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Photosynthèse artificielle à base de résonance plasmon

le 23 septembre 2014

Hiroaki Misawa, professeur au Research Institute for Electronic Science, Hokkaido University de Sapporo, Japon, interviendra le 23 septembre à l'ENS Cachan.

Plasmon-enhanced photocurrent generation

Plasmon-enhanced photocurrent generation

Hiroaki Misawa, spécialiste dans le domainede la photochimie, les process laser, les nano/micro sciences et technologies présentera ses recherches sur la "photosynthèse artificielle à base de résonance plasmon".

Plasmon resonance spectrum

We have demonstrated plasmonic photocurrent generation from visible to near-infrared wavelengths without deteriorating photoelectric conversion using electrodes in which goldnanorods are elaborately arrayed on the surface of a TiO2 single crystal.

Water splitting system

We have also reported the stoichiometric evolution of oxygen via water oxidation by irradiating the plasmon-enhanced photocurrent generation system with near-infrared light.
In the present study, we developed a plasmon-assisted water splitting system that operates under irradiation by visible light; the system is based on the use of two sides of the same strontium titanate (SrTiO3) single crystal
substrate.

The water splitting system contains two solution chambers to separate hydrogen (H2) and oxygen (O2), respectively.
To promote water splitting, a chemical bias was applied by pH values regulations of those chambers. The quantity of H2 evolved from the surface of platinum, which was used as a reduction co-catalyst, was twice of O2 evolved from an Au nanostructured surface.

Thus, the stoichiometric evolution of H2 and O2 was clearly demonstrated.
The hydrogen evolution action spectrum closely corresponds to the localized surface plasmon resonance spectrum, indicating that the plasmon-assisted charge separation at the Au/SrTiO3 interface promotes water oxidation and the subsequent reduction of a proton on the backside of the SrTiO3 substrate.

Artificial photosynthesis

We have elucidated furthermore that the chemical bias is dramatically reduced by plasmonic effects, which indicate the possibility of constructing an artificial photosynthesis system with low energy consumption.

According to the analogous method of the water splitting system, we have successfully constructed the artificial-photosynthesis system which produces the ammonia by a photofixation of a nitrogen molecule based on visible light irradiation.

Unlike the water splitting system, ruthenium is used as a co-catalyst instead of a platinum for the ammonia synthesis, and not asolution system but a gas system is used to reduce nitrogen gas.

The action spectrum of the apparent quantum efficiency of ammonia evolution showed good agreement with the plasmon resonance spectrum.
Therefore, we succeeded in photoelectrochemical synthesis of ammonia by the visible light irradiation through the plasmon-induced charge separation.
Type :
Colloques, Séminaires - conférences
Lieu(x) :
Campus de Cachan

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