Review—Understanding and Controlling Charge Functions in Materials for Electrochemically Mediated Water Treatment

Abstract

Water management by electrochemical means has attracted increasing attention due to the high energetic efficiency and significantly improved water treatment efficacy of related emerging technologies. Charge functions in electronic and electrochemical materials dictate the overall water treatment performance such as selectivity, operation stability, removal capacity, and rate. Here, we elucidate the design principles of charge-functional materials for electrochemically mediated water treatment by considering fundamental performance-governing processes, including charge transport, surface adsorption, bulk ion insertion, and (photo)electrocatalysis. Furthermore, we highlight the recent development of in situ operando imaging tools for probing these critical processes that occur during water treatment, with a particular focus on functional imaging techniques capable of probing local charge-functional parameters (e.g., charge carrier diffusivity, pollutant adsorption affinity, and redox reaction rate) to establish local structure-function relationships. We conclude this review by pointing out the opportunities and challenges that warrant future research in order to further improve the performance and scale-up ability of electrochemical water treatment technologies in the broader context of the energy-environment nexus toward a sustainable zero-carbon future.

Molecularly Selective Polymer Interfaces for Electrochemical Separations

“…Electrochemical separations have garnered intense interest due to their modularity, sustainability, and applicability in critical areas of societal importance such as water purification, environmental remediation, and the recovery of value-added molecules for manufacturing. − There is a growing emphasis on the development of selective separation methods to decrease energy consumption, carbon footprint, and costs. − A notable advancement in liquid-phase electrochemical separations has been to extend the binding mechanisms beyond solely electrostatic and double-layer effects in capacitive carbon electrodes and leverage specific interfacial interactions such as hydrophobicity, conformational effects, size exclusion, and noncovalent binding at polymer-functionalized interfaces (Figure ). A transition toward these functionalized electrodes has enabled the selective separation of minority species from majority competing species, shifting the focus from the adsorption of the charged species from the solvent stream (e.g., as in desalination) to discriminating a desired target from multicomponent mixtures.…”