High Spin State Promotes Water Oxidation Catalysis at Neutral pH in Spinel Cobalt Oxide

Lin Ma, Sung Fu Hung, Liping Zhang, Weizheng Cai, Hong Bin Yang, Hao Ming Chen, Bin Liu*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

In this work, we present Co3O4 quantum dots (QDs) as a highly efficient and stable oxygen evolution reaction (OER) catalyst at neutral pH. The Co3O4 QDs with a mean size of 5 nm were synthesized by reacting cobalt acetate with benzyl alcohol in the presence of ammonia under reflux conditions. The as-synthesized Co3O4 QDs show extraordinary water oxidation activity with onset overpotential as low as 398 mV and mass activity as high as 567 A/g (at 1.75 V vs RHE) in a 0.2 M phosphate buffer electrolyte (pH ∼7), which are among the most efficient Earth-abundant OER catalysts at neutral pH reported in the literature, reaching a stable current density of 10 mA/cm2 at an overpotential of ∼490 mV with a Tafel slope of 80 mV/decade. Through in-depth investigations by X-ray photoelectron spectroscopy and X-ray absorption spectroscopy, the high spin Co2+ and Co3+ cations on the surface of Co3O4 QDs were found to be important to promote the OER kinetics at neutral pH.

Original languageEnglish
Pages (from-to)1441-1445
Number of pages5
JournalIndustrial and Engineering Chemistry Research
Volume57
Issue number5
DOIs
StatePublished - 2018

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