RESEARCH
March 9, 2009

Coated nano mesh gets more out of light

Coat a net-like nanostructure made of one titanium semiconductor with a second titanium semiconductor and you can boost the amount of light the structure converts to electricity, and possibly the amount of hydrogen it extracts from water.

A nanoscale mesh of titanium disilicide coated with titanium dioxide generates about 39 percent more electricity from ultraviolet light than titanium dioxide alone. The coated structure has a peak efficiency of 16.7 percent compared to 12 percent for titanium dioxide.

Titanium dioxide is a good catalyst for splitting water into hydrogen and oxygen, but it doesn't conduct electricity well. Titanium disilicide is a better conductor. Combining the materials results in more electrons harvested from the same number of absorbed photons. The energy drives the chemical reaction that splits the water molecules.

Neither titanium semiconductor absorbs visible light, however. This limits the amount of energy the materials can generate from sunlight. Ultraviolet makes up only about 4 percent of sunlight. Adding tungsten boosts the nanostructure's visible light conversion efficiency to 0.83 percent.

Research paper:
TiO2/TiSi2 Heterostructures for High-Efficiency Photoelectrochemical H2O Splitting
Journal of the American Chemical Society, published online February 11, 2009

Researchers' homepage:
Wang Lab

Related stories and briefs:
Nano mesh conducts better -- previous development


Back to ERN March 9, 2009

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