On the active sites for the oxygen reduction reaction catalyzed by graphene-based materials

Ljubisa R. Radovic, Adolfo J.A. Salgado-Casanova, Camila V. Mora-Vilches

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

At the heart of the mechanism and efficiency of oxygen reduction is the identification of active sites in graphene-based electrocatalysts ranging from carbon blacks to heat-treated phthalocyanines. Distinction between the transfer of two or four electrons points to O2 dissociation as the essential mechanistic clue; here we examine this issue by exploiting the analogy with carbon oxidation, where production of CO vs. CO2 has long been a crucial point. We compare our computational results with experimental evidence on the behavior of graphene as well as its N-, B- and transition-metal-doped counterparts. Electron transfer is revealed to occur readily through a carbene-type site upon oxygen surface rearrangement. Whether adsorbed O2 dissociates depends on proton transfer occurring before or after the stabilization of a peroxy intermediate; this in turn depends on electron density distribution at and around the active site. A good correlation exists between spin density at the active site and O2 adsorption energy.

Original languageEnglish (US)
Pages (from-to)389-398
Number of pages10
JournalCarbon
Volume156
DOIs
StatePublished - Jan 2020

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Materials Science(all)

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