Bi-directional water-stream behavior on multifunctional membrane for simultaneous energy generation and water purification.

Hydro-electric nanogenerators have been previously proposed to recycle various water resources (e.g., sea water, ground water, sweat, or rain) and polluted water. However, as the conventional hydro-electric nanogenerator only utilizes water resources, it cannot provide a fundamental solution for water recycling. In this study, we propose a water purification membrane that can simultaneously generate electricity during the purification process (Electricity generation and purification membrane, EPM) for water recycling. As polluted water passes through the EPM, the water is purified in the perpendicular direction, while electricity is simultaneously produced in the horizontal direction by the movement of ions. Notably, EPM exhibited high energy generation performances (maximum power 16.44 μW and energy 15.16 mJ) by the streaming effect of water-streaming carbon nanotubes (CNT) and ion-permselective effect of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). Moreover, by using poly(acrylic acid)/carboxymethyl cellulose (PAA/CMC) binder to EPM, we substantially improved the energy generation performance and long-term stability and provided outstanding mechanical stability, regardless of the acidity of the water source (pH 1-10). More importantly, EPM exhibited the water purification characteristics of >90% rejection of sub-10 nm pollutants and potentiality of angstrom level cation rejection, with simultaneous and continuous energy generation. Overall, this study proposed an efficient EPM model, which can be potentially used as a next-generation renewable energy generation approach, thus laying the foundation for effective utilization of polluted water resources. This article is protected by copyright. All rights reserved.