Elementary steps and site requirements in formic acid dehydration reactions on anatase and rutile TiO2 surfaces

Kwon, Stephanie; Lin, Ting; Iglesia, Enrique

doi:10.1016/j.jcat.2019.12.043

Cited by 34 publications

(48 citation statements)

References 46 publications

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“…7 The difference between PBE and SCAN predictions can be attributed to the partial inclusion of vdW interactions in the latter functional; 21,22,26 PBE calculations including vdW corrections predict indeed the BD configuration to be most stable. 19 We investigated low coverage FA adsorption under wet conditions using a four tri-layers A-101 (4 × 1) slab with one adsorbed BD formate and one accompanying O br H on each surface while the water environment was represented by 75 molecules at the experimental density of 1 g/cm 3 . Figure 2a shows a snapshot and the average water density profile of this interface (denoted I1 in the following) as given by our AIMD simulation.…”

mentioning

confidence: 99%

Hydrogen Bonds and H₃O⁺ Formation at the Water Interface with Formic Acid Covered Anatase TiO₂

Wen

Selloni

2021

J. Phys. Chem. Lett.

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Carboxylic acid-modified TiO2 surfaces in aqueous environment are of widespread interest, yet atomic-scale understanding of their structure is limited. We here investigate formic acid (FA) on anatase TiO2 (101) (A-101) in contact with water using density functional theory (DFT) and ab initio molecular dynamics (AIMD). Isolated FA molecules adsorbed in a deprotonated bridging bidentate (BD) form on A-101 are found to remain stable at the interface with water, with the acid proton transferred to a surface oxygen to form a surface bridging hydroxyl (ObrH). With increasing FA coverage, adsorbed monolayers of only BD and successively of alternating monodentate (MD) and BD species give rise to a higher concentration of surface ObrH’s. Simulations of these adsorbed monolayers in water environment show that some protons are released from the surface ObrH’s to water resulting in a negatively charged surface with nearby solvated H3O+ ions. These results provide insight into the complex acid–base equilibrium between an oxide surface, adsorbates and water and can also help obtain a better understanding of the wetting properties of chemically modified TiO2 surfaces.

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confidence: 99%

Hydrogen Bonds and H₃O⁺ Formation at the Water Interface with Formic Acid Covered Anatase TiO₂

Wen

Selloni

2021

J. Phys. Chem. Lett.

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“…However, the acid-base properties of both these TiO 2 phases are different. Whereas both rutile and anatase TiO 2 phases have mainly Lewis acid sites [41,42], Kwon et al [43] and our recent work [44] show that TiO 2 rutile has the stronger acid strength. Actually, we have found that TiO 2 rutile R100 has a stronger Lewis acid site density (0.82 µmol/m 2 for R100) when compared to TiO 2 anatase A100 but also to P25 and P90 which have respectively 0.47 µmol/m 2 , 0.18 µmol/m 2 and 0.16 µmol/m 2 [44].…”

Section: Impact Of Anatase Versus Rutile Phase On the Formation Of Ac...mentioning

confidence: 56%

Acetal photocatalytic formation from ethanol in the presence of TiO2 rutile and anatase

Betts

Dappozze

Hamandi

et al. 2022

Photochem Photobiol Sci

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The decomposition of ethanol, one of the most important biomass platform molecules, was investigated under green conditions, ambient temperature, atmospheric pressure and air for the synthesis of acetal in the presence of TiO 2 activated under UV-A radiation. The impact of ethanol concentration, of the nature of TiO 2 (rutile, anatase or mixture), of the photodeposition of Pt under air or argon were all factors under investigation. Whatever the conditions and the nature of catalyst used, acetaldehyde was initially formed before reacting with ethanol to form acetal, a promising fuel additive. However, the subsequent generation of acetal differs depending on the conditions and the nature of catalyst. In the absence of a noble metal, rutile TiO 2 leads to an increase in acetal formation at equivalent acetaldehyde formation. This behavior is discussed considering the acidic and basic properties of rutile and anatase phases together with H + generated under UV. In the presence of Pt, under air or Ar, the acetal formation begins at a lower concentration of acetaldehyde due to the in-situ photodeposition of Pt. However, whereas acetal formation is similar for Pt/anatase and Pt/rutile phase under air, under Ar, less acetal is generated on Pt/rutile in agreement with the production of more H 2 .

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“…When the HCOOH was introduced to the in situ cell, the intensity of HCOOH*, HCOO*, gas CO 2 and CO bridged adsorption to the Pd site strengthened in the initial 15 min and basically kept unchanged after achieving steady sate. In this HCOOH adsorption process, vibration modes at 3585, 3550 cm −1 were assigned to the O−H stretching vibration mode, the features at 2938 cm −1 were assigned to the C−H bond stretching vibration mode, the features at 1791 and 1762 cm −1 were attributed to C=O stretching vibration mode, and the features at 1119, 1106 and 1089 cm −1 were assigned to C−O stretching vibration mode of the surface HCOOH species (Figure 4a, Figure 4b, Figure S15b and S15c) [16,34] . Besides, specially, the peak at around 1244, 1225, 1197 cm −1 were assigned to the coupled vibration mode of the C−O bond and the deformation vibration mode from the O−H bond showing a broad band, which can be attributed to the reason that this peak is sensitive to absorbed HCOOH* with different conformers (the cis HCOOH with deformation vibration of C−O and C−OH is at 1244 cm −1 and this peak for trans HCOOH is at 1216 cm −1 and this band for HCOOH dimer is at 1187, 1225, 1259 cm −1 ) [35] .…”

Section: Resultsmentioning

confidence: 99%

“…In this HCOOH adsorption process, vibration modes at 3585, 3550 cm À 1 were assigned to the OÀ H stretching vibration mode, the features at 2938 cm À 1 were assigned to the CÀ H bond stretching vibration mode, the features at 1791 and 1762 cm À 1 were attributed to C=O stretching vibration mode, and the features at 1119, 1106 and 1089 cm À 1 were assigned to CÀ O stretching vibration mode of the surface HCOOH species (Figure 4a, Figure 4b, Figure S15b and S15c). [16,34] Besides, specially, the peak at around 1244, 1225, 1197 cm À 1 were assigned to the coupled vibration mode of the CÀ O bond and the deformation vibration mode from the OÀ H bond showing a broad band, which can be attributed to the reason that this peak is sensitive to absorbed HCOOH* with different conformers (the cis HCOOH with deformation vibration of CÀ O and CÀ OH is at 1244 cm À 1 and this peak for trans HCOOH is at 1216 cm À 1 and this band for HCOOH dimer is at 1187, 1225, 1259 cm À 1 ). [35] The other typical frequencies at 2875, 1584 and 1362 cm À 1 could be attributed to CÀ H stretching vibration (ν CÀ H ), asymmetrical stretching vibration of COO functional group (ν as COO ) and symmetrical stretching vibration of COO (ν s COO ) within HCOO*, respectively (Figure 4a, b and S15a).…”

Section: Pressure Dependence Studies About Hcooh Decomposition Driven...mentioning

confidence: 99%

“…[15] At the same time, Iglesia et al reported that CÀ H rupture is the RDS over TiO 2 supported Pt, Au catalysts in HCOOH decomposition reaction driven by thermal energy. [16] Although much effort has been devoted to investigating the photo or thermal-catalytic HCOOH decomposition mechanism, describing in detail the RDS confirmed by KIE and pressure dependence studies under photo-thermal catalytic conditions is still lacking.…”

Section: Introductionmentioning

confidence: 99%

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Evidence of Kinetically Relevant Consistency in Thermal and Photo‐Thermal HCOOH Decomposition over Pd/LaCrO₃/C₃N₄ Composite

Yuan

Guo

Che

et al. 2022

Chemistry A European J

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Photo-thermal catalysis has been an attractive alternative strategy to promote chemical reactions for years, however, how light cooperates with thermal energy is still unclear. We meet this demand by exploring reaction mechanism via pressure dependency studies as well as H/D exchange experiments with HCOOH decomposition as a probe over a palladium nanoparticle (Pd n ) and isolated Pd (Pd 1 ) decorated LaCrO 3 /C 3 N 4 composite catalyst, in which the H 2 formation rate shows a first-order dependence on HCOOH and inverse first-order dependence on CO partial pressures no matter the reaction was driven by thermal or photothermal energy. Additionally, negligible kinetic isotopic effects (KIEs: k H /k D ) were determined under both dark and light conditions at 1.04 and 1.18 when the HCOOH was replaced by HCOOD. Besides, when the reactant HCOOH was further replaced by DCOOD, the KIE values of 1.55 (dark) and 1.92 (light) were obtained, which indicates that the HCOOH decomposition follows kinetically relevant (KR) of CÀ H bond rupture within HCOOH molecule under both thermal and photo-thermal reaction conditions and the catalytic surface was found to be densely covered by CO based on the pressure dependency studies as well as the in situ Fourier transform infrared spectroscopy (FTIR) analysis. Clearly, the HCOOH decomposition driven by thermal and photo-thermal energy follows the same reaction mechanism. Nevertheless, light induced hot electrons and the derived thermal effect do cause the enhancement of the reaction activity in some circumstances compared with bare thermal catalysis, which clarifies the confusion on cooperation mechanism of photo and thermal energies from the kinetic perspective. Hot electrons induced by photo-illumination was confirmed by in situ FTIR CO chemisorption with ~10 cm À 1 redshift identified of the CO feature once light was introduced. Meanwhile, the photo thermal reaction system suffers from severe electron-hole re-combination at high reaction temperatures and make the thermal effect of photo irradiation dominant with respect to the effect at low reaction temperatures. This research provides insight to the mechanism on how photothermal reaction works and draws attention to the photothermal reaction process in boosting catalytic activity.

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Elementary steps and site requirements in formic acid dehydration reactions on anatase and rutile TiO2 surfaces

Cited by 34 publications

References 46 publications

Hydrogen Bonds and H₃O⁺ Formation at the Water Interface with Formic Acid Covered Anatase TiO₂

Hydrogen Bonds and H₃O⁺ Formation at the Water Interface with Formic Acid Covered Anatase TiO₂

Acetal photocatalytic formation from ethanol in the presence of TiO2 rutile and anatase

Evidence of Kinetically Relevant Consistency in Thermal and Photo‐Thermal HCOOH Decomposition over Pd/LaCrO₃/C₃N₄ Composite

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Elementary steps and site requirements in formic acid dehydration reactions on anatase and rutile TiO2 surfaces

Cited by 34 publications

References 46 publications

Hydrogen Bonds and H3O+ Formation at the Water Interface with Formic Acid Covered Anatase TiO2

Hydrogen Bonds and H3O+ Formation at the Water Interface with Formic Acid Covered Anatase TiO2

Acetal photocatalytic formation from ethanol in the presence of TiO2 rutile and anatase

Evidence of Kinetically Relevant Consistency in Thermal and Photo‐Thermal HCOOH Decomposition over Pd/LaCrO3/C3N4 Composite

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Product

Resources

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Hydrogen Bonds and H₃O⁺ Formation at the Water Interface with Formic Acid Covered Anatase TiO₂

Hydrogen Bonds and H₃O⁺ Formation at the Water Interface with Formic Acid Covered Anatase TiO₂

Evidence of Kinetically Relevant Consistency in Thermal and Photo‐Thermal HCOOH Decomposition over Pd/LaCrO₃/C₃N₄ Composite