Theoretical analysis of small Pt particles on rutileTiO2(110)surfaces

Abstract

The adsorption profiles and electronic structures of Pt n ͑n =1-4͒ clusters on stoichiometric, reduced and reconstructed rutile TiO 2 ͑110͒ surfaces were systematically studied using on site d-d Coulomb interaction corrected hybrid density-functional-theory ͑DFT͒ calculations. The atomic structure of small Pt cluster adsorbates mainly depends on the stoichiometry of the corresponding titania support. The cluster shapes on the bulk terminated ideal surface look like their gas phase low-energy structures. However, for instance, they get significantly distorted on the reduced surfaces with increasing oxygen vacancies. On nonstoichiometric surfaces, Pt-Ti coordination becomes dominant in the determination of the adsorption geometries. The electronic structure of Pt n / TiO 2 ͑110͒ systems cannot be correctly described by pure DFT methods, particularly for nonstoichiometric cases due to the inappropriate treatment of the correlation for d electrons. We performed DFT+ U calculations to give a reasonable description of the reconstructed rutile ͑110͒ surface. Pt clusters induce local surface relaxations that influence band edges of titania support and bring a number of band-gap states depending on the cluster size. Significant band gap narrowing occurs upon Pt n -surface interaction due to adsorbate driven states on the bulk terminated and reduced surfaces. On the other hand, they give rise to a band-gap widening associated to partial reoxidation of the reconstructed surface. No metallization arises even for Pt 4 on rutile.

Pt atoms adsorbed onTiO2(110)−(1×1)studied with noncontact atomic force microscopy and first-principles simulations

“…This is in good agreement with the results of previous theoretical studies of the Pt/TiO 2 (110) system [10][11][12]32,33] and also with the results of our calculations, summarized in Table I, where the relative energies and bonding distances for the different sites are given. All the calculations predict that the hollow site [see the structure in Fig.…”

“…3(a) and 3(b)], it establishes chemical bonds with the neighboring Ti 5f atoms. This reflects in the projected density of states of Pt on TiO 2 , as also confirmed by previous theoretical works [12,36]. For the hydroxylated surface, although there is no experimental evidence of such a bond formation upon Pt adsorption, we expect a behavior similar to that described for clean TiO 2 (110).…”

“…The subangstrom spatial resolution achieved in this work, together with density functional theory (DFT) calculations, has revealed the interaction of Pt atoms with a class of surface defects, vacancies of basal threefold coordinated oxygen atoms that are located in the same plane as the Ti atoms, that have not been identified in previous STM studies [9]. This study concludes that the most favorable Pt adsorption site is not on the oxygen vacancy on the top bridging oxygen rows predicted by previous DFT studies [10][11][12], but on these new vacancy sites.…”

A review on plasmonic metal⿿TiO2 composite for generation, trapping, storing and dynamic vectorial transfer of photogenerated electrons across the Schottky junction in a photocatalytic system

“…Further, it is well-known that Ti atoms show 6-fold coordination and oxygen atoms are 3-fold coordination in rutile TiO 2 . The nanowires terminating at (1 1 0) may break the Ti O bonds which lie normal to the surface plane and results in 5-fold coordination for Ti and 2-fold coordination for O atoms on the surfaces [77]. The lower coordinated bridging oxygen atoms at surface of (1 1 0) facet may form a minimum energy position for a single Pt atom.…”

Effect of step edges on the growth of Pt thin films on oxide single-crystal substrates

“…Although the E a of the Pt on the rutile TiO 2 (100) has not been determined, that on the rutile TiO 2 (110) was calculated to be 2.32 eV from DFT calculations. 15) The¸at 973 K was calculated to be 0.10 s. Because the¸was smaller than the time between the laser pulses, the calculated¸was determined as the t d . The diffusion length was estimated to be 400 nm.…”