Adsorption of methanol on oxygen-modified ZrC(100) and (111) surfaces

Adsorption of methanol on clean and oxygen-modified ZrC(100) and (111) surf aces at room temperature has been studied by ultraviolet photoemission spec troscopy (UPS). It is determined that methanol adsorbs molecularly on the ( 100) surface while it dissociates on the (111) surface; methoxy species and completely dissociated atomic species are coexistent on the (111) surface. As the (100) surface is precovered with oxygen (less than or equal to 20 L ), methanol is dissociated on the surface to form methoxy species and the s ticking probability in the initial stage is enhanced, indicating that the p readsorbed oxygen acts to facilitate dissociative adsorption. On the other hand, the preadsorbed oxygen is found to inhibit methanol adsorption due to site blocking on the (111) surface.