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Thu04242014

Technology

Sunlight, water and rust produce low-cost hydrogen

The École Polytechnique Fédérale de Lausanne in Switzerland is developing a technology for making hydrogen that has as its ingredients water, rust – and sunlight.

The EPFL researchers’ technology uses inexpensive materials water and metal oxides such as iron oxide or rust in solar hydrogen production.

The device, which is still in the experimental stage, builds on research conducted in the 1990’s at EPFL by Michaël Grätzel. Mr. Grätzel invented a photoelectrochemical tandem solar cell – basically a dye-sensitized solar cell partnered with an oxide-based semiconductor – which could produce hydrogen directly from water.

Kevin Sivula and his colleagues worked on the latest version of this technology, focusing on resolving the main outstanding problem with PEC – its cost.

“A U.S. team managed to attain an impressive efficiency of 12.4 percent,” noted Mr. Sivula. “The system is very interesting from a theoretical perspective, but with their method it would cost 10,000 dollars to produce a 10-square centimeter surface.”

Key to the inexpensiveness of the latest PEC is the semiconductor which triggers the water-splitting reaction in the hydrogen production process. Iron oxide or rust is a stable and abundant material.

The team improved its semiconductor properties with nanotechnology.

The iron oxide used in the PEC is nanostructured, enhanced with silicon oxide and covered with a nanometer-thin layer of aluminum oxide and cobalt oxide. This improves the electrochemical properties of the material while still being cost-effective and easy to produce.

While the efficiency is still low – between 1.4 percent and 3.6 percent – Mr. Sivula believes they will eventually be able to attain an efficiency of 16 percent.

The main draw of this technology, though, would be its low cost.

“With our less expensive concept based on iron oxide, we hope to be able to attain efficiencies of 10% in a few years, for less than $80 per square meter. At that price, we’ll be competitive with traditional methods of hydrogen production,” concluded Mr. Sivula. – EcoSeed Staff



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