Ni-Fe Oxides/TiO2 Heterojunction Anodes for Reactive Chlorine Generation and Mediated Water Treatment

Evandi Rahman, Sukhwa Hong, Jaesang Lee, Seok Won Hong, Kangwoo Cho

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

Reactive chlorine-mediated electrochemical water treatment necessitates selective chlorine evolution reaction (ClER) versus parallel oxygen evolution reaction (OER) in mild pH (7-10), with minimal deployments of precious electrocatalysts. This study reports Ni0.33Fe0.67Oy/TiO2 heterojunction anode prepared by a straightforward sol-gel coating with thermal decomposition at 425 °C. The ClER current efficiency (CE, 70%) and energy efficiency (2.3 mmol W h-1) were comparable to benchmarking Ir7Ta3Oy/TiO2 at 30 mA cm-2 in 50 mM NaCl solutions with near-neutral pH. Correlations of ClER CE of variable NixFe1-xOy/TiO2 (x: 0.33, 0.8-1) with the flat-band potential and p-band center, as experimental descriptors for surface charge density, nominated the outer TiO2 to be the active ClER center. The underlying Ni0.33Fe0.67Oy, characterized as biphasic NiFe2O4 and NiO, effectively lowered the O binding energy of TiO2 by electronic interaction across the junction. The OER activity of Ni0.33Fe0.67Oy superior to the other Fe-doped Ni oxides suggested that the conductive OER intermediates generated on Ni0.33Fe0.67Oy could also facilitate the ClER as an ohmic contact. Stability tests and NH4+ degradation in synthetic and real wastewater confirmed the feasibility of Ni0.33Fe0.67Oy/TiO2 heterojunction anode for mediated water treatments in mild pH.

Original languageEnglish
Pages (from-to)17867-17878
Number of pages12
JournalACS Applied Materials and Interfaces
Volume15
Issue number14
DOIs
Publication statusPublished - 2023 Apr 12

Bibliographical note

Funding Information:
This work was financially supported by National Research Foundation of Korea (NRF) grants (2022R1A2C4001228, 2022M3H4A4097524, and 2021M3I3A1084818).

Publisher Copyright:
© 2023 American Chemical Society

Keywords

  • Ni−Fe oxide
  • TiO
  • chlorine evolution reaction
  • descriptor
  • water treatment

ASJC Scopus subject areas

  • General Materials Science

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