Decomposition and protonation of surface ethoxys on TiO2(110)

Gamble, Lara J.; Jung, Linda S.; Campbell, Charles T.

doi:10.1016/0039-6028(95)00942-6

Cited by 141 publications

(291 citation statements)

References 24 publications

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“…Regarding the adsorption mode of ethanol, TPD and XPS studies have shown the dissociative adsorption on the Ti 5c sites at room temperature, 19,23,24 whereas mixed molecular and dissociative adsorptions have also been proposed at liquidnitrogen temperature using TPD and STM techniques. 18,20,21 Density functional theory (DFT) calculations have also not reached consensus yet. Nadeem et al 's calculations showed that the dissociative adsorption (O−H bond dissociation) of ethanol on Ti 5c sites is favored, 24,26 while Besenbacher and coworkers have shown that the molecular adsorption is more stable.…”

Section: Introductionmentioning

confidence: 99%

Photocatalytic Dissociation of Ethanol on TiO₂(110) by Near-Band-Gap Excitation

Guo

Mao

et al. 2013

J. Phys. Chem. C

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Ethanol on TiO 2 (110) has been studied using the temperature-programmed desorption (TPD), femtosecond two-photon photoemission spectroscopy (2PPE), and density functional theory (DFT) calculations. The first layer of ethanol (binds to Ti 5c ) whose molecular state has been predicted to be more stable by DFT desorbs at 295 K. A photoinduced excited state that is associated with bridging hydroxyls has been detected at ∼2.4 eV above the Fermi level on ethanol/ TiO 2 (110) interface using 2PPE. Detailed TPD studies show that ethanol on Ti 5c can be photocatalytically converted to acetaldehyde by near-band-gap excitation with the hydrogen atoms transfer to bridging-bonded oxygen sites, which is consistent with the 2PPE results. TPD results also show a low-temperature water TPD peak that seems to bind to the Ti 5c sites in addition to the ethylene TPD product. These results suggest that the Ti 5c sites on TiO 2 (110) are the primary active sites for photocatalysis of ethanol on TiO 2 (110), while bridging-bonded oxygen sites also play an important role, as in the case of methanol. The kinetics of photocatalyzed ethanol dissociation on TiO 2 (110) has also been measured using the 2PPE technique, which is of heterogeneous nature.

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Section: Introductionmentioning

confidence: 99%

Photocatalytic Dissociation of Ethanol on TiO₂(110) by Near-Band-Gap Excitation

Guo

Mao

et al. 2013

J. Phys. Chem. C

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“…In other studies, Thermal chemistry showed that there were mainly two reaction channels for ethanol desorption which lead to the suggestion of a mechanism involving the creation of new adsorption sites for water adsorption by means of a photothermaldesorption of adsorbed ethanol molecules [17]. The behavior of the preadsorption of water on the thermal desorption reaction of ethoxy has been reported by Gamble et al [25]. From these results we suggest that the adsorption of water and D2O are most likely to occur via photothermic rather than photoelectronic processes.…”

Section: Resultsmentioning

confidence: 85%

In Situ ATR-FTIR Investigation of the Effects of H₂O and D₂O Adsorption on the TiO₂Surface

et al. 2017

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We have investigated the behavior of H2O and D2O adsorption on TiO2 surfaces in the dark and under UV irradiation using insitu ATR-FTIR spectroscopy. The influence of an electron scavenger (oxygen) and a hole scavenger (ethanol) on the hydroxyl group and/or hydration water behavior on the TiO2 surface were also investigated. Adsorption of H2O-D2O mixtures revealed an isotopic exchange reaction occurring in the dark onto the surface of the TiO2 material. Under UV(A) irradiation, the quanitity of both OH and OD groups was found to be increased by the presence of molecular oxygen. On the other hand, the ATR-FTIR study of the ethanol adsorption in H2O and D2O revealed a stronger adsorption capacity for ethanol compared to both H2O and D2O resulting in molecular and dissociative adsorption of ethanol on the TiO2 surface. When the system was subsequently illuminated with UV(A) light, the surface becomes enriched with adsorbed water. Different possible mechanisms and hypotheses are discussed in terms of the effect of UV irradiation on the TiO2 particle network for the photocatalytic reaction and photoinduced hydrophilicity.

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“…23,24,39 After the hydroxyl hydrogen atoms (dissociated from ethanol) desorb from the surface as H 2 O by 500 K, a recombinative ethanol desorption of ethoxy (left on the surface) is suppressed because no hydrogen is left on the surface by that temperature. Instead, catalytic decompositions of such ethoxy species are reported to occur on TiO 2 (110) above 600 K. 22,24,26 We assume that oxygen vacancy is depleted on the oxidized surface due to dissociative adsorption of molecular oxygen, which would necessarily leave an oxygen adatom on the surface. We speculate that the C 1s species left after the annealing temperatures above 570 K is related to a dissociatively adsorbed ethoxy on a surface defect such as a low-coordinated oxygen adatom.…”

Section: +mentioning

confidence: 99%

“…11,[22][23][24] On the oxygen vacancy, the adsorption of ethanol proceeds by breaking O-H bond to produce ethoxy (CH 3 CH 2 O-) bound to the oxygen vacancy and hydrogen bound to a neighboring bridgebonded oxygen atom. 11,[22][23][24] A further catalytic decomposition of such alkoxy species can occur above 600 K through various competing reaction channels such as dehydration (alkene), dehydrogenation (aldehydes) and recombinative desorption (alcohol) as has been studied for simple aliphatic alcohols such as ethanol 24,25 and propanol.…”

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confidence: 99%

Photoemission Study on the Adsorption of Ethanol on Chemically Modified TiO₂(001) Surfaces

Kong¹,

Kim²

2011

Bulletin of the Korean Chemical Society

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Ethanol is a prototype molecule used in probing catalytic reactivity of oxide catalysts such as TiO 2 . In the present study, we adsorbed ethanol on TiO 2 (001) at room temperature (RT) and the corresponding bonding state of ethanol was systematically studied by x-ray photoemission spectroscopy (XPS) using synchrotron radiation. Especially, we compared TiO 2 (001) surfaces prepared in ultra-high vacuum (UHV) with different surface treatments such as Ar + -sputtering and oxidation with molecular O 2 , respectively. We find that the saturation coverage of ethanol at RT varies depending on the amount of reduced surface defects (e.g., Ti 3+ ) which are introduced by Ar + -sputtering. We also find that the oxidized TiO 2 (001) surface has other type of surface defects (not related to Ti 3d state) which can dissociate ethanol for further reaction above 600 K. Our C 1s core level spectra indicate clearly resolved features for the two chemically distinct carbon atoms from ethanol adsorbed on TiO 2 (001), showing the adsorption of ethanol proceeds without C-C bond dissociation. No other C 1s feature for a possible oxidized intermediate was observed up to the substrate temperature of 650 K.

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Decomposition and protonation of surface ethoxys on TiO2(110)

Cited by 141 publications

References 24 publications

Photocatalytic Dissociation of Ethanol on TiO₂(110) by Near-Band-Gap Excitation

Photocatalytic Dissociation of Ethanol on TiO₂(110) by Near-Band-Gap Excitation

In Situ ATR-FTIR Investigation of the Effects of H₂O and D₂O Adsorption on the TiO₂Surface

Photoemission Study on the Adsorption of Ethanol on Chemically Modified TiO₂(001) Surfaces

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Decomposition and protonation of surface ethoxys on TiO2(110)

Cited by 141 publications

References 24 publications

Photocatalytic Dissociation of Ethanol on TiO2(110) by Near-Band-Gap Excitation

Photocatalytic Dissociation of Ethanol on TiO2(110) by Near-Band-Gap Excitation

In Situ ATR-FTIR Investigation of the Effects of H2O and D2O Adsorption on the TiO2Surface

Photoemission Study on the Adsorption of Ethanol on Chemically Modified TiO2(001) Surfaces

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Resources

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Photocatalytic Dissociation of Ethanol on TiO₂(110) by Near-Band-Gap Excitation

Photocatalytic Dissociation of Ethanol on TiO₂(110) by Near-Band-Gap Excitation

In Situ ATR-FTIR Investigation of the Effects of H₂O and D₂O Adsorption on the TiO₂Surface

Photoemission Study on the Adsorption of Ethanol on Chemically Modified TiO₂(001) Surfaces