Microporous Polyelectrolyte Complexes by Hydroplastic Foaming.

Polyelectrolyte complexes (PECs) have emerged as an attractive category of materials for their water processability and some similarities to natural biopolymers. Herein, we employ the intrinsic hydroplasticity of PEC materials to enable the generation of porous structures with the aid of gas foaming. Such foamable materials are fabricated by simply mixing polycation, polyanion, and a UV-initiated chemical foaming agent in an aqueous solution, followed by molding into thin films. The gas foaming of the PEC films can be achieved upon exposure to UV illumination under water, where the films are plasticized and the gaseous products from the photolysis of foaming agents afford the formation, expanding, and merging of numerous bubbles. The porosity and morphology of the resulting porous films can be customized by tuning film composition, foaming conditions, and especially the degree of plasticizing effect, illustrating the high flexibility of this hydroplastic foaming method. Due to the rapid initiation of gas foaming, the present method enables the formation of porous structures via an instant one-step process, much more efficient than those existing strategies for porous PEC materials. More importantly, such a pore-forming mechanism might be extended to other hydroplastic materials (e.g., biopolymers) and help to yield hydroplasticity-based processing strategies.

Two-Dimensional Nanofluidic Membranes with Intercalated In-Plane Shortcuts for High-Performance Blue Energy Harvesting.

Two-dimensional nanofluidic membranes offer great opportunities for developing efficient and robust devices for ionic/water-nexus energy harvesting. However, low counterion concentration and long pathway through limited ionic flux restrict their output performance. Herein, it is demonstrated that rapid diffusion kinetics can be realized in two-dimensional nanofluidic membranes by introducing in-plane holes across nanosheets, which not only increase counterion concentration but also shorten pathway length through the membranes. Thus, the holey membranes exhibited an enhanced performance relative to the pristine ones in terms of osmotic energy conversion. In particular, a biomimetic multilayered membrane sequentially assembled from pristine and holey sections offers an optimized combination of selectivity and permeability, therefore generating a power density up to 6.78 W m-2 by mixing seawater and river water, superior to the majority of the state-of-the-art lamellar nanofluidic membranes. This work highlights the importance of channel morphologies and presents a general strategy for effectively improving ion transport through lamellar membranes for high-performance nanofluidic devices.

Superstructured Optoionic Heterojunctions for Promoting Ion Pumping Inspired by Photoreceptor Cells.

Photoreceptor cells of vertebrates feature ultrastructural membranes interspersed with abundant photosensitive ion pumps to boost signal generation and realize high gain in dim light. In light of this, superstructured optoionic heterojunctions (SSOHs) with cation-selective nanochannels are developed for manipulating photo-driven ion pumping. A template-directed bottom-up strategy is adopted to sequentially assemble graphene oxide (GO) and PEDOT:PSS into heterogeneous membranes with sculptured superstructures, which feature programmable variation in membrane topography and contain a donor-acceptor interface capable of maintaining electron-hole separation upon photoillumination. Such elaborate design endows SSOHs with a much higher magnitude of photo-driven ion flux against a concentration gradient in contrast to conventional optoionic membranes with planar configuration. This can be ascribed to the buildup of an enhanced transmembrane potential owing to the effective separation of photogenerated carriers at the heterojunction interface and the increase of energy input from photoillumination due to a synergistic effect of reflection reduction, broad-angle absorption, and wide-waveband absorption. This work unlocks the significance of membrane topographies in photo-driven transmembrane transportation and proposes such a universal prototype that could be extended to other optoionic membranes to develop high-performance artificial ion pumps for energy conversion and sensing.

MOF-Decorated Poly(tetrafluoroethylene) Membranes with Underwater Superoleophobicity for Extracting Osmotic Energy from Oily Wastewater Effluents.

Industrial processes generate huge volumes of oily saline wastewater. Instead of being sent to the drainage system immediately, extracting osmotic energy from these effluents represents a promising means to reuse these wastes and contributes to mitigate the ever-growing energy crisis. Herein, an MOF-decorated PTFE membrane is engineered to extract osmotic energy from oily wastewaters. Copper hydroxide nanowires (CHNs) are intertwined with polystyrenesulfonate sodium (PSS), deposited onto a poly(tetrafluoroethylene) (PTFE) membrane, and thereafter used as metal precursors to in situ generate HKUST-1 doped with negative charges. The resulting HKUST-1PSS@PTFE hybrid membrane possesses abundant angstrom-scale channels capable of transporting cations efficiently and features a hierarchically structured surface with underwater superoleophobicity. The energy conversion performance of the HKUST-1PSS3.5@PTFE membrane can reach an output power density of 6.21 W m-2 at a 50-fold NaCl gradient, which is superior to those of pristine PTFE membranes. Once exposed to oily saline wastewater, the HKUST-1PSS@PTFE membrane can exhibit an excellent oil-repellent ability, thus contributing to sustain its osmotic energy harvesting. This work may promote the development of antifouling osmotic energy harvesters with a long working life and pave the way to fully exploit oily wastewater effluents as valuable energy sources.

Dibromidobis[1-(2-bromo-benz-yl)-3-(pyrimidin-2-yl)-1H-imidazol-2(3H)-one]copper(II).

In the title complex, [CuBr(2)(C(14)H(11)BrN(4)O)(2)], the Cu(II) ion is located on an inversion centre and is coordinated by two ketonic O atoms, two N atoms and two Br atoms, forming a distorted octahedral coordination environment. The two carbonyl groups are trans positioned with C=O bond lengths of 1.256 (5) Å, in agreement with a classical carbonyl bond. The Cu-O bond length is 2.011 (3) Å. The two bromo-benzyl rings are approximately parallel to one another, forming a dihedral angle of 70.1 (4)° with the coordination plane.