VATIS UPDATE Article

Scientists at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) have developed a method which boosts the longevity of high-efficiency photocathodes in photoelectrochemical water-splitting devices. Using a photoelectrochemical (PEC) device is a promising way to produce hydrogen. A PEC cell absorbs sunlight and converts that energy into hydrogen and oxygen by splitting water molecules.

Unfortunately, high efficiency devices developed to date quickly degrade in the acidic solution to which the cell is exposed. The challenge of making a more durable cell must be overcome before renewable hydrogen from PEC devices can become commercially viable. The concept of using an integrated tandem cell based on the NREL high-efficiency tandem solar cell to split water and produce hydrogen was developed 18 years ago by John Turner, who has been with the laboratory since 1979.

Turner designed a tandem solar cell containing layers of gallium indium phosphide (GaInP2) and gallium arsenide (GaAs) semiconductors to absorb the sunlight and produce the power necessary for the photoelectrochemical water-splitting reaction. This describes how NREL researchers determined that greater photocathode stability and high catalytic activity can be achieved by depositing and annealing a bilayer of amorphous titanium dioxide (TiOx) and molybdenum sulfide (MoSx) onto GaInP2.
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