title: Engineered Asymmetric Heterogeneous Membrane: A Concentration-Gradient-Driven Energy Harvesting Device.
abstract: Engineered asymmetric membranes for intelligent molecular and ionic transport control at the nanoscale have gained significant attention and offer prospects for broad application in nanofluidics, energy conversion, and biosensors. Therefore, it is desirable to construct a high-performance heterogeneous membrane capable of coordinating highly selective and rectified ionic transport with a simple, versatile, engineered method to mimic the delicate functionality of biological channels. Here, we demonstrate an engineered asymmetric heterogeneous membrane by combining a porous block copolymer (BCP) membrane, polystyrene-b-poly(4-vinylpyridine) (PS48400-b-P4VP21300), with a track-etched asymmetric porous polyethylene terephthalate membrane. The introduction of chemical, geometrical, and electrostatic heterostructures provides our heterogeneous membrane with excellent anion selectivity and ultrahigh ionic rectification with a ratio of ca. 1075, which is considerably higher than that of existing ionic rectifying systems. This anion-selective heterogeneous membrane was further developed into an energy conversion device to harvest the energy stored in an electrochemical concentration gradient. The concentration polarization phenomenon that commonly exists in traditional reverse electrodialysis can be eliminated with an asymmetric bipolar structure, which considerably increases the output power density. This work presents an important paradigm for the use of versatile BCPs in nanofluidic systems and opens new and promising routes to various breakthroughs in the fields of chemistry, materials science, bioscience, and nanotechnology.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Zhang
authors.forename: Xiang-Yu
authors.initials: XY
authors.lastname: Kong
authors.forename: Kai
authors.initials: K
authors.lastname: Xiao
authors.affiliation: Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, Beijing Normal University , Beijing 100875, P. R. China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Liu
authors.forename: Ganhua
authors.initials: G
authors.lastname: Xie
authors.forename: Pei
authors.initials: P
authors.lastname: Li
authors.forename: Jie
authors.initials: J
authors.lastname: Ma
authors.forename: Ye
authors.initials: Y
authors.lastname: Tian
authors.forename: Liping
authors.initials: L
authors.lastname: Wen
authors.forename: Lei
authors.initials: L
authors.lastname: Jiang