A Facile Microwave-Assisted Method to Prepare Highly Electrosorptive Reduced Graphene Oxide/Activated Carbon Composite Electrode for Capacitive Deionization

Reduced graphene oxide (rGO)/activated carbon (AC) composites with a hierarchically porous structure are prepared in the presence of ethylene glycol (EG) under microwave irradiation and exhibit excellent electrosorption properties. In this novel microwave-assisted process, EG plays multiple roles such as solvent, GO reducing reagent, microwave absorber, rGO aggregation preventer, and surface wettability enhancer. In addition, the reaction system can be rapidly heated owing to the high dissipation factor of EG. As a result, GO can be rapidly reduced and in situ uniformly deposited on the AC surface. 3D porous structures can be obtained due to the explosion of the functional groups in GO. Additionally, EG causes electrostatic repulsion between the rGO layers, thereby preventing aggregation and forming a 3D hierarchical structure. Furthermore, the ethanedial that stems from oxidized ethylene glycol interacts with the graphene sheets, enhancing the wettability and conductivity of the composite electrodes, and subsequently increasing the efficiency of the charge-transfer process. rGO/AC composites electrode fabricated using this process exhibit an outstanding electrosorption capacity of 18.6 +/- 1.2 mg g(-1), making them an excellent candidate for industrial applications.