Catalytic reduction of proton, oxygen and carbon dioxide with cobalt macrocyclic complexes

Kentaro Mase, Shoko Aoi, Kei Ohkubo, Shunichi Fukuzumi

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18 Scopus citations


The conversion of solar energy into chemical energy by the reduction of small molecules provides a promising solution for the effective energy storage and transport. In this manuscript, we have highlighted our recent researches on the catalysis of cobalt-macrocycle complexes for the reduction of O2, proton and CO2. We have successfully clarified the reaction mechanisms of catalytic O2 reduction with cobalt phthalocyanine (CoII(Pc)) and cobalt chlorin (CoII(Ch)) based on detailed kinetic study under homogeneous conditions. The presence of proton-accepting moieties on these macrocyclic ligands enhances the electron-accepting ability, leading to the efficient catalytic two-electron reduction of O2 to produce hydrogen peroxide (H2O2) with high stability and less overpotential in acidic solutions. When CoII(Ch) is adsorbed on multi-walled carbon nanotubes (MWCNTs) and employed as an electrocatalyst, CO2 was successfully reduced to form CO with a Faradaic efficiency of 89% at an applied potential of -1.1 V vs. NHE in an aqueous solution. Finally, photocatalytic H2 evolution was attained from ascorbic acid with CoII(Ch) as a catalyst and [Ru(bpy)3]2+ (bpy = 2,2'-bipyridine) as a photocatalyst via a one-photon two-electron process.

Original languageEnglish
Pages (from-to)935-949
Number of pages15
JournalJournal of Porphyrins and Phthalocyanines
Issue number8-11
StatePublished - 1 Aug 2016

Bibliographical note

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© 2016 World Scientific Publishing Company.


  • carbon dioxide reduction
  • cobalt complexes
  • oxygen reduction
  • photocatalytic reaction
  • proton reduction
  • proton-coupled electron-transfer catalysis


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