Interaction of iron with a wagon wheel-like ultrathin TiO_x film grown on Pt(111)

Abstract

The structure and thermal evolution of Fe nanoparticles deposited on a wetting TiOx ultrathin film epitaxially grown on Pt(111) has been characterized by various surface science techniques. Combining the results obtained it is shown that, at room temperature, metallic Fe nucleates randomly and oxidizes at the interface. A thermal treatment causes Fe migration through the TiOx layer, forming a mixed oxide and a new hexagonal ultrathin film phase. Finally, the pristine TiOx phase motif is restored, due to the complete diffusion of Fe into the Pt substrate.

Evidence of the Encapsulation Model for Strong Metal–Support Interaction under Oxidized Conditions: A Case Study on TiOx/Pt(111) for CO Oxidation by in Situ Wide Spectral Range Infrared Reflection Adsorption Spectroscopy

“…The presence of oxide on the metal particles has been confirmed by many surface science studies of metal nanoparticles on single-crystal TiO 2 surfaces − and growing TiO x thin films on metal single-crystal surfaces. − Several ultrathin metal oxides have been found to exhibit unique chemical properties and promising applications in heterogeneous catalysis. ,, Although these oxide layers often suppress the catalytic activities of the metals, , the novel properties of the ultrathin oxides themselves allow new possibilities for the development of chemically active materials. ,, In the past several decades, the changes of catalyst properties caused by SMSI have been reported in large quantities. However, due to complexities of a realistic catalyst, there is still a lack of clear understanding of the origins of the promotion effects.…”

Variation of SMSI with the Au:Pd Ratio of Bimetallic Nanoparticles on TiO2(110)

“…One of the most intriguing aspects of ultrathin oxide layers is the possibility to use them as templates for metal adsorption to form uniform, periodically located metal nanoparticles on the oxide layer. This sort of behavior arises from the presence of more energetically favourable adsorption sites at the inter-corner regions (so-called pico-holes) of the pinwheel TiO x structure, which are not necessarily atomic vacancies in that oxide layer [45–47, 61]. Figure 6a shows an STM image of the pinwheel oxide layer following exposure of 0.1 MLE Au at RT.…”

“…Associated with interest in graphene like 2D materials [ 43 ], there have been a number of studies of 2D oxide nanomaterials [ 31 , 44 , 45 ]. The commonly accepted stacking sequence of TiO x ultrathin oxide layers on transition metals is the following: M–Ti–O x , where M corresponds to the transition metal bonded to the oxide substrate [ 46 , 47 ].…”

Oxid-fém kölcsönhatás és ötvöződési folyamatok vizsgálata Rh(111) és TiO2(110) felületeken pásztázó alagútmikroszkópiával

“…Az korai felületvizsgálatok főként a fémfelületek tanulmányozására vonatkoztak, amelyet később az oxid-és félvezető felületek valamint ultravékony oxidok (UTO -ultra thin oxide) fémekkel alkotott határfelületeinek tanulmányozása 9,10 követtek. Az elmúlt 20 -30 évben az utóbbi terület a felületkémiai kutatások kiemelten fontos tárgyát képezi.…”

“…Kísérleti és elméleti adtatok egyaránt bizonyítják, hogy az UTO rétegek lokális inhomogenitásokat mutatnak az elektronszerkezetükben 116,117,121 . Elegendő a sávelhajlásra gondolnunk a fém/oxid határrétegben és a kilépési munkában történő változásokra fém/oxidréteg rendszerek esetében 122 . Ezek a megfontolások még komplexebbé válnak, amikor egy fémfelületen lévő oxidrétegre ismét fémet választunk le, amely egy újabb fém/oxid határréteget, ill. összességében egy szendvics-szerkezetet hoz létre, amivel töltéstranszfert és polarizációt okozhat.…”