nanocellulose Composites

Nanocellulose membranes based on tunicate-derived cellulose nanofibers, starch, and ~5% wood-derived lignin were investigated using three different types of lignin. The addition of lignin into cellulose membranes increased the specific surface area (from 5 to ~50 m2/g), however the fine porous geometry of the nanocellulose with characteristic pores below 10 nm in diameter remained similar for all membranes. The permeation of H2, CO2, N2, and O2 through the membranes was investigated and a characteristic Knudsen diffusion through the membranes was observed at a rate proportional to the inverse of their molecular sizes. Permeability values, however, varied significantly between samples containing different lignins, ranging from several to thousands of barrers (10−10 cm3 (STP) cm cm−2 s−1 cmHg−1cm), and were related to the observed morphology and lignin distribution inside the membranes. Additionally, the addition of ~5% lignin resulted in a significant increase in tensile strength from 3 GPa to ~6–7 GPa, but did not change thermal properties (glass transition or thermal stability). Overall, the combination of plant-derived lignin as a filler or binder in cellulose–starch composites with a sea-animal derived nanocellulose presents an interesting new approach for the fabrication of membranes from abundant bio-derived materials. Future studies should focus on the optimization of these types of membranes for the selective and fast transport of gases needed for a variety of industrial separation processes.

Atomic-scale tandem regulation of anionic and cationic migration for long-life alkali metal batteries

Atomic-scale regulation of both cationic and anionic transport is of great significance in membrane-based separation technologies. Ionic transport regulation techniques could also play a crucial role in developing high-performance alkali metal batteries such as alkali metal-sulfur and alkali metal-selenium batteries, which suffer from the non-uniform transport of alkali metal ions and detrimental shuttling of polysulfide/polyselenide (PS) anions. These obstacles can cause severe growth of alkali metal dendrites and the irreversible consumption of active cathodes, leading to capacity decay and short cycling life. Herein, we report long-life alkali metal batteries enabled by atomic-scale tandem regulation of the migration of both alkali metal cations (Li+/Na+) and PS anions using negatively charged Ti0.87O2 nanosheets with Ti atomic vacancies. The shuttling of PS anions has been effectively eliminated via a robust electrostatic repulsion between the negatively charged nanosheets and PS anions. The negatively charged nanosheets can also regulate the migration of Li+/Na+ ions to ensure a homogeneous ion flux through efficient but light adhesion of Li+/Na+ ions within the nanosheets. The atomic Ti vacancies act as sub-nanometre pores to provide fast diffusion channels for Li+/Na+ ions. Therefore, eradication of PS shuttling and stable Li/Na-ion diffusion without compromising the fast transport of Li+/Na+ ions has been achieved for long-life alkali metal-sulfur and alkali metal-selenium batteries. This work provides a facile and effective strategy to regulate the transport of both cations and anions for developing advanced rechargeable batteries by using two-dimensional vacancy-enhanced materials.

Membranes for bioethanol production by pervaporation

Background Bioethanol as a renewable energy resource plays an important role in alleviating energy crisis and environmental protection. Pervaporation has achieved increasing attention because of its potential to be a useful way to separate ethanol from the biomass fermentation process. Results This overview of ethanol separation via pervaporation primarily concentrates on transport mechanisms, fabrication methods, and membrane materials. The research and development of polymeric, inorganic, and mixed matrix membranes are reviewed from the perspective of membrane materials as well as modification methods. The recovery performance of the existing pervaporation membranes for ethanol solutions is compared, and the approaches to further improve the pervaporation performance are also discussed. Conclusions Overall, exploring the possibility and limitation of the separation performance of PV membranes for ethanol extraction is a long-standing topic. Collectively, the quest is to break the trade-off between membrane permeability and selectivity. Based on the facilitated transport mechanism, further exploration of ethanol-selective membranes may focus on constructing a well-designed microstructure, providing active sites for facilitating the fast transport of ethanol molecules, hence achieving both high selectivity and permeability simultaneously. Finally, it is expected that more and more successful research could be realized into commercial products and this separation process will be deployed in industrial practices in the near future. Graphical abstract