Adsorbate-induced lifting of substrate relaxation is a general mechanism governing titania surface chemistry

• Published in: Nature communications 2016-09, Vol.7 (1), p.12888-12888, Article 12888
• Main Authors: Silber, David, Kowalski, Piotr M., Traeger, Franziska, Buchholz, Maria, Bebensee, Fabian, Meyer, Bernd, Wöll, Christof
• Format: Article
• Language: English
• Subjects: 119/118; 140/146; 639/301/119/544; 639/638/440/527/2257; 639/638/542; Adsorption; Catalysis; Humanities and Social Sciences; multidisciplinary; Photochemistry; Science; Science (multidisciplinary); Surface chemistry
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms12888

Under ambient conditions, almost all metals are coated by an oxide. These coatings, the result of a chemical reaction, are not passive. Many of them bind, activate and modify adsorbed molecules, processes that are exploited, for example, in heterogeneous catalysis and photochemistry. Here we report an effect of general importance that governs the bonding, structure formation and dissociation of molecules on oxidic substrates. For a specific example, methanol adsorbed on the rutile TiO 2 (110) single crystal surface, we demonstrate by using a combination of experimental and theoretical techniques that strongly bonding adsorbates can lift surface relaxations beyond their adsorption site, which leads to a significant substrate-mediated interaction between adsorbates. The result is a complex superstructure consisting of pairs of methanol molecules and unoccupied adsorption sites. Infrared spectroscopy reveals that the paired methanol molecules remain intact and do not deprotonate on the defect-free terraces of the rutile TiO 2 (110) surface. Molecules on a metal surface may be modified by the presence of oxide layers, but further mechanistic understanding is still required. Here the authors show for methanol on rutile TiO 2 (110) that strongly bonded adsorbates lift surface relaxations, leading to substrate-mediated interaction between adsorbates.