Poly (Ionic Liquid)-Metal Organic Framework-Derived Nanoporous Carbon Membranes: Facile Fabrication and Ultrahigh Areal Capacitance.

With the rapid development of energy storage technology, the operation of portable and wearable devices is inseparable from high energy density power supplies. However, the demand for high performance supercapacitors in movable smart electronics is still restrained by their insufficient areal capacitance and limited power/energy densities. In addition, some electroactive materials, including metal oxides, conductive polymers, graphene, porous carbons, etc., are inevitable to use extra adhesives for the preparation of electrode materials. In this work, integrated hierarchical graphitic porous carbon membranes used as the electrodes without adhesives are successfully synthesized, via pyrolyzing poly(ionic liquid)s (PILs)-metal organic frameworks (MOFs) composite membranes. The asymmetric supercapacitor is assembled by the carbonized PIL-MOF composite membrane and PILs-derived porous carbon membrane, and exhibits significant areal capacitance with remarkable power and energy densities. In the two-electrode system, the areal capacitance can reach 9.5 F cm-2 with an energy density of 1.91 mWh cm-2 . In the fabricated all-solid-state supercapacitors, the areal capacitance and energy density achieved 3.2 F cm-2 and 0.65 mWh cm-2 , respectively, exceeding most reported ones. Therefore, the integrated carbon membrane electrodes with high areal capacitance reveal great potential in miniaturized devices, and further show a wider application scope through regulating PILs.

Bioinspired Gradient Covalent Organic Framework Membranes for Ultrafast and Asymmetric Solvent Transport.

Gradients play a pivotal role in membrane technologies, e.g., osmotic energy conversion, desalination, biomimetic actuation, selective separation, and more. In these applications, the compositional gradients are of great relevance for successful function implementation, ranging from solvent separation to smart devices; However, the construction of functional gradient in membranes is still challenging both in scale and directions. Inspired by the specific function-related, graded porous structures in glomerular filtration membranes, a general approach for constructing gradient covalent organic framework membranes (GCOMx) applying poly (ionic liquid)s (PILs) as template is reported here. With graded distribution of highly porous covalent organic framework (COF) crystals along the membrane, GCOMx exhibts an unprecedented asymmetric solvent transport when applying different membrane sides as the solvent feed surface during filtration, leading to a much-enhanced flux (10-18 times) of the "large-to-small" pore flow comparing to the reverse direction, verified by hydromechanical theoretical calculations. Upon systematic experiments, GCOMx achieves superior permeance in nonpolar (hexane ≈260.45 LMH bar-1) and polar (methanol ≈175.93 LMH bar-1) solvents, together with narrow molecular weight cut-off (MWCO, 472 g mol-1) and molecular weight retention onset (MWRO, <182 g mol-1). Interestingly, GCOMx shows significant filtration performance in simulated kidney dialysis, revealing great potential of GCOMx in bionic applications.