Thermal N 2 oxidation rates and thus NO yields are negligibly small at the conditions of In the plasma-catalytic experiment of Fig. , the thin Pt film was placed at the center of the heating mantle. The plasma-generated species can react homogeneously in the space ahead of the catalyst bed, over the bed itself, and potentially even post-catalyst. To better represent the experimental configuration and to rationalize the dependence of integral NO yield on the gas composition, we construct a series of pre-catalyst plasma reactor, plasmacatalytic reactor, and post-catalyst reactor (Fig. ). The first reactor is fed with N 2 -O 2 gases at P N = 2 × 10 -3 P N2 and T vib = 6000 K, measured in radio frequency plasmas at conditions similar to Fig. . We predict NO yields across a wider gas composition range than the experiments in Fig. . is shown in Supplementary Fig. ). As a result, the catalyst is ineffective in promoting (or inhibiting) NO production, as observed in the experiments. These results illustrate how optimal catalyst characteristics are a function of reaction conditions.