Organometallic polymers in asymmetric redox-electrode design: electrochemically-mediated ion-selective separations and enhanced energy storage

Presenter: 

Xiao Su

Authors: 

Xiao Su, Johannes Elbert, Kai-Jher Tan, Timothy F. Jamison, T. Alan Hatton

Author Affiliation: 

Department of Chemical Engineering, MIT (X.S., J.E., K.J.T., T.A.H.) Department of Chemistry, MIT (T.F.J.)

Abstract: 

Redox metallopolymers have been explored extensively for catalysis, energy storage and molecular recognition. Here, we present nanostructured electrodes functionalized with poly(vinyl)ferrocene/carbon nanotubes (PVF-CNT) as a attractive platform for the selective separation of organic micropollutants under competitive binding, with separation factors >150 based on specific functional group recognition for harmful carboxylates, sulfonates and phosphonates, and ion-capacity >200 mg/g. In tandem, cobaltocenium-based polymer counter-electrodes (PMMAECoCp-CNT) were designed as efficient cathodes to increase pseudocapacitive charge and suppress side-reactions, both enhancing energy storage capabilities (specific capacitance of 498 F/g) as well as increasing ion-selective behavior of the anode (98% selective anion recovery). Furthermore, the non-covalent functionalization of these organometallic polymers onto the electrodes grants cycling stability for over two days and >5000 cycles. This work highlights the potential of asymmetric polymer-functionalized redox-systems for electrochemical separations, and the importance of organometallic design for selectively targeting molecular-level pollutants.