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A touch of purple for better hydrogen production

A touch of purple for better hydrogen production
The color of salt lakes is caused by microorganisms. Photo from Argonne National Laboratory

The visibly purplish tinge of the salt flats of California and Nevada are caused by microorganisms known as archaea. These microorganisms contain a protein called bacteriorhodopsin which scientists at the United States Department of Energy’s Argonne National Laboratory have used to develop an efficient photocatalyst for hydrogen production.

Bacteriorhodopsin have the ability to act as proton pumps, they capture light energy and use it to move protons across the cell membrane from inside the cell to outside.

The researchers combined bacteriorhodopsin with semiconducting nanoparticles of a semiconductor material known as titanium dioxide.

Titanium dioxide exposed to ultraviolet light can cause a reaction that splits water molecules. By making modifications on the basic chemistry of the material, the scientists hoped to enable titanium dioxide to react with other parts of the visible light spectrum.

“Titanium dioxide alone reacts with ultraviolet light, but not with visible light, so we used biological photoreactive molecules as a building block to create a hybrid system that could use visible light efficiently,” said Argonne nanoscientist Elena Rozhkova.

The Argonne scientists used the bacteriorhodopsin to provide protons which can be combined with free electrons at small platinum sites interspersed in a titanium dioxide matrix. Thus, when exposed to visible light, the water splitting action is triggered producing hydrogen.

According to the scientists, this bio-assisted hybrid photocatalyst outperforms many other similar systems for hydrogen generation and could pave the way for commercial use of hydrogen powered devices.

The work was performed at Argonne’s Center for Nanoscale Materials, which is supported by the U.S. Department of Energy’s Office of Science. – EcoSeed Staff

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