A new method of harvesting the Sun's energy is emerging, thanks to scientists at UC Santa Barbara's Departments of Chemistry, Chemical Engineering, and Materials. Though still in its infancy, the research promises to convert sunlight into energy using a process based on metals that are more robust than many of the semiconductors used in conventional methods.
The technology does not use semiconductor materials to provide the electrons and venue for the conversion of solar energy, but nanostructured metals –– a "forest" of gold nanorods.
For this experiment, gold nanorods were capped with a layer of crystalline titanium dioxide decorated with platinum nanoparticles, and set in water. A cobalt-based oxidation catalyst was deposited on the lower portion of the array.
As the "hot" electrons in these plasmonic waves are excited by light particles, some travel up the nanorod, through a filter layer of crystalline titanium dioxide, and are captured by platinum particles. A reaction then 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.
According to the study, hydrogen production was clearly observable after about two hours.