Rapid Inversion of Surface Charges in Heteroatom-Doped Porous Carbon: A Route to Robust Electrochemical Desalination

Jin Soo Kang, Seoni Kim, Dong Young Chung, Yoon Jun Son, Kyusik Jo, Xiao Su, Myeong Jae Lee, Hwajoo Joo, T. Alan Hatton, Jeyong Yoon, Yung Eun Sung

Research output: Contribution to journalArticlepeer-review

46 Scopus citations

Abstract

Given that a considerably large population suffers from shortage of water, there are numerous on-going efforts to turn seawater into freshwater, and electrochemical desalination processes—particularly capacitive deionization (CDI)—have gained significant attention due to their high energy efficiency and reliable performance. Meanwhile, carbonaceous electrode materials, which are most commonly used in CDI systems, have poor long-term stability due to unfavorable interactions with oxygen in saline water. Herein, rapid and vigorous inversion of surface charges in heteroatom-doped carbon electrodes, which leads to a robust operation of CDI with high desalination capacity, is reported for the first time. By carbonization of coffee wastes, nitrogen- and sulfur-codoped activated carbon with hierarchical micro/mesopores are prepared in an environmentally-friendly manner, and this carbon results in a significantly higher inverted capacity than that of various activated carbon counterparts in long-term CDI operations, without any sign of drop in performance. Investigations on the changes in physicochemical properties of the electrodes during the inversion disclose the favorable roles of nitrogen and sulfur dopants, which can be summarized as enlarging the difference between the surface charges of the two electrodes by chemical interactions with oxygen in the anode and carbon in the cathode.

Original languageEnglish
Article number1909387
JournalAdvanced Functional Materials
Volume30
Issue number9
DOIs
StatePublished - 1 Feb 2020

Bibliographical note

Funding Information:
J.S.K. and S.K. contributed equally to this work. This work was supported by the Institute for Basic Science (IBS) in the Republic of Korea (Project Code: IBS-R006-A2) and was also financially supported from the Technology Innovation Program (10082572) funded by the Ministry of Trade, Industry & Energy (MOTIE) of the Republic of Korea.

Publisher Copyright:
© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Keywords

  • capacitive deionization
  • desalination
  • heteroatom-doped carbons
  • surface charges

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