Enhanced electrical and mass transfer characteristics of acid-treated carbon nanotubes for capacitive deionization

• We prepared the acid treatment CNT and it shows enhanced the electrochemical capacitance.
• Through the XPS, XRD data, we can know that surface wettability and crystallinity are increased by acid treatment.
• The structure like shorten length and defect of CNT improved access of the ions, increasing available sites for adsorption.

Capacitive deionization (CDI) has attracted significant attention for the next generation water treatment due to its low energy consumption and environment friendly properties in comparison to widely established methods. For CDI technology to move forward, however, the development of carbon electrodes having superb electrosorption behavior is essential. In this study, we demonstrate the functionalization of carbon nanotubes (CNTs) via acid treatment shows enhanced electrochemical characteristics and effectively improves the wettability of the acid-treated CNTs (a-CNTs) via the addition of oxygen functional groups, leading to a higher electric double layer capacitance. Furthermore, defect formation in a-CNTs increases the conductivity and decreases the mass transfer resistance during CDI operation. CDI measurements confirmed a 270% increase in performance of a-CNTs in contrast to pristine CNTs (p-CNTs), attributable to the improved characteristics outlined above.