Thomas Meyer came upon the solution almost by accident. Meyer, a chemist at University of North Carolina at Chapel Hill and director of its Energy Frontier Research Center in Solar Fuels, noticed that two separate groups of researchers working on two separate parts of the photosynthetic reaction happened to be using the same class of catalyst—ones with an atom of the metal ruthenium surrounded by organic molecules.
One group used this type of catalyst to split water into hydrogen and oxygen; the other one was splitting carbon dioxide into carbon monoxide and oxygen. “Finding a single catalyst that does both was a big surprise,” Meyer says.
By combining the two steps and using the same catalyst, Meyer realized that they could reproduce photosynthesis in its entirety.
Whereas natural photosynthesis, after multiple reactions, converts water, carbon dioxide and sunlight into oxygen and energy-rich fuels such as sugar, Meyer’s version converts water and carbon dioxide into oxygen, hydrogen and carbon monoxide—and the latter can be combined with hydrogen to eventually make a fuel such as methanol.
These findings suggest that it may be feasible to take carbon emitted from, say, a coal plant and use it to make a liquid fuel such as methanol that replaces or supplements fossil fuels for transportation or electricity generation.
How would it work? Carbon dioxide-laden water from a fossil-fuel plant would pass across ruthenium catalyst membranes, which would trigger artificial photosynthesis, breaking it down into oxygen as well as constituents that can be converted to fuel. Electrical energy to drive the catalytic reaction would come from solar-power cells—although eventually researchers might be able to modify the catalyst to absorb sunlight directly. “That really would make it like photosynthesis,” Meyer says.