The catalyst is the key to splitting water into oxygen and hydrogen. Much recent research has focused on titanium dioxide catalysts, and last year researchers found that nanotubes made of titanium dioxide are more effective than bulk titanium dioxide. The catch is pure titanium dioxide only works with ultraviolet light, which makes up only a small portion of sunlight. (See Nanotubes crank out hydrogen, TRN, February 9/16, 2005)
Researchers from the University of Texas at Austin have found a way to add carbon to the titanium dioxide nanotubes in order to shift their catalytic activity from ultraviolet to visible light. They also found that the length of the nanotubes plays a key role; 3.3 microns is optimum.
The carbon-infused titanium dioxide nanotubes generated more hydrogen from sunlight than pure titanium dioxide nanotubes.