Gold nanorods, a titanium dioxide filter and platinum were used by researchers at the University of California, Santa Barbara to split water into hydrogen and oxygen.
The hydrogen fuel cell, in fact, is nothing new, and has been around for nearly one hundred years. The most ideal fuel, hydrogen gas, isn’t freely available in the world around us. Generating hydrogen from water using an electrolytic cell has been around for over two hundred years.
Still, it is a very inefficient process, and if the method to generate the gas uses more energy than can be harvested from the fuel cell, then really, what’s the point? Ff the main reason to use hydrogen is to eliminate carbon dioxide emissions, then hydrogen needs a clean source of energy, like the solar power.
Researchers at the University of California, Santa Barbara, have gone beyond semiconductor solar cells to a metal-based cell that splits water molecules into hydrogen and oxygen directly.
The new plasmonic solar cell works on a similar principle to that of the semiconductor solar cell, but instead of generating an electric current, generates an electronic oscillation, referred to as plasmonic waves. The multilayered nanostructure consists of a cobalt-based catalyst, a forest of gold nanorods, a titanium dioxide filter, and platinum.
“As the ‘hot’ electrons in these plasmonic waves are excited by light particles, some travel up the gold nanorod, through a filter layer of crystalline titanium dioxide, and are captured by platinum particles. This causes the reaction that splits hydrogen ions from the bond that forms water. Meanwhile, the holes left behind by the excited electrons head toward the cobalt-based catalyst on the lower part of the rod to form oxygen,” explains Sonia Fernandez of the University of California.