The material mimics plants by absorbing sunlight and using that light to convert water into hydrogen and oxygen in a process called oxidation. The hydrogen can then be used for energy generation, and the oxygen can be recirculated back into the atmosphere. No carbon dioxide is produced during the conversion, making the process environmentally friendly. This process is very similar to plant photosynthesis, which uses sunlight to convert water and carbon dioxide into oxygen and glucose which provides the plant with an abundant energy source.
Mendoza-Cortes was working with a multi-layer form of manganese oxide known as birnessite when he made his breakthrough discovery. He was looking for a material that trapped sunlight, did not rust in the presence of water and was inexpensive to manufacture. Originally, Mendoza-Cortes worked with the multi-layer form of manganese oxide, but soon he began peeling back the layers until a single layer remained. He was pleasantly surprised to discover that the single layer material trapped light at a much faster rate than the multi-layered form.
The single-layer birnessite has an advantage over current solar cells, which are stacked to form layers approximately hundreds of micrometers in thickness. “It is cheap, it is efficient and you do not need a large amount to capture enough sunlight to carry out fuel generation,” said Mendoza-Cortes when speaking about the manganese oxide material. In theory, the material could be used for household energy generation by installing birnessite panels on a roof and using the sun to turn rain water into a usable source of fuel.
