Generating electricity is now not the only idea for converting sunlight into energy. The solar energy can also be used to produce chemical fuels, such as hydrogen that can in turn power cars, trains and trucks.
One of the limitation of using sunlight for producing fuel is related to sun-capturing semiconductors and the catalysts to generate fuel, which are the most efficient materials for producing fuel but too expensive when compared to gasoline.
"In order to make commercially viable devices for solar fuel production, the material and the processing costs should be reduced significantly while achieving a high solar-to-fuel conversion efficiency," said Kyoung-Shin Choi, a chemistry professor at the University of Wisconsin-Madison.
Two researchers, Choi and Tae Woo Kim- post doctoral researcher, combined low-cost, oxide based materials to split water into hydrogen and oxygen gases using solar energy, with a conversion efficiency of 1.7 percent the highest reported for any oxide-based photoelectrode system, according to a study.
Choi created solar cell from a chemical compound, bismuth vanadate using electrodeposition -similar process used in making gold-plated jewelry or surface-coat car bodies.
"Without fancy equipment, high temperature or high pressure, we made a nanoporous semiconductor of very tiny particles that have a high surface area," says Choi, whose work is supported by the National Science Foundation. "More surface area means more contact area with water, and, therefore, more efficient water splitting."
"The problem is, in the end you have to put them together. Even if you have the best semiconductor in the world and the best catalyst in the world, their overall efficiency can be limited by the semiconductor-catalyst interface. Since no one catalyst can make a good interface with both the semiconductor and the water that is our reactant, we choose to split that work into two parts. The iron oxide makes a good junction with bismuth vanadate, and the nickel oxide makes a good catalytic interface with water. So we use them together", Choi added.
"Combining this cheap catalyst duo with our nanoporous high surface area semicoductors electrode resulted in the construction of an inexpensive all oxide-based photoelectrode system with a record high efficiency."
Choi expects the basic work done to prove the efficiency development by nanoporous bismuth vanadate electrode and dual catalyst layers will provide labs around the globe with fodder for leaps forward.
The details of the study have been published in the Science Journal.