Reduced graphene oxide supported cobalt-calcium phosphate composite for electrochemical water oxidation

Keunyoung Lee, Wonseok Yang, Eunji Pyo, Hyebin Choi, Yeona Cha, Seonhong Lee, Chung Soo Kim, Dong Kwon Lim, Ki Young Kwon

Research output: Contribution to journalArticlepeer-review

Abstract

We report the oxygen evolution reaction (OER) catalyst composed of cobalt–calcium phosphate on reduced graphene oxide (CoCaP/rGO). Our catalyst is prepared by the anodic electrolysis of calcium phosphate/rGO mixture loaded on indium-tin-oxide (ITO) in Co2+ aqueous solution. TEM, XPS and XRD experiments confirm that the crystal phase of calcium phosphate (CaP) is transferred into an amorphous phase of calcium oxide with phosphate (5.06 at%) after anodic electrolysis. Additionally, the main cation component of calcium is replaced by cobalt ion. The current–voltage characteristics of CoCaP/rGO showed a shoulder peak at 1.10 V vs. NHE, which originated from Co2+ to higher oxidation states (Co3+ or Co4+) and a strong wave from water oxidation higher +1.16 V vs. NHE at neutral condition (pH 7). CoCaP and CoCaP/rGO showed 4.8 and 10 mA/cm2 at 0.47 V of overpotential, respectively. The enhanced OER catalytic activity of CoCaP/rGO arises from the synergetic interaction between the amorphous phase of CoCaP and electric conducting graphene sheets.

Original languageEnglish
Article number960
JournalCatalysts
Volume11
Issue number8
DOIs
Publication statusPublished - 2021 Aug

Keywords

  • Calcium phosphate
  • Graphene
  • OER

ASJC Scopus subject areas

  • Catalysis
  • Physical and Theoretical Chemistry

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