Bioinspired Chloride-Assisted Protein Channels: Enhancing Proton Transport for Sustainable Energy Harvesting from Acidic Wastewater

Highly efficient proton transfer in biological processes has driven the pursuit of synthetic analogs; however, replicating high proton permeance in natural systems remains a significant challenge. Herein, inspired by the function of the ClC-ec1 protein, we report the design of Cl--assisted proton transport channels within a hybrid membrane composed of covalent organic frameworks (COFs) integrated with aramid nanofibers (ANFs). By leveraging buffer layer-mediated interfacial polymerization and the flocculation behavior of ANF in aqueous environments, we establish robust hydrogen-bonding interactions between COFs and ANFs. The hydride material enables Cl- binding, significantly accelerating proton transport in a manner similar to that of the ClC-ec1 protein channel. In the presence of a small concentration of Cl- ions (0.1% of the proton concentration), the proton permeation rate is enhanced approximately by 3 times, reaching 9.8 mol m-2 h-2. Notably, the membrane facilitates sustainable osmotic power generation from acidic wastewater, delivering an output power density of 434.8 W m-2. Theoretical calculations revealed that ANF preferentially binds Cl-, promoting proton hopping and lowering the energy barrier for proton transport. This study establishes a new paradigm for bioinspired ion-assisted proton transport, presenting an approach for sustainable energy harvesting from acidic wastewater.