Mechanistic Investigation with Kinetic Parameters on Water Oxidation Catalyzed by Manganese Oxide Nanoparticle Film

Hongmin Seo, Kyoungsuk Jin, Sunghak Park, Kang Hee Cho, Heonjin Ha, Kang Gyu Lee, Yoon Ho Lee, Dang Thanh Nguyen, Hyacinthe Randriamahazaka, Jong Sook Lee, Ki Tae Nam

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)

Abstract

Electrochemical water oxidation is a key counter reaction in obtaining value-added chemicals by reduction in aqueous solution. However, slow kinetics is a problem in this process, so the quantitative analysis of kinetic parameters is necessary to design film-type electrocatalysts. Although electrochemical impedance spectroscopy (EIS) has been proven to be a powerful tool in analyzing sparsely loaded catalysts on electrically conducting supporters, it turned out that film-type catalysts above 100 nm thickness are challenging to analyze with conventional models. Here, we propose a new transmission line model that was implemented with a Havriliak-Negami (H-N) capacitor and Warburg element. We successfully extracted meaningful kinetic parameters, such as the reaction rate constant at active sites and transport parameters across the film. We utilized this model to analyze monodisperse sub-10 nm partially oxidized MnO nanoparticles (p-MnO NPs) operating with superb activity under neutral pH. From this analysis, we revealed that protons are involved in transport on the surface of p-MnO NPs, explained the rationale for the optimum thickness, and correlated the reaction rate constant (22.1 s-1 for a 300 nm-thick film at 1.35 V vs NHE) with the kinetic parameters obtained from electrokinetic analysis.

Original languageEnglish
Pages (from-to)10595-10604
Number of pages10
JournalACS Sustainable Chemistry and Engineering
Volume7
Issue number12
DOIs
Publication statusPublished - 2019 Jun 17
Externally publishedYes

Keywords

  • Charge transport process
  • Electrocatalysts
  • Electrochemical impedance spectroscopy
  • Manganese oxide-based nanoparticles
  • Water oxidation

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry
  • Chemical Engineering(all)
  • Renewable Energy, Sustainability and the Environment

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