(126f) Molecular Design of Electrochemical Interfaces for Sustainable Separations in Clean Energy

Molecular design of electrochemical interfaces is critical for the development of new separation processes for the clean energy transition. Through electrochemical control, selective adsorption can be carried out without the need for any chemical eluents or physical processing, leading to modular and sustainable separations. However, significant challenges remain primarily in achieving desired molecular selectivity, especially for minority species in the presence of excess salts. Electroactive interfaces offer an attractive platform to control voltage while dictating the desired ion-selectivity.

Here, we present the tuning of redox-active interfaces for important separations related to clean energy, including critical element recovery and ammonium production. First, we discuss the structural tuning of redox-polymers for achieving finer multicomponent separations. We discuss applications ranging from the electrosorption-based recovery of critical elements to selective electrodeposition for battery recycling. Next, we discuss an electrified approach for integrating reaction and separations, especially the capture of nitrate from waste runoffs and the tandem upcycling to value-added ammonium. We design a bifunctional redox-electrode in which the electrosorbent preferentially binds nitrate during oxidation, and a co-localized electrocatalyst reduces the nitrate to ammonium during electrochemical release. We elucidate the potential and pH-responsive of redox-films for the binding of nitrate, and the underlying molecular mechanisms. We demonstrate the capability of a single electrochemical cell to greatly enhance the energy efficiency towards nitrate capture and ammonium conversion.

Overall, we highlight the promising role of electroactive interfaces for enabling energy-relevant separations and catalytic transformations.