Formic Acid Adsorption on Dry and Hydrated TiO<sub>2</sub> Anatase (101) Surfaces by DFT Calculations

Vittadini, Andrea; Selloni, Annabella; Rotzinger, François P.; Gräetzel, Michael

doi:10.1021/jp993583b

Cited by 414 publications

(455 citation statements)

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“…18 These spectral changes have been found to be compatible with chelating and/or bidentate binding modes of the carboxylate groups on the TiO 2 surface. 18,[23][24][25][26] The IR spectrum of m-ZnTCPP/TiO 2 was consistent with the absence of free carboxylic acid groups, given that C]O and C-O stretching modes disappeared completely. This suggests a planar situation of the porphyrin macrocycle with respect to the titania surface in which all carboxyl groups are bound to the TiO 2 .…”

Section: Resultsmentioning

confidence: 71%

Anchoring effect on (tetra)carboxyphenyl porphyrin/TiO₂composite films for VOC optical detection

et al. 2014

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The optical gas sensing properties of Zn-(II) -5,10,15,20-tetra(3-carboxyphenyl)porphyrin (m-ZnTCPP) and Zn-(II)-5,10,15,20-tetra(4-carboxyphenyl)porphyrin (p-ZnTCPP) bound to microcolumnar TiO 2 thin films have been compared and explained in terms of their different molecular structure and anchoring to the titania surface. This different binding has been confirmed by specular reflectance FTIR revealing that m-ZnTCPP is bound by its four carboxylic groups in contrast to p-ZnTCPP where two or three of these groups remain unanchored. As a consequence, the Soret band of the para derivative is blue shifted with respect to the solution, indicating H aggregation, while m-ZnTCPP remained in its monomeric form due to the planar anchoring by the four COOH groups to the titania matrix that would avoid porphyrin aggregation. The sensing performance of the two systems has been assessed by analyzing the spectral changes in their UV-visible spectra under exposure to six volatile organic compounds. Although the highly porous and non-dispersive TiO 2 matrix allow good sensing ability in both cases, the response of the m-ZnTCPP/TiO 2 composite has been found to be more intense and faster than that of p-ZnTCPP.Moreover, the use of identification patterns also indicates that the meta derivative achieves a more selective recognition of the selected analytes. This improvement in the sensing capabilities of m-ZnTCPP has been attributed to the absence of aggregation between adjacent macrocycles.

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Section: Resultsmentioning

confidence: 71%

Anchoring effect on (tetra)carboxyphenyl porphyrin/TiO₂composite films for VOC optical detection

et al. 2014

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“…34,[44][45][46][47] We therefore determined, in the first step, the geometry of deposition through BB-type adsorption, using periodic slab model for vacuum and cluster method for solvent calculations. The optimized geometries of deposition on (TiO2) 38 cluster surface in acetonitrile is shown in Fig.…”

Section: Ct-character Excited States and Solvatochromic Shiftsmentioning

confidence: 99%

Efficiency enhancement of black dye-sensitized solar cells by newly synthesized D–π–A coadsorbents: a theoretical study

Azar

Payami

2014

Phys. Chem. Chem. Phys.

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In this work, using the DFT and TDDFT, we have theoretically studied the electronic and optical properties of the two recently synthesized coadsorbents Y1 and Y2, which were aimed to enhance the efficiency of the black dye-sensitized solar cells. To determine the solvatochromic shifts, both the implicit and mixed implicit-explicit models have been used. The connection between the solvatochromic shifts and the changes of dipole moments in the excitation process is discussed. The difference in excitation charge transfer is utilized to explain the experimentally observed difference in J sc for Y1 and Y2. Investigating the interactions of I 2 molecules in the electrolyte solution with the coadsorbents showed that with Y1 the recombination loss was weakened through decreasing the I 2 concentration near the TiO 2 surface, whereas with Y2 it was increased. As a result, the higher values of both J sc and V oc with Y1 coadsorbent explains its experimentally observed higher efficiency. The present study sheds light on how to design and engineer newer coadsorbents or organic dyes for higher efficiencies.

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“…6 Formate adsorption on TiO 2 has been studied extensively. [8][9][10][11][12][13][14][15][16][17][18][19][20][21] Previous studies of adsorption of formic acid (HCOOH) on rutile TiO 2 (110) surfaces have shown that upon adsorption it dissociates into a formate ion (HCOO -) and a proton (H + ), which bind to lowcoordinated Ti and O surface atoms, respectively. 22,23 The adsorption structure of small molecules, such as HCOOH, can be studied favourably by infrared spectroscopy, and in particular infrared reflection-absorption spectroscopy (IRRAS) has been employed to study e.g.…”

Section: Introductionmentioning

confidence: 99%

Adsorption of formic acid on rutile TiO2 (110) revisited: An infrared reflection-absorption spectroscopy and density functional theory study

Mattsson

Hermansson

et al. 2014

The Journal of Chemical Physics

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Adsorption of formic acid on rutile TiO2 (110) revisited: An infrared reflection-absorption spectroscopy and density functional theory study. Journal of Chemical Physics AbstractFormic acid (HCOOH) adsorption on rutile TiO 2 (110) has been studied by s-and p-polarized infrared reflection-absorption spectroscopy (IRRAS) and spin-polarized density functional theory together with Hubbard U contributions (DFT+U) calculations. To compare with IRRAS spectra, the results from the DFT+U calculations were used to simulate IR spectra by employing a three-layer model, where the adsorbate layer was modelled using Lorentz oscillators with calculated dielectric constants. To account for the experimental observations, four possible formate adsorption geometries were calculated, describing both the perfect (110) surface, and surfaces with defects; either O vacancies or hydroxyls. The binding energy was found to be E bind = 1.84 eV for the bridging bidentate formate species, which bonds with its IRRAS spectra measured on surfaces prepared to be either reduced, stoichiometric, or to contain surplus O adatoms, were found to be very similar. By comparisons with computed spectra, it is concluded that formate binds to in-plane Ti 5c atoms rather than to O vacancy sites. The results emphasize the importance of protonation and reactive surface hydroxylseven under UHV conditions -as reactive sites in e.g. catalytic applications.

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Formic Acid Adsorption on Dry and Hydrated TiO₂ Anatase (101) Surfaces by DFT Calculations

Cited by 414 publications

References 38 publications

Anchoring effect on (tetra)carboxyphenyl porphyrin/TiO₂composite films for VOC optical detection

Anchoring effect on (tetra)carboxyphenyl porphyrin/TiO₂composite films for VOC optical detection

Efficiency enhancement of black dye-sensitized solar cells by newly synthesized D–π–A coadsorbents: a theoretical study

Adsorption of formic acid on rutile TiO2 (110) revisited: An infrared reflection-absorption spectroscopy and density functional theory study

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Formic Acid Adsorption on Dry and Hydrated TiO2 Anatase (101) Surfaces by DFT Calculations

Cited by 414 publications

References 38 publications

Anchoring effect on (tetra)carboxyphenyl porphyrin/TiO2composite films for VOC optical detection

Anchoring effect on (tetra)carboxyphenyl porphyrin/TiO2composite films for VOC optical detection

Efficiency enhancement of black dye-sensitized solar cells by newly synthesized D–π–A coadsorbents: a theoretical study

Adsorption of formic acid on rutile TiO2 (110) revisited: An infrared reflection-absorption spectroscopy and density functional theory study

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Product

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Formic Acid Adsorption on Dry and Hydrated TiO₂ Anatase (101) Surfaces by DFT Calculations

Anchoring effect on (tetra)carboxyphenyl porphyrin/TiO₂composite films for VOC optical detection

Anchoring effect on (tetra)carboxyphenyl porphyrin/TiO₂composite films for VOC optical detection