Enhancement of catalytic promotion action of Li on Ru by atomic steps – Comparison of CO dissociation on Ru(1 0 9) and Ru(0 0 1)

The Li-promoted CO dissociation on flat and atomically stepped Ru surfaces has been investigated by thermal desorption spectroscopy (TDS) and infrared reflection–absorption spectroscopy (IRAS). Li-induced dissociation of CO is observed to be greatly enhanced on stepped Ru(1 0 9) compared to Ru(0 0 1) from the scrambling of isotopic CO molecules as well as from the intensity reduction of the CO stretching mode. Interestingly, on Ru(0 0 1), Li produces a highly red-shifted CO stretching mode at ∼1820 cm−1, implying the formation of LixCOy complexes. On the other hand, the preferential adsorption of Li by the atomic steps on Ru(1 0 9) impedes the formation of such complexes.