Second/Additional Bistability in a CO Oxidation Reaction on Pt(111): An Extension and Compilation

Abstract

The CO oxidation reaction on Pt(111) was investigated in a pressure range of reactants 10–7–10–5 mbar and a temperature range 364–643 K. In the studied dependence of reaction rate vs temperature, two loops of hysteresis were found in reaction rate measurements instead of one, as expected. The explanation for the observed phenomena leads to two regions of bistability in the kinetic phase diagram caused by two phase transitions. These two detected phase transitions were confirmed independently by variation of two external control parameters, temperature and CO partial pressure, respectively. It means that the two kinetic phase diagrams were crossed in two parameter spaces, i.e., by variation of temperature with constant partial pressure of reactants and by variation of the CO partial pressure in isothermal conditions. The presented experimental data and comparison with literature data suggest that both phase transitions were observed previously but interpreted erroneously as one phenomenon. A unifying expla...