Bismuth Nanoparticle-Embedded Porous Carbon Frameworks as a High-Rate Chloride Storage Electrode for Water Desalination

Capacitive deionization (CDI) is a promising cost-effective and low energy consumption technology for water desalination. However, most of the previous works focus on only one side of the CDI system, i.e., Na⁺ ion capture, while the other side that stores chloride ions, which is equally important, receives very little attention. This is attributed to the limited Cl^- storage materials as well as their sluggish kinetics and poor stability. In this article, we demonstrate that a N-doped porous carbon framework is capable of suppressing the phase-transformation-induced performance decay of bismuth, affording an excellent Cl^- storage and showing potential for water desalination. The obtained Bi-carbon composite (Bi/N-PC) shows a capacity of up to 410.4 mAh g^-1 at 250 mA g^-1 and a high rate performance. As a demonstration for water desalination, a superior desalination capacity of 113.4 mg g^-1 is achieved at 100 mA g^-1 with excellent durability. Impressively, the CDI system exhibits fast ion capturing with a desalination rate as high as 0.392 mg g^-1 s^-1, outperforming most of the recently reported Cl^- capturing electrodes. This strategy is applicable to other Cl^- storage materials for next-generation capacitive deionization.