An STM, TPD and XPS investigation of formic acid adsorption on the oxygen-precovered c(6x2) surface of Cu(110)

X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption (TPD) and scanning tunnelling microscopy (STM) have been employed to investigate the adsorption of formic acid on O-c(6 x 2)/Cu(110) at 300 K. Formic acid adsorption results in the production of adsorbed formate. TPD profiles indicate that the formate decomposes predominantly via dehydrogenation, with two peak maxima being observed at 415 and 460 K. Following complete decomposition of the formate, approximately one-third of the oxygen in the original O-c(6 x 2) overlayer remained adsorbed in the (2 x 1) and c(6 x 2) structures. A number of adsorbate-related structures were observed with STM upon formic acid adsorption and subsequent annealing. These included (3 x 1) and a structure containing bands of similar to 15 Angstrom width aligned in the [001] direction. After saturation exposures of formic acid the overlayer arrangement is complex, probably containing a formate bilayer with formate adsorbed on top of formate bound directly to the Cu(110) substrate and adsorbed formate on other areas of reconstructed O-c(6 x 2). (C) 1998 Elsevier Science B.V. All rights reserved.