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Abstract:
The influence of Ni deposits in the submonolayer range on the activity of a Pt(110) surface in catalytic CO oxidation has been investigated in the 10−5 and 10−4 Torr range by means of reaction rate, LEED, AES and work function measurements. The presence of Ni on the surface led to an overall reduction of the CO2 production rate with the exception of the low temperature regime where an increase in the reaction rate could be observed for T ≦ 470 K. The increase in catalytic activity at low temperature could be traced back to a change in the CO adsorption properties caused by Ni which reduces the inhibitive effect of a CO adlayer on oxygen adsorption. With oxygen a ternary Pt/Ni/O phase could be observed characterized by a c(4 × 2) pattern in LEED. The reactivity of the oxygen in the ternary phase towards CO is at an intermediate level between the high reactivity of chemisorbed oxygen and the low reactivity of an oxide.
