To describe plasma-catalytic NO oxidation yields over the porous Pt catalyst (Fig. ), we treat this region as a sum of coupled contributions of a non-catalytic bulk-phase, described using the same Zeldovich parameters, and a surface-catalytic phase, described using the Pt step parameters. The relative contributions of these two phases is a function of the reactor volume and number of active sites (Supplementary equation ( )). The total volume is taken to be that of the porous Pt catalyst bed, and flow rate and free volume-to-active site ratios are taken to be consistent with the experimental setup.