In-situ synthesis of self-coated bismuth-carbon composite electrode for chloride-storage in capacitive deionization

Abstract

Bismuth-based materials as an efficient Cl- storage electrode in capacitive deionization (CDI) technology possess a high affinity for chloride ions. However, their performance is significantly limited owing to the frequent volume expansion of bismuth (Bi) nanoparticles during the electro-sorption process. Herein, a facile synthesis strategy of a self-coated bismuth-carbon composite (BiAC@C) was fabricated through one-step carbonization of commercial bismuth acetate. The yolk-shell nanostructure-like BiAC@C uniformly sandwiched the Bi nanoparticles in the porous carbon framework, which not only provided a reinforcing “carbon skeleton” for constraining Bi nanoparticles in spatial, but also facilitated the ions diffusion and better electronic conductivity, supplying an superior Cl- removal with enhanced ability for water desalination. Results show that a superior Cl- removal capacity of the synthesized BiAC@C composite electrodes was ∼109.63 mg g−1 at 20 mA g−1, substantially higher than that of the most Cl- capturing electrodes recently reported. Moreover, such a capacity could keep a durability that still retains 80.53 % of its initial capacity after 50 continuous treatment cycles under current density of 30 mA g−1, and it is much higher than 29.11 % of the pure Bi electrode. It is expected that the prepared BiAC@C composite could be a promising alternative material for the extraction of Cl- from wastewater.