One Model, Two Enzymes ‐ Activation of H2 and CO

The ability to catalyze the oxidation of both H2 and CO in the same pot would be a major boon to hydrogen technology since CO is a consistent contaminant of H2 supplies. Here, we report just such a catalyst, with the ability to catalyze the oxidation of either or both H2 and CO, based on pH. This catalyst is based on a NiIr core that can mimic the chemical function of [NiFe]hydrogenase in acidic media (pH 4‐7) and carbon monoxide dehydrogenase in basic media (pH 7‐10). We have applied this catalyst in a demonstration fuel cell using H2, CO, and H2/CO (1/1) feeds as fuels for oxidation in the anode. The fuel cell's power density depends upon the pH in the media of the fuel cell and shows a similar pH dependence in‐flask. We have isolated and characterized all intermediates in our proposed catalytic cycles.