Standing fronts in oscillatory reactions on composite catalytic surfaces

We present Monte Carlo simulations of a standing reaction front formed during NO reduction by H2 on a catalyst consisting of two metal strips. One strip (to the right) is considered to be catalytically active. Specifically, the reaction is assumed to occur on Pt(1 0 0). The other strip (to the left) is catalytically inactive but can adsorb NO. The processes on the two strips are coupled via NO diffusion over their boundary. Kinetic oscillations result from NO-induced restructuring of the Pt(1 0 0) surface. The reaction fronts obtained for this model are quite unusual. For example, the NO coverage may be low on the left sublattice, high in a narrow zone on the right sublattice near the metal–metal boundary, and then again relatively low. These findings illustrate richness of spatio-temporal patterns which can be observed in heterogeneous catalytic reactions on the mesoscopic scale.