Carbon nanotubes in-situ cross-linking the activated carbon electrode for high-performance capacitive deionization

Abstract

While the activated carbon (AC) electrodes applied in the field of capacitive deionization (CDI) are mostly prepared by slurry-coating methods, they have long been suffering from the unideal electron transfer rates and exfoliation during long-term operation. Herein, we report an AC electrode modification method involving carbonizing less-conductive binders and in-situ grafting of carbon nanotubes (CNTs) on entire AC electrodes via a one-step vacuum chemical vapor deposition (CVD) process. The in-situ grafted CNTs showed a much more homogeneous distribution in AC electrodes, which functioned as conductive glue bridging the AC granules and intimately formed a solid and highly conductive carbon framework. The as-prepared AC electrode with grafted CNTs had a superior salt adsorption capacity of 15.6 mg NaCl g−1 with prominent long-term stability and increased current efficiency (by 70%) compared with traditional AC electrodes. The boosted CDI performance should be ascribed to the unique structure and electrical properties of the electrode. This work provides an efficient and facile alternative to preparing tuned AC electrodes for viable water treatment technologies, which is of great potential to be applied in many attractive fields such as catalysis, energy conversion and storage.