“Golden Sandwich” solar panels, the breakthrough from Hokkaido University that converts 85% of sunlight to produce hydrogen

Scientists of the Hokkaido University  Research Institute for Electronic Science have developed the “Golden Sandwich“, a photoelectrode that can harvest 85% of sunlight to produce hydrogen.

An experimental project that has not yet been commercialized, but, when launched on the market, this technology could revolutionize the entire renewable energy industry.

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Hydrogen can become an important component of the clean and sustainable energy economy of the future, althought most of the hydrogen available today on the market derives from natural gas, which in turn is a product of “fracking“, a very polluting process through which the hydrocarbons are extracted. Hydrogen will never be a totally green energy until its production will depend on the extraction of natural gas and highly polluting processes.

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Professor Hiroaki Misawa, lead author of the study, explained:

“Our photoelectrode successfully created a new condition in which plasmon and visible light trapped in the titanium oxide layer strongly interact, allowing light with a broad range of wavelengths to be absorbed by gold nanoparticles. The light energy conversion efficiency is 11 times higher than those without light-trapping functions”.

The panel structure is at the base of this innovation: it is made of a titanium dioxide film, only 30 nanometers thick, coupled with a 100-nanometer gold film on one side and gold nano-particles on the other. When sunlight hits the side of the nanoparticles, the gold film underneath acts like a mirror trapping the light in the cavity between the two layers of gold. This layered structure helps the nanoparticles absorbing more available light, this is essential for having a surprisingly high energy conversion factor.

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The “mirror” effect from gold

In the study published on Nature Nanotechnology the research team claims that gold nanoparticles are known to exhibit a phenomenon called “localized plasmon resonance“, that enhance light absorption.

Researchers have concluded their report saying:

“”Using very small amounts of material, this photoelectrode enables efficient conversion of sunlight into renewable energy, further contributing to a sustainable society.”

 

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