Highly Active NiO Photocathodes for H2O2 Production Enabled via Outer-Sphere Electron Transfer

Onyu Jung, Michael L. Pegis, Zixuan Wang, Gourab Banerjee, Coleen T. Nemes, William L. Hoffeditz, Joseph T Hupp, Charles A. Schmuttenmaer, Gary W Brudvig, James M. Mayer

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Tandem dye-sensitized photoelectrosynthesis cells are promising architectures for the production of solar fuels and commodity chemicals. A key bottleneck in the development of these architectures is the low efficiency of the photocathodes, leading to small current densities. Herein, we report a new design principle for highly active photocathodes that relies on the outer-sphere reduction of a substrate from the dye, generating an unstable radical that proceeds to the desired product. We show that the direct reduction of dioxygen from dye-sensitized nickel oxide (NiO) leads to the production of H2O2. In the presence of oxygen and visible light, NiO photocathodes sensitized with commercially available porphyrin, coumarin, and ruthenium dyes exhibit large photocurrents (up to 400 μA/cm2) near the thermodynamic potential for O2/H2O2 in near-neutral water. Bulk photoelectrolysis of porphyrin-sensitized NiO over 24 h results in millimolar concentrations of H2O2 with essentially 100% faradaic efficiency. To our knowledge, these are among the most active NiO photocathodes reported for multiproton/multielectron transformations. The photoelectrosynthesis proceeds by initial formation of superoxide, which disproportionates to H2O2. This disproportionation-driven charge separation circumvents the inherent challenges in separating electron-hole pairs for photocathodes tethered to inner sphere electrocatalysts and enables new applications for photoelectrosynthesis cells.

Original languageEnglish
Pages (from-to)4079-4084
Number of pages6
JournalJournal of the American Chemical Society
Volume140
Issue number11
DOIs
Publication statusPublished - Mar 21 2018

Fingerprint

Photocathodes
Nickel oxide
Coloring Agents
Electrons
Dyes
Porphyrins
Oxygen
Ruthenium
Thermodynamics
Superoxides
Electrocatalysts
Photocurrents
Light
Current density
nickel monoxide
Water
Substrates

ASJC Scopus subject areas

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

Cite this

Jung, O., Pegis, M. L., Wang, Z., Banerjee, G., Nemes, C. T., Hoffeditz, W. L., ... Mayer, J. M. (2018). Highly Active NiO Photocathodes for H2O2 Production Enabled via Outer-Sphere Electron Transfer. Journal of the American Chemical Society, 140(11), 4079-4084. https://doi.org/10.1021/jacs.8b00015

Highly Active NiO Photocathodes for H2O2 Production Enabled via Outer-Sphere Electron Transfer. / Jung, Onyu; Pegis, Michael L.; Wang, Zixuan; Banerjee, Gourab; Nemes, Coleen T.; Hoffeditz, William L.; Hupp, Joseph T; Schmuttenmaer, Charles A.; Brudvig, Gary W; Mayer, James M.

In: Journal of the American Chemical Society, Vol. 140, No. 11, 21.03.2018, p. 4079-4084.

Research output: Contribution to journalArticle

Jung, O, Pegis, ML, Wang, Z, Banerjee, G, Nemes, CT, Hoffeditz, WL, Hupp, JT, Schmuttenmaer, CA, Brudvig, GW & Mayer, JM 2018, 'Highly Active NiO Photocathodes for H2O2 Production Enabled via Outer-Sphere Electron Transfer', Journal of the American Chemical Society, vol. 140, no. 11, pp. 4079-4084. https://doi.org/10.1021/jacs.8b00015
Jung, Onyu ; Pegis, Michael L. ; Wang, Zixuan ; Banerjee, Gourab ; Nemes, Coleen T. ; Hoffeditz, William L. ; Hupp, Joseph T ; Schmuttenmaer, Charles A. ; Brudvig, Gary W ; Mayer, James M. / Highly Active NiO Photocathodes for H2O2 Production Enabled via Outer-Sphere Electron Transfer. In: Journal of the American Chemical Society. 2018 ; Vol. 140, No. 11. pp. 4079-4084.
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