文摘
Chemical changes on methanol/TiO2(110) interface after UV illumination have been investigated by two-photon photoemission spectroscopy (2PPE) and scanning tunneling microscope (STM). Spontaneous recombination of the photocatalytic products, i.e., formaldehyde and hydrogen atoms at the bridging oxygen sites, has been observed using 2PPE. In addition, tip induced recombination of formaldehyde and hydrogen atoms has also been imaged using STM, which further shows that recombination can occur only when the photocatalytic dissociation products stay in the original sites. The experimental observation that methanol can only be dissociated under external forces such as UV illumination while the reverse reaction can take place spontaneously at 130 K may provide an important system for the theoretical calculations of the energetics of adsorbates/TiO2(110).