Reducing CO2 to HCO2- at Mild Potentials: Lessons from Formate Dehydrogenase

16 July 2020, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


The catalytic reduction of CO2 to HCO2- requires a formal transfer of a hydride (two electrons, one proton). Synthetic approaches for inorganic molecular catalysts have exclusively relied on classic metal hydrides, where the proton and electrons originate from the metal (via heterolytic cleavage of an M-H bond). An analysis of the scaling relationships that exist in classic metal hydrides reveal that hydride donors sufficiently hydridic to perform CO2 reduction are only accessible at very reducing electrochemical potentials, which is consistent with known synthetic electrocatalysts. By comparison, the formate dehydrogenase enzymes operate at relatively mild potentials. In contrast to reported synthetic catalysts, none of the major mechanistic proposals for hydride transfer in formate dehydrogenase proceed through a classic metal hydride. Instead, they invoke formal hydride transfer from an orthogonal or bi-directional mechanism, where the proton and electron are not co-located. We discuss the thermodynamic advantages of this approach for favoring CO2 reduction at mild potentials, along with guidelines for replicating this strategy in synthetic systems.


formate dehydrogenases
CO2 reduction
metal hydride
orthogonal hydride donor

Supplementary materials

FDH SI July2


Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.