Understanding the Dynamics of Molecular Water Oxidation Catalysts with Liquid-Phase Transmission Electron Microscopy: The Case of Vitamin B12

Zahra Abdi, S. Esmael Balaghi, Alla S. Sologubenko, Marc Georg Willinger, Matthias Vandichel, Jian Ren Shen, Suleyman I. Allakhverdiev, Greta R. Patzke, Mohammad Mahdi Najafpour

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

Cobalt compounds are intensely explored as efficient catalysts for the oxygen evolution reaction (OER). Since vitamin B12 is a soluble cobalt compound with high enzymatic activity, evaluating its OER activity is of relevance for biomimetic catalyst research. In this work, the temporal evolution of a homogenous vitamin B12 catalyst in the early stages of OER was investigated by an advanced combination of in situ electrochemical liquid transmission electron microscopy (EC-LTEM), in situ UV-vis spectroelectrochemistry, and extended X-ray absorption fine structure (EXAFS) methods. For the first time, we provided direct evidence of diffuse layer dynamics on the working electrode interface. The results suggested that the formation of cobalt oxyphosphate nanoparticles on the working electrode interface and in the presence of phosphate buffer is the initial stage of the catalytic pathway. Computational results confirmed that the ligand oxidation pathway could occur at potentials below the OER thermodynamic barrier (1.23 V vs reversible hydrogen electrode (RHE)), which leads to a Co ion leaching into the electrolyte. This study showed that investigation of the apparent molecular mechanisms of OER with metal complexes requires careful analyses. We illustrate the high precision and sensitivity of EC-LTEM under operational conditions to monitor heterogeneous catalysts generated during OER and to evaluate their actual roles in the catalytic process.

Original languageEnglish
Pages (from-to)9494-9505
Number of pages12
JournalACS Sustainable Chemistry and Engineering
Volume9
Issue number28
DOIs
Publication statusPublished - Jul 19 2021

Keywords

  • cobalt
  • in situ electrochemical liquid TEM
  • oxygen evolution reaction
  • renewable energy
  • vitamin B

ASJC Scopus subject areas

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

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