Elucidation of Factors That Govern the 2e-/2H+vs 4e-/4H+Selectivity of Water Oxidation by a Cobalt Corrole

Biswajit Mondal, Samir Chattopadhyay, Subal Dey, Atif Mahammed, Kaustuv Mittra, Atanu Rana, Zeev Gross, Abhishek Dey

Research output: Contribution to journalArticlepeer-review

24 Scopus citations

Abstract

Considering the importance of water splitting as the best solution for clean and renewable energy, the worldwide efforts for development of increasingly active molecular water oxidation catalysts must be accompanied by studies that focus on elucidating the mode of actions and catalytic pathways. One crucial challenge remains the elucidation of the factors that determine the selectivity of water oxidation by the desired 4e-/4H+ pathway that leads to O2 rather than by 2e-/2H+ to H2O2. We now show that water oxidation with the cobalt-corrole CoBr8 as electrocatalyst affords H2O2 as the main product in homogeneous solutions, while heterogeneous water oxidation by the same catalyst leads exclusively to oxygen. Experimental and computation-based investigations of the species formed during the process uncover the formation of a Co(III)-superoxide intermediate and its preceding high-valent Co-oxyl complex. The competition between the base-catalyzed hydrolysis of Co(III)-hydroperoxide [Co(III)-OOH]- to release H2O2 and the electrochemical oxidation of the same to release O2 via [Co(III)-O2•]- is identified as the key step determining the selectivity of water oxidation.

Original languageEnglish
Pages (from-to)21040-21049
Number of pages10
JournalJournal of the American Chemical Society
Volume142
Issue number50
DOIs
StatePublished - 16 Dec 2020
Externally publishedYes

ASJC Scopus subject areas

  • Catalysis
  • Chemistry (all)
  • Biochemistry
  • Colloid and Surface Chemistry

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