Surface chemistry of acetic acid on clean and oxygen-covered Pd(100)

The surface chemistry of acetic acid is studied on clean Pd(1 0 0), Pd(1 0 0)-p(2 x 2)-O and Pd(1 0 0)-c(2 x 2)-O surfaces in ultrahigh vacuum using a combination of temperature-programmed desorption and X-ray photoelectron spectroscopy. The chemistry on clean Pd(1 0 0) is similar to that on other palladium surfaces, where molecular acetic acid desorbs at similar to 200 K and acetate species form at higher temperatures and decompose at similar to 300 K. In contrast, acetate species predominantly form on the oxygen-covered surfaces and are stable to similar to 380 K on Pd(1 0 0)-p(2 x 2)-O and similar to 375 K on Pd(1 0 0)-c(2 x 2)-O. Acetic acid and its decomposition products, hydrogen, water, carbon monoxide and carbon dioxide form simultaneously at these temperatures. (C) 2007 Elsevier B.V. All rights reserved.