Enhanced electrochemical and capacitive deionization performances of single-layer graphene oxide/nitrogen-doped porous carbon/activated carbon fiber composite electrodes

Abstract

Capacitive deionization (CDI) is an electrosorption desalination technology based on electrode charge surface, where CDI electrode materials play important roles in efficient desalination processes. This study created and manufactured innovative single-layer graphene oxide (SGO), nitrogen-doped porous carbon (NPC), and activated carbon fiber (ACF) composites to produce SGO/NPC/ACF electrode materials with electrochemical and CDI performances. The SGO/NPC/ACF electrode combined the stability of NPC with the high conductivity of SGO to yield enhanced electrochemical and CDI activities. The samples have been characterized using XRD, SEM, and XPS. The electrochemical performance was tested by cyclic voltammetry and electrochemical impedance spectroscopy methods. As a result, SGO/NPC/ACF showed a high specific capacitance of 323.08 F g−1. The specific surface area of SGO/NPC/ACF is 1154.91 m2 g−1. The salt adsorption capacity (SAC) of the SGO/NPC/ACF composite electrode is 16.25 mg g−1, which is about 1.5 times (10.70 mg g−1) that of the ACF electrode. After fifty adsorption/desorption treatments, the SAC retention of the SGO/NPC/ACF electrode is 1.6 times higher than that of ACF. Our work also provides a theoretical basis for the efficient development of green carbon-based composites. Therefore, the SGO/NPC/ACF electrode has good cycle stability and reproducibility, which is expected to become a practical CDI electrode material for desalination.