Under the right conditions, the iridium catalyst helps hydrogen react with CO2. The research team figured out the atomic structure of the catalyst to see exactly how it promotes this reaction. It worked extremely well, they say — they converted a 1:1 mixture of dihydrogen (the form you would want to use in a hydrogen fuel cell) and CO2 to formate, a form of formic acid, at room temperature. Then they increased the pH of the solution, and were able to regenerate the H2 at high pressure. There were no unwanted byproducts like carbon monoxide, the researchers say.