IRAS and TPD study of adsorbed formic acid on Pt(110)-(1x2) surface

The adsorption of formic acid on the Pt(110)-(1x2) surface was studied by infrared reflection absorption spectroscopy (IRAS) and temperature-programmed desorption (TPD). Formic acid dissociatively adsorbed to form bridging formate at low exposure and 140 K, giving IRAS peak at 2935, 1338 and 1321 cm(-1) assigned to the C-H stretching, C-H in-plane bending, and O-C-O symmetric stretching modes, respectively. On increasing the exposure, formic acid adsorbed on the formate-covered surface as a multilayer. Molecular adsorption of formic acid on the formate-covered surface reduced the intensities of the C-H stretching and C-H in-plane bending bands of formate. The adsorption temperature was an important factor for the crystalline structure of the multilayer of formic acid. Molecular adsorption of formic acid al 143 K produced structure of the a-form, while adsorption at lower temperature resulted in an amorphous phase.