Surface-microporous graphene for high-performance capacitive deionization under ultralow saline concentration

Surface microporous graphene (SMG), which had been recently invented, was demonstrated great potential as electrodes for capacitive deionization in this work. Its large amounts of surface micropores, that homogeneously distributed in graphene sheets, were observed by transmission electron microscopy and supported by N-2 adsorption/desorption measurement. This unique structure makes SMG an efficient electrode, which exhibited excellent electrochemical performance even at ultralow saline concentration. Its electrosorption capacity could reach 9.13 mg/g at 2.0 V in 50 mg/1 NaCI solution with a batch-mode recycling CDI system, which is larger than that of activated carbon (3.45 mg/g). The superior electrosorption capacity may be attributed to the surface microporous structure of SMG materials, in which the surface micropores can be accessed with negligible charge transport distance.