Diffusion versus Desorption: Complex Behavior of H Atoms on an Oxide Surface

Yin, Xiuli; Calatayud, Mònica; Qiu, Han‐Yue; Wang, Y.; Birkner, Alexander; Minot, Christian; Wöll, Christof

doi:10.1002/cphc.200700612

Cited by 130 publications

(216 citation statements)

References 32 publications

Supporting

Mentioning

190

Contrasting

Order By: Relevance

“…The TPD spectra of these products have maxima near 450 K and the magnitudes of the signals clearly depend on the laser irradiation time. The observed TPD spectra for H 2 O, HOD, and D 2 O are very similar to the H 2 O TPD peak that is known to originate from H atoms adsorbed on the BBO sites of TiO 2 (110), 38 suggesting that the TPD signals of all the water isotopologues that we observe also come from BBO sites with adsorbed H and D atoms, which are produced by photocatalyzed dissociation of CD 3 OH on Ti 5c sites. The TPD signal as a function of laser irradiation time for the different water isotopologues provides a comparison between the rates of producing hydrogen atoms bound to bridge-bonded oxygen atoms (BBO-H) and deuterium atoms bound to bridge-bonded oxygen atoms (BBO-D).…”

Section: ■ Computational Methodssupporting

confidence: 67%

Stepwise Photocatalytic Dissociation of Methanol and Water on TiO₂(110)

et al. 2012

View full text Add to dashboard Cite

ABSTRACT:We have investigated the photocatalysis of partially deuterated methanol (CD 3 OH) and H 2 O on TiO 2 (110) at 400 nm using a newly developed photocatalysis apparatus in combination with theoretical calculations. Photocatalyzed products, CD 2 O on Ti 5c sites, and H and D atoms on bridge-bonded oxygen (BBO) sites from CD 3 OH have been clearly detected, while no evidence of H 2 O photocatalysis was found. The experimental results show that dissociation of CD 3 OH on TiO 2 (110) occurs in a stepwise manner in which the O−H dissociation proceeds first and is then followed by C−D dissociation. Theoretical calculations indicate that the high reverse barrier to C−D recombination and the facile desorption of CD 2 O make photocatalytic methanol dissociation on TiO 2 (110) proceed efficiently. Theoretical results also reveal that the reverse reactions, i.e, O−H recombination after H 2 O photocatalytic dissociation on TiO 2 (110), may occur easily, thus inhibiting efficient photocatalytic water splitting. ■ INTRODUCTIONTitanium dioxide has been extensively investigated as a catalyst or photocatalyst, 1−11 particularly in applications involving photodegradation of organic molecules and water splitting, 5,12,13 which have important implications in environmental remediation and clean energy. Pure TiO 2 is apparently not photocatalytically active for splitting water to produce hydrogen, 14 but the addition of methanol to water can dramatically enhance the photocatalytic activity for hydrogen production. 15 Therefore, understanding the key differences between the photocatalytic chemistry of methanol and water on a model TiO 2 surface at the molecular level may provide valuable insight into the dynamics of photocatalysis that would enhance efforts for developing new and efficient photocatalysts for water splitting.Theoretical and experimental studies often focus on TiO 2 (110) as a model surface, 6,16 with the methanol/ TiO 2 (110) system serving as a model for photocatalysis on TiO 2 . 17−20 Henderson and co-workers 18 conducted a temperature-programmed desorption (TPD) study of CH 3 OH on TiO 2 (110) and concluded that the majority of the CH 3 OH molecules are adsorbed in molecular form. This conclusion is consistent with a scanning tunneling microscopy study by Dohnalek et al. 10 that showed that methanol molecules are adsorbed molecularly on the Ti 5c sites and are dissociated only at bridge-bonded oxygen (BBO) vacancy sites. The photocatalysis of CH 3 OH on TiO 2 (110) was investigated in a twophoton photoemission (2PPE) experiment, which inferred the presence of an excited electronic state on the surface. 20,21 Zhou et al. attributed this surface state to a photocatalytic dissociated state of methanol using a time-dependent 2PPE (TD-2PPE) technique. 22 They also used a combination of photoexcitation with STM and found that 400 nm light could induce dissociation of methanol on the surface, and they assigned the dissociated state as methoxy (CH 3 O) on a Ti 5c site and a hydrogen atom on a BBO site. Shen and Hend...

show abstract

Section: ■ Computational Methodssupporting

confidence: 67%

Stepwise Photocatalytic Dissociation of Methanol and Water on TiO₂(110)

et al. 2012

View full text Add to dashboard Cite

show abstract

“…In accord with the theoretical calculations, this vibration is assigned to an H-atom bound to a surface bridging O 2c site. The frequency of this OH br species is rather similar to that of hydroxyls formed on the same surface after exposure to atomic hydrogen [30] or after H 2 O dissociation at surface O vacancies [31,32].…”

Section: Discussionmentioning

confidence: 75%

Interaction of carboxylic acids with rutile TiO2(110): IR-investigations of terephthalic and benzoic acid adsorbed on a single crystal substrate

Buchholz

Noei

et al. 2016

Surface Science

View full text Add to dashboard Cite

a b s t r a c t a r t i c l e i n f oThe adsorption of two carboxylic acids, benzoic acid (BA) and terephthalic acid (TPA), on a single crystal rutile TiO 2 (110) substrate was studied using infrared reflection-absorption spectroscopy (IRRAS) in conjunction with DFT calculations. On the basis of the high-quality IR data (in particular for the OH bands), various adsorbate species with different geometries could be identified. The adsorption of both, BA and TPA, on TiO 2 (110) leads to deprotonation of carboxylic acids and protonation of substrate O-atoms. At low coverage, the deprotonated BA molecule adsorbs on TiO 2 (110) in an upright, bidentate configuration, while the TPA molecule adopts a flatlying geometry with both carboxylates bound to the surface in a monodentate geometry. At higher coverages, a transition from flat-lying to upright-oriented TPA molecules occurs. At saturation coverage, both BA and TPA molecules undergo dimerization indicating the presence of pronounced attractive intermolecular interactions. We propose that the BA dimers are stabilized by the interaction between adjacent phenyl rings, while the TPA dimerization is attributed to the formation of double hydrogen bonds between adjacent apical carboxylic groups.

show abstract

“…As the STM and LEED results of Li and Diebold show a c(2x2) molecular overlayer, consistent with a coverage of the molecular species of 0.5 ML, achieving this coverage of phenyl imide from aniline would release 1 ML of atomic hydrogen. The absence of any significant OH feature in the O 1s spectrum indicates that the hydroxyl coverage must be very significantly less than 1 ML, so only a small fraction of the released H atoms can be bonded to the surface oxygen atoms and we can only surmise that most (or all) of the H atoms are desorbed as H 2 or are absorbed below the surface; on the basis of previous studies of hydrogen absorption and desorption [13,14], the latter option seems the more probable. Fig.…”

Section: Experimental and Computational Detailsmentioning

confidence: 82%

The local structure of the azobenzene/aniline reaction intermediate on TiO2(110)

et al. 2013

View full text Add to dashboard Cite

Scanned-energy mode photoelectron diffraction (PhD) and near-edge X-ray absorption fine structure (NEXAFS) have been used to study the surface species, previously proposed to be phenyl imide, C 6 H 5 N-, on rutile TiO 2 (110) following exposure to either azobenzene or aniline. All measurements are consistent with the two reactants forming a common surface species in the same local adsorption site. N K-edge NEXAFS confirms the scission of the N=N bond in azobenzene, while C K-edge NEXAFS shows the phenyl ring to be intact with the molecular plane tilted relative to the surface normal and not aligned in either principle azimuth of the surface. N 1s PhD data indicate that the N atom bonds atop a surface five-fold-coordinated Ti atom, most probably at a Ti-N bondlength of 1.770.05 Å, and not bridging two such atoms, as had been suggested. This atop geometry is favoured by recent density functional theory (DFT) calculations, but more quantitative aspects of the DFT result are not in agreement with the conclusions of our experimental study.

show abstract

Diffusion versus Desorption: Complex Behavior of H Atoms on an Oxide Surface

Cited by 130 publications

References 32 publications

Stepwise Photocatalytic Dissociation of Methanol and Water on TiO₂(110)

Stepwise Photocatalytic Dissociation of Methanol and Water on TiO₂(110)

Interaction of carboxylic acids with rutile TiO2(110): IR-investigations of terephthalic and benzoic acid adsorbed on a single crystal substrate

The local structure of the azobenzene/aniline reaction intermediate on TiO2(110)

Contact Info

Product

Resources

About

Diffusion versus Desorption: Complex Behavior of H Atoms on an Oxide Surface

Cited by 130 publications

References 32 publications

Stepwise Photocatalytic Dissociation of Methanol and Water on TiO2(110)

Stepwise Photocatalytic Dissociation of Methanol and Water on TiO2(110)

Interaction of carboxylic acids with rutile TiO2(110): IR-investigations of terephthalic and benzoic acid adsorbed on a single crystal substrate

The local structure of the azobenzene/aniline reaction intermediate on TiO2(110)

Contact Info

Product

Resources

About

Stepwise Photocatalytic Dissociation of Methanol and Water on TiO₂(110)

Stepwise Photocatalytic Dissociation of Methanol and Water on TiO₂(110)