In Situ Observation of the Dehydration of Formate on Ni(110)

The dehydration of formate adsorbed on Ni(110) has been studied by the direct observation of the CO(a) produced on the surface by means of time-resolved infrared reflection absorption spectroscopy (TR-IRAS). By the quantitative analysis of the temperature-programmed desorption and TR-IRAS results, it was found that the dehydration proceeds simultaneously with the dehydrogenation. The primary kinetic isotope effect ( k H / k D ) using HCOO(a) and DCOO(a) was observed not only in the dehydrogenation but also in the dehydration ( k H / k D = 3.3 at 300 K). This result suggests that the rate-determining step (RDS) is the C−H bond dissociation in both processes. These suggestions let us propose a possible mechanism of the dehydration of formate on Ni(110); the RDS of the dehydration is the C−H bond dissociation which is the same as that of the dehydrogenation, and the produced CO 2 (a) is the precursor of the production of CO(a) and O(a).