TiO2 , reduced

To explore the possibility of electronic Interaction between the reduced titanium oxide and Pt, 1 ML of Pt was deposited on both fully oxidized and partially reduced T102. The reduced sample was prepared by Ar" " sputtering of the TIO2 substrate prior to metal deposition. Introducing reduced Tl centers at the Pt-Tl Interface. 

Recently, it has been demonstrated that coordination vacancies on the surface metal cations are relevant to the unique redox reactivity of oxide surfaces]2]. Oxidation of fonnaldehyde and methyl formate to adsorbed formate intermediates on ZnO(OOOl) and reductive C-C coupling of aliphatic and aromatic aldehydes and cyclic ketones on 1102(001) surfaces reduced by Ar bombardment are observed in temperature-prognunmed desorption(TPD). The thermally reduced 1102(110) surface which is a less heavily damaged surface than that obtained by bombardment and contains Ti cations in the -t-3 and +4 states, still shows activity for the reductive coupling of formaldehyde to form ethene]13]. Interestingly, the catalytic cyclotrimerization of alkynes on TiO2(100) is also traced in UHV conditions, where cation coordination and oxidation states appear to be closely linked to activity and selectivity. The nonpolar Cu20( 111) surface shows a... 

Recently, we have shown that the combination of barium tetratitanate, BaTi40g and sodium hexatitanate, NagTigOis, with ruthenium oxides leads to active photocatalysts for water decomposition[1,2]. The unique feature of these photocatalysts is that no reduction of the titanates is required to be activated this is intrinsically different from conventional photocatalysts using TIO2 which are often heat-treated in a reducing atmosphere. Such different photocatalytic characteristics suggest that efficiency for the separation of photoexcited charges (a pair of electrons and holes) which is the most important step in photocatalysis is... 

We have previously demonstrated the stoichiometric cyclotrimerization of a variety of alkynes on reduced TiO2(001) surfaces in UHV using TPD [1,2]. A... 

Okazawa T, Kohyama M, Kido Y. 2006. Electronic properties of Au nano-particles supported on stoichiometric and reduced TiO2(110) substrates. Surf Sci 600 4430-4437. 

Evidence for the occurrence of an electronic interaction between V and W has been reported, possibly involving the semiconductor character of the TiO2 support and leading to a different reducibility of the catalysts. 

The photodegradation rate dependence on phenol concentration in the TiOi/F system shows a plateau in the 3 X IO " M to 3 X 10 M range, whereas for naked TiO2, a maximum is reached around 2 X 10 M of phenol followed by a decrease. This behavior is rationalized by the possibility of reductive back reactions of intermediates formed after the first oxidation step. The presence of fluoride could limit the occurrence of this detrimental effect, reducing the interaction of the formed intermediates with the surface. Moreover, also the change of the oxidation pathway changes the amount of the products. 

Scheme 1 illustration of the interfacial charge-transfer processes in nanocrystalline dye sensitized solar cell. S, S, and S represents the sensitizer in the ground, oxidized, and excited states, respectively. Visible light absorption by the sensitizer (1) leads to an excited state, followed by electron injection (2) onto the conduction band of TiO2. The oxidized sensitizer (3) is reduced by the I /I redox couple (4). The injected electrons into the conduction band may react either with the oxidized redox couple (5) or with oxidized dye molecule (6). 

The formation of formaldehyde from formic acid is not expected to occur on stoichiometric TiO2(110) because the surface cations are exclusively five-coordinate, and formaldehyde formation in the absence of reduced surface sites has been shown to be dependent on the presence of low-coordinate metal cations on titanium dioxide surfaces. Iwasawa et al. noted the absence of formaldehyde from the product slate of formic acid reaction products in their studies on the TiO2(110) surface [43]. 

The extent of lattice oxygen incorporation into the decomposition products is linked to the surface redox properties of the oxide. Recent SSIMS and FT-RAIRS studies have provided initial evidence for the transient formation of oxygen vacancies on the surface of TiO2(110). Henderson has proposed that surface oxygen vacancies may explain the formation of trace amounts of formaldehyde from formic acid on Ti02(l 10) (figure 3) [41]. Both reactions (6) and (7) are proposed to occur below 500 K the water produced from formic acid exposure desorbed at 475 K, before the onset of formate decomposition to form CO. Formaldehyde and CO2 were produced in minor quantities relative to the production of CO [41]. Formaldehyde was formed from formic acid on reduced... 

Reduced cation oxidation states can drive reduction reactions of oxygenated adsorbates. Sputter-reduced surfaces of TiO2(001) readily converted formic acid into formaldehyde and methanol into methane and CO. 

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