Following Electroenzymatic Hydrogen Production by Rotating Ring-Disk Electrochemistry and Mass Spectrometry*.

Gas-processing metalloenzymes are of interest to future bio- and bioinspired technologies. Of particular importance are hydrogenases and nitrogenases, which both produce molecular hydrogen (H2 ) from proton (H+ ) reduction. Herein, we report on the use of rotating ring-disk electrochemistry (RRDE) and mass spectrometry (MS) to follow the production of H2 and isotopes produced from deuteron (D+ ) reduction (HD and D2 ) using the [FeFe]-hydrogenase from Clostridium pasteurianum, a model hydrogen-evolving metalloenzyme. This facilitates enzymology studies independent of non-innocent chemical reductants. We anticipate that these approaches will be of value in resolving the catalytic mechanisms of H2 -producing metalloenzymes and the design of bioinspired catalysts for H2 production and N2 fixation.