Zwitterionic Polymer Modified Porous Carbon for High-Performance and Antifouling Capacitive Desalination

Capacitive deionization (CDI) is an emerging technology for effective brackish water desalination to address fresh water scarcity. It is of great interest due to its high energy efficiency, environmental friendliness, and low-cost operation compared with traditional desalination technologies. However, electrode fouling, caused by dissolved organic matter and resulting in reduction of electrode electrosorption capacity and device lifespan, is an impediment to practical application of CDI. Herein, we report a novel salty water desalination electrode with excellent antifouling properties. The antifouling electrode is prepared by coating zwitterionic polymer brushes, i.e., poly(sulfobetaine methacrylate) (SBMA), on porous carbon (PC) via surface-initiated atom transfer radical polymerization. The successful coating of zwitterionic polymer on PC surface is confirmed by transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, and other characterizations. Coating with polySBMA did not affect the electrosorption capacity of PC electrodes and imparted antifouling properties (versus fouling by model foulant bovine serum albumin) during long-term salt removal tests (100 desalination/regeneration cycles). This is an important step toward practical application of capacitive deionization technology for brackish water desalination.