… “The researchers designed and built a two-foot-tall prototype reactor that has a quartz window and a cavity that absorbs concentrated sunlight.
The concentrator works like the magnifying glass you used as a kid to focus the sun's rays, says Haile.
At the heart of the reactor is a cylindrical lining of ceria.
Ceria—a metal oxide that is commonly embedded in the walls of self-cleaning ovens …” …
Via Cal Tech: Solar Reaction Press Release.