Extraordinary capacitive deionization performance of highly-ordered mesoporous carbon nano-polyhedra for brackish water desalination

Abstract

Brackish water desalination using capacitive deionization (CDI) offers a promising solution to solve water scarcity. Activated carbons are frequently utilized as commercial electrode materials for CDI, however some limitations in their performance have prevented the practical implementation of CDI. The development of mesostructured carbons that can exceed the performance of commercial activated carbons is highly desirable. Herein, we report the first preparation of carbon nano-polyhedra with three-dimensional (3D) open highly ordered mesostructures as electrode materials for CDI. Owing to their nano-polyhedral structure with 3D open, highly ordered and well-interconnected mesochannels, the obtained mesoporous carbon materials possess large surface area for ion adsorption and shortened pathways for ion diffusion, giving rise to a high desalination capacity of 14.58 mg g⁻¹, fast desalination rate, and stable cycling ability. More importantly, the desalination capacity of our mesoporous carbon nano-polyhedra is the highest among all mesoporous carbon-based CDI electrodes reported to date. It is believed that our mesoporous carbon nano-polyhedra would be promising for practical CDI application.