The Role of Adventitious Carbon in Photo-catalytic Nitrogen Fixation by Titania

Benjamin M. Comer, Yu Hsuan Liu, Marm B. Dixit, Kelsey B. Hatzell, Yifan Ye, Ethan J. Crumlin, Marta C. Hatzell, Andrew J. Medford

Research output: Contribution to journalArticlepeer-review

45 Scopus citations

Abstract

Photo-catalytic fixation of nitrogen by titania catalysts at ambient conditions has been reported for decades, yet the active site capable of adsorbing an inert N2 molecule at ambient pressure and the mechanism of dissociating the strong dinitrogen triple bond at room temperature remain unknown. In this work in situ near-ambient-pressure X-ray photo-electron spectroscopy and density functional theory calculations are used to probe the active state of the rutile (110) surface. The experimental results indicate that photon-driven interaction of N2 and TiO2 is observed only if adventitious surface carbon is present, and computational results show a remarkably strong interaction between N2 and carbon substitution (C∗) sites that act as surface-bound carbon radicals. A carbon-assisted nitrogen reduction mechanism is proposed and shown to be thermodynamically feasible. The findings provide a molecular-scale explanation for the long-standing mystery of photo-catalytic nitrogen fixation on titania. The results suggest that controlling and characterizing carbon-based active sites may provide a route to engineering more efficient photo(electro)-catalysts and improving experimental reproducibility.

Original languageEnglish (US)
Pages (from-to)15157-15160
Number of pages4
JournalJournal of the American Chemical Society
Volume140
Issue number45
DOIs
StatePublished - Nov 14 2018
Externally publishedYes

All Science Journal Classification (ASJC) codes

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

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