High-Performance Capacitive Deionization via Manganese Oxide-Coated, Vertically Aligned Carbon Nanotubes

Wenbo Shi, Xuechen Zhou, Jinyang Li, Eric R. Meshot, André D. Taylor, Shu Hu, Jae Hong Kim, Menachem Elimelech, Desiree L. Plata

Research output: Contribution to journalArticle

Abstract

Discovering electrode materials with exceptional capacitance, an indicator of the ability of a material to hold charge, is critical for developing capacitive deionization devices for water desalination. Maganese oxides (MnOx) have shown promise as capacitive electrode materials, but they exhibit a trade-off in which a higher loading of the active MnOx comes at the cost of lower conductivity. To address this challenge and achieve high salt adsorption, we fabricated electrodes comprising vertically aligned core-shell nanostructures using atomic layer deposition (ALD) to coat thin films of MnOx onto vertically aligned carbon nanotubes (VACNTs). The inherently hierarchical, anisotropic, three-dimensional macroporous structure of VACNTs and the tunable coating, a hallmark of ALD, enabled co-optimization of the hybrid material's specific capacitance with respect to mass and geometric area. The specific capacitance was optimized in this study to 215 ± 7 F/g and 1.1 ± 0.1 F/cm2 in a 1 M NaCl electrolyte at a scan rate of 5 mV/s. This material exhibited a remarkable sodium ion adsorption capacity of 490 ± 30 μmol of Na/g of material (2-fold higher than that of pristine VACNTs) at a functioning voltage of 1.2 V, which may ultimately enable expanded desalination applications of capacitive deionization.

Original languageEnglish (US)
Pages (from-to)692-700
Number of pages9
JournalEnvironmental Science and Technology Letters
Volume5
Issue number11
DOIs
StatePublished - Nov 13 2018

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ASJC Scopus subject areas

  • Environmental Chemistry
  • Ecology
  • Water Science and Technology
  • Waste Management and Disposal
  • Pollution
  • Health, Toxicology and Mutagenesis

Cite this

Shi, W., Zhou, X., Li, J., Meshot, E. R., Taylor, A. D., Hu, S., Kim, J. H., Elimelech, M., & Plata, D. L. (2018). High-Performance Capacitive Deionization via Manganese Oxide-Coated, Vertically Aligned Carbon Nanotubes. Environmental Science and Technology Letters, 5(11), 692-700. https://doi.org/10.1021/acs.estlett.8b00397