Adsorption of formaldehyde on nickel oxide studied by thermal programmed desorption and high-resolution electron energy loss spectroscopy

Abstract

Formaldehyde adsorption on NiO(100) ultrathin films grown on a Mo(100) surface has been studied using combined thermal desorption and high-resolution electron energy loss spectroscopies (HREELS). The results show that formaldehyde adsorbs molecularly on NiO(100) film at 90 K and that concurrent polymerization of formaldehyde occurs extensively in the 90-270 K temperature range. Monomeric formaldehyde is chemisorbed onto Ni cationic sites in the oxygen end-on [eta][sup 1](O) orientation, leading to a shift of the v(CO) feature to 1650 cm[sup [minus]1]. Between 250 and 300 K, an n[sup 2](C,O) form of adsorbed formaldehyde is indicated by a v(CO) loss feature at 1320 cm[sup 1] in the HREEL spectrum. All formaldehyde species desorbed below 350 K without decomposition. 58 refs., 5 figs., 2 tabs.