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A cheaper and more efficient solar-hydrogen system

A new photocatalyst splits water while avoiding the use of any precious metals …

As scientists continue to pursue alternative fuels that may enable us to break free of the fossil variety, a group of researchers has taken another step towards directly converting solar energy into fuel, in this case, hydrogen. A new system that converts light and water into hydrogen is less expensive than many others, and the photoelectrochemical platform it uses is more reactive, efficient, and has a much longer lifetime.

The device consists of indium phosphide crystals that act as quantum dots, harvesting light that's transferred to an iron-sulfur electrocalayst. That catalyst triggers reactions in an aqueous electrolyte solution, producing hydrogen. The iron-sulfur catalyst works best in the dark, but is able to extract the light that normally emanates from the luminescent crystals by pulling it out for use in converting the electrolyte to fuel.

Once combined and submerged in the electrolyte solution, a bias potential across the system allows it to separate hydrogen from oxygen. The assemby is able to sustain the reaction under the same potential for at least an hour at a time, and creates dihydrogen molecules at an efficiency of about 60 percent, a breakthrough for fuel systems of this kind.

While the indium phosphide and iron-sulfur are relatively abundant and inexpensive, the setup built the indium phosphide crystals on a gold cathode, and used a platinum anode to complete the circuit. While these materials could certainly be swapped out for others, it would probably result in a diminished efficiency. For this system to be viable in large-scale production, that's a change that might be worth serious consideration.

(This paper was published in February, but brought to our attention by a regular reader.)

Angewandte Chemie, 2010. DOI: 10.1002/anie.200906262  (About DOIs).

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Channel Ars Technica