A research team has invented a “wormlike” hematite photoanode which can convert sunlight and water to clean hydrogen energy with a record-breaking high efficiency of 5.3 percent.
The previous record of solar hydrogen efficiency among stable oxide semiconductor photoanodes was 4.2 percent owned by the research group of Prof. Michael Graetzel at the Ecole Polytechnique de Lausanne (EPFL), Switzerland.
The key to the solar water splitting technology is the semiconductor photocatalysts that absorb sunlight and split water to hydrogen and oxygen using the absorbed solar energy.
Hematite, an iron oxide (the rust of iron, Fe2O3) absorbs an ample amount of sunlight. It has also excellent stability in water, a low price, and environmentally benign characteristics.
Prof. Jae Sung Lee of UNIST led the joint research with Prof. Kazunari Domen’s group at the University of Tokyo, Japan, developing new anode material which has outstanding hydrogen production efficiency.
Prof. Lee and coworkers employed a series of modifications to improve the property of hematite. First, a unique single-crystalline “wormlike” morphology was produced by using a nanomaterial synthesis technique. Second, a small amount of platinum was introduced into the hematite lattice as doping.
Finally, a cobalt catalyst was employed to help oxygen evolution reaction. These modifications reduced energy loss due to charge recombination and brought the record-breaking solar-to-hydrogen conversion efficiency.
This research has been published in Scientific Reports. (ANI)