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


Xiao Su


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.)


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.