Researchers at the University of Wisconsin-Madison found out thatusing inexpensive, oxide -based materials to split water into hydrogen and oxygen gases via solar energy results in the highest reportedsolar-to-hydrogen conversion efficiency of 1.7 percent.
Currently, the sun-capturing semiconductors and catalysts neededin solar fuel production available in the market are expensive. The discovery ofaffordable and oxide based materials would be a great alternative.
"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," a chemistry professor of the University of Wisconsin-Madison, Kyoung-Shin Choi, said in a press release.
Along with postdoctoral researcher Tae Woo Kim, Choi created solar cells from bismuth vanadate using the process called "electrodeposition". The process was doneto increase the compound's surface area to 32 square meters for each gram. Electrodeposition is the same process used to make 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," Choi said.
"More surface area means more contact area with water and, therefore, more efficient water splitting", he added.
To speed up the reaction, Choi and Kim used cheap and flawed catalysts iron oxide and nickel oxide on the bismuth vanadate to exploit their relative strengths.However, Choi said very few researchers give attention to this semiconductor-catalyst junction.
"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," Choi said. He also explained that the iron oxide used in the process unites smoothly with the bismuth vanadate, while the nickel oxide serves a good catalyst when introduced into the water.
Choi and Kim proved in the dual-layer catalyst design that semiconductor-catalyst junction and the catalyst-water junction is truly possible and effective in solar fuel production. Choi expects that these discoveries will enable laboratories around the world to step further in making scientific discoveries.
This research was published on the Feb.13 issue of Science
