Outstanding performance of capacitive deionization by a hierarchically porous 3D architectural graphene

To attain the optimal capacitive deionization (CDI) performance for brackish water desalination, an electrode should possess high electrical conductivity, large surface area, hierarchically porous carbons with three-dimensional (3D) interconnection which can provide efficient pathways for ion and electron transfer. Herein we demonstrate a novel route to prepare a hierarchically porous 3D architectural graphene by using a combination of microwave treatment and H₂O₂-assisted hydrothermal method. The physicochemical and electrochemical properties of prepared 3D porous graphene are identified by scanning/transmission electron microscopy, X-ray based spectroscopies, Raman, nitrogen adsorption-desorption, cyclic voltammetry and electrochemical impendence spectroscopy. The desalination tests are carried out by using a batch-mode CDI at 1.4 V in a 500 ppm NaCl solution. Experimental results show that 3D porous graphene has a superior specific capacitance (190 F g⁻¹) and ultrahigh electrosorption capacity (21.58 mg g⁻¹). This unique hierarchically porous 3D graphene which exhibits good electrical conductivity, efficient ion transport and lower charge transfer resistance could be one of promising electrodes for CDI in the practical applications.