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 language | English |
|---|---|
| Pages (from-to) | 4079-4084 |
| Number of pages | 6 |
| Journal | Journal of the American Chemical Society |
| Volume | 140 |
| Issue number | 11 |
| DOIs | |
| Publication status | Published - Mar 21 2018 |
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ASJC Scopus subject areas
- Catalysis
- Chemistry(all)
- Biochemistry
- Colloid and Surface Chemistry
Cite this
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 journal › Article
}
TY - JOUR
T1 - Highly Active NiO Photocathodes for H2O2 Production Enabled via Outer-Sphere Electron Transfer
AU - Jung, Onyu
AU - Pegis, Michael L.
AU - Wang, Zixuan
AU - Banerjee, Gourab
AU - Nemes, Coleen T.
AU - Hoffeditz, William L.
AU - Hupp, Joseph T
AU - Schmuttenmaer, Charles A.
AU - Brudvig, Gary W
AU - Mayer, James M.
PY - 2018/3/21
Y1 - 2018/3/21
N2 - 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.
AB - 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.
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UR - http://www.scopus.com/inward/citedby.url?scp=85044195129&partnerID=8YFLogxK
U2 - 10.1021/jacs.8b00015
DO - 10.1021/jacs.8b00015
M3 - Article
AN - SCOPUS:85044195129
VL - 140
SP - 4079
EP - 4084
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 11
ER -