摘要：

The interaction of formic acid with clean and oxygen-dosed Rh(111) surfaces has been investigated by electron energy loss (in the electronic range), thermal desorption and photoelec-tron spectroscopy. Formic acid adsorbs readily on the Rh(111) surface at 100 K with a high sticking probability. Three adsorbed states have been distinguished: a condensed layer ( T _p=170 K), a chemisorbed layer ( T _p = 202 K) and the formation of formate species. The latter is stable up to 200 K, but decomposes completely at 200–250 K. The major products are: H₂ ( T _p = 323 K) and CO₂ ( T _p = 255–290 K), but H₂O ( T _p = 263 K) and CO ( T _p = 530 K) are also formed. Preadsorbed oxygen exerted a readily observable influence on the interaction of HCOOH with the Rh(111) surface. It increased the extent of dissociation of HCOOH and extended the region of stability of surface formate by at least 80–100 K. This was demonstrated by higher stability of photoemission peaks due to formate and by simultaneous production of CO₂ and H₂O with T _p = 377–385 K at saturation oxygen coverage.

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