Reverse water–gas shift reaction catalyzed by diatomic rhodium anions

We experimentally identify the gas-phase species Rh 2 − that can drive the reverse water–gas shift (RWGS, CO 2 + H 2 → CO + H 2 O) reaction. The generation of a gas-phase H 2 O molecule and [Rh 2 (CO) ads ] − at room temperature was identified and the only elementary step that requires extra energy to complete the catalysis is CO desorption.