Catalytic activity of electron donation owing to strong interaction between of Pt clusters and Si substrate and its size dependence: analysis on basis of bistability in chemical reaction kinetics

Abstract

Monatomic-layered Pt clusters strongly interacting with a Si substrate have different turnover rates of CO oxidation in heating and cooling processes even at the same temperature and partial pressures of CO and O₂; bistability. Temperature-programed desorption measurements show the adsorption energy of CO of this system is lower than that of bulk Pt surfaces. On the basis of these experimental results, it is evidenced that (1) this system possesses higher activity of dissociative adsorption of O₂ owing to electron-donating catalysis and (2) Pt₃₀ maintains the dissociative-adsorption activity at lower temperature than Pt₂₀.