Visible Light-Driven Electron Transfer from a Dye-Sensitized p-Type NiO Photocathode to a Molecular Catalyst in Solution: Toward NiO-Based Photoelectrochemical Devices for Solar Hydrogen Production.

The photoelectrochem. activity of a mesoporous NiO electrode sensitized by a Ru complex was studied with several Rh and Co H2-evolving catalysts. Photocurrent ≤80 $μ$A cm-2 was produced by irradn. of such photocathode in the presence of the Rh(III) polypyridyl complexes, while Co complexes gave almost no photocurrent. Photolysis expts. led to the 2-electron reduced form of the Rh(III) complexes into Rh(I) complexes and demonstrate the occurrence of an electron transfer chain from NiO to the catalyst. Mott-Schottky expts. evidenced the pH dependence of the NiO flat band potential, explaining the dramatic drop of the photocurrent in acidic conditions (cyanoanilinium). By contrast, in weaker acid conditions (formic acid) the photocurrent increases and the key Rh(III) hydride intermediate was efficiently generated. In MeCN soln., Rh(III)-H slowly reacts with HCOOH to generate H2. However, this process was not catalytic, because the redn. potential of the Ru sensitizer is not sufficiently neg. to reduce the Rh(III)-H into Rh(II)-H. [on SciFinder(R)]

Références

Titre
Visible Light-Driven Electron Transfer from a Dye-Sensitized p-Type NiO Photocathode to a Molecular Catalyst in Solution: Toward NiO-Based Photoelectrochemical Devices for Solar Hydrogen Production.
Type de publication
Article de revue
Année de publication
2015
Revue
J. Phys. Chem. C
Volume
119
Pagination
5806–5818
ISSN
1932-7447
Soumis le 12 avril 2018