Catalysis at single-crystal Pt(110) surfaces: Global coupling and standing waves

Recently various types of spatiotemporal concentration patterns have been observed in experimental studies of catalysis on single-crystal surfaces. One of the most interesting phenomena among these is the standing-wave pattern which has been seen in CO+${\mathrm{O}}_2$→${\mathrm{CO}}_2$ on Pt(110). A kinetic model involving surface reconstruction has been proposed for this system by Eiswirth, Krischer, and Ertl [Appl. Phys. A 51, 79 (1990)]. Here, we add spatial-coupling terms due both to CO diffusion and to global gas-phase fluctuations and we study the possible wave patterns in this set of reaction-diffusion equations. We argue that the standing waves may be due to a self-induced parametric driving mechanism. Our analytical results as well as our numerical simulations are qualitatively consistent with the experimental findings.