Adsorption and Photodesorption of CO from Charged Point Defects on TiO<sub>2</sub>(110)

Mu, Rentao; Dahal, Arjun; Wang, Zhitao; Dohnálek, Zdenek; Petrik, Nikolay G.; Lyubinetsky, Igor

doi:10.1021/acs.jpclett.7b02052

Cited by 22 publications

(32 citation statements)

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“…3(a)], the stability of the CO adsorption at nonpolaronic Ti 5c sites (i.e. CO+S1 configurations, down pointing triangles) increases with an increasing distance (a,b)] originate from a smaller number of available adsorption sites, as compared to the non-polaronic Ti 5c sites [39].…”

Section: (A)mentioning

confidence: 99%

“…CO adsorption on the rutile (110) surface is a well-studied phenomenon from both theoretical and experimental points of view [37][38][39][40][41][42][43], yet controversies appear even in elementary issues. Beyond a general consensus on the local geometric properties (CO molecules adsorb vertically at Ti 5c sites at low coverage) [37,38], conflicting outcomes have been reported, which either suggest [39] or exclude [40][41][42] the possibility of CO adsorption at V O sites, in the latter case endorsing a major role played by the fivefold-coordinated Ti 5c sites at S0. We show that the apparent disagreements in the literature can be resolved by a proper treatment of polarons and their interaction with adsorbates, by combining density functional theory (DFT) simulations [44,45] with scanning tunneling microscopy (STM) and atomic force microscopy (AFM).…”

mentioning

confidence: 99%

“…The effect of polarons is usually not considered in adsorption studies. CO adsorption on the rutile (110) surface is a well-studied phenomenon from both theoretical and experimental points of view [37][38][39][40][41][42][43], yet controversies appear even in elementary issues. Beyond a general consensus on the local geometric properties (CO molecules adsorb vertically at Ti 5c sites at low coverage) [37,38], conflicting outcomes have been reported, which either suggest [39] or exclude [40][41][42] the possibility of CO adsorption at V O sites, in the latter case endorsing a major role played by the fivefold-coordinated Ti 5c sites at S0.…”

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confidence: 99%

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Interplay between Adsorbates and Polarons: CO on Rutile TiO2(110)

Reticcioli¹,

Sokolović²,

Schmid³

et al. 2019

Phys. Rev. Lett.

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Polaron formation plays a major role in determining the structural, electrical and chemical properties of ionic crystals. Using a combination of first principles calculations and scanning tunneling microscpoy/atomic force microscopy (STM/AFM), we analyze the interaction of polarons with CO molecules adsorbed on the rutile TiO2(110) surface. Adsorbed CO shows attractive coupling with polarons in the surface layer, and repulsive interaction with polarons in the subsurface layer. As a result, CO adsorption depends on the reduction state of the sample. For slightly reduced surfaces, many adsorption configurations with comparable adsorption energies exist and polarons reside in the subsurface layer. At strongly reduced surfaces, two adsorption configurations dominante: either inside an oxygen vacancy, or at surface Ti5c sites, coupled with a surface polaron.

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confidence: 99%

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Interplay between Adsorbates and Polarons: CO on Rutile TiO2(110)

Reticcioli¹,

Sokolović²,

Schmid³

et al. 2019

Phys. Rev. Lett.

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“…In this work, we use the rutile TiO 2 (110) surface containing an O V and a CO molecule as a classic photocatalytic system to probe the interaction of EPs and adsorbates. Although experiments have demonstrated that defective rutile TiO 2 (110) with adsorbed CO exhibits good photocatalytic activity, 32 , 34 , 35 the dynamics of coupled CO and EPs have not been fully established. Such analysis is challenging for the following reasons.…”

Section: Introductionmentioning

confidence: 99%

CO Adsorbate Promotes Polaron Photoactivity on the Reduced Rutile TiO₂(110) Surface

Cheng

Zhu

Fang

et al. 2021

JACS Au

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Polarons play a major role in determining the chemical properties of transition-metal oxides. Recent experiments show that adsorbates can attract inner polarons to surface sites. These findings require an atomistic understanding of the adsorbate influence on polaron dynamics and lifetime. We consider reduced rutile TiO 2 (110) with an oxygen vacancy as a prototypical surface and a CO molecule as a classic probe and perform ab initio adiabatic molecular dynamics, time-domain density functional theory, and nonadiabatic molecular dynamics simulations. The simulations show that subsurface polarons have little influence on CO adsorption and CO can desorb easily. On the contrary, surface polarons strongly enhance CO adsorption. At the same time, the adsorbed CO attracts polarons to the surface, allowing them to participate in catalytic processes with CO. The CO interaction with polarons changes their orbital origin, suppresses polaron hopping, and stabilizes them at surface sites. Partial delocalization of polarons onto CO decouples them from free holes, decreasing the nonadiabatic coupling and shortening the quantum coherence time, thereby reducing charge recombination. The calculations demonstrate that CO prefers to adsorb at the next-nearest-neighbor five-coordinated Ti 3+ surface electron polaron sites. The reported results provide a fundamental understanding of the influence of electron polarons on the initial stage of reactant adsorption and the effect of the adsorbate–polaron interaction on the polaron dynamics and lifetime. The study demonstrates how charge and polaron properties can be controlled by adsorbed species, allowing one to design high-performance transition-metal oxide catalysts.

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“…22 Recent scanning tunneling microscopy (STM) studies have demonstrated that CO molecules adsorb preferentially at or near particular defect sites (V O or OH b ) on reduced or hydroxylated rutile TiO 2 (110) surfaces (r-TiO 2 (110) or h-TiO 2 (110), respectively). 26,27 However, the differences in the CO binding energies between the various adsorption sites are quite small (<0.02 eV). 27 UV irradiation leads to CO desorption from TiO 2 (110).…”

Section: Introductionmentioning

confidence: 99%

Diffusion and Photon-Stimulated Desorption of CO on TiO₂(110)

Petrik

Dahal

et al. 2018

J. Phys. Chem. C

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Thermal diffusion of CO adsorbed on rutile TiO 2 (110) was studied in the 20−110 K range using photon-stimulated desorption (PSD), temperatureprogrammed desorption (TPD), and scanning tunneling microscopy. During UV irradiation, CO desorbs from certain photoactive sites (e.g., oxygen vacancies). This phenomenon was exploited to study CO thermal diffusion in three steps: first, empty these sites during a first irradiation cycle, then replenish them with CO during annealing, and finally probe the active site occupancy in the second PSD cycle. The PSD and TPD experiments show that the CO diffusion rate correlates with the CO adsorption energystronger binding corresponds to slower diffusion. Increasing the CO coverage from 0.06 to 0.44 monolayer (ML) or hydroxylation of the surface decreases the CO binding and increases the CO diffusion rate. Relative to the reduced surface, the CO adsorption energy increases and the diffusion decreases on the oxidized surface. The CO diffusion kinetics can be modeled satisfactorily as an Arrhenius process with a "normal" prefactor (i.e., ν = 10 12 s −1 ) and a Gaussian distribution of activation energies where the peak of the distribution is ∼0.26 eV and the full width at half-maximum (fwhm) is ∼0.1 eV at the lowest coverage. The observations are consistent with a significant electrostatic component of the CO binding energy on the TiO 2 (110) surface which is affected by changes in the surface dipole and dipole−dipole interactions.

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Adsorption and Photodesorption of CO from Charged Point Defects on TiO₂(110)

Cited by 22 publications

References 49 publications

Interplay between Adsorbates and Polarons: CO on Rutile TiO2(110)

Interplay between Adsorbates and Polarons: CO on Rutile TiO2(110)

CO Adsorbate Promotes Polaron Photoactivity on the Reduced Rutile TiO₂(110) Surface

Diffusion and Photon-Stimulated Desorption of CO on TiO₂(110)

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Adsorption and Photodesorption of CO from Charged Point Defects on TiO2(110)

Cited by 22 publications

References 49 publications

Interplay between Adsorbates and Polarons: CO on Rutile TiO2(110)

Interplay between Adsorbates and Polarons: CO on Rutile TiO2(110)

CO Adsorbate Promotes Polaron Photoactivity on the Reduced Rutile TiO2(110) Surface

Diffusion and Photon-Stimulated Desorption of CO on TiO2(110)

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Adsorption and Photodesorption of CO from Charged Point Defects on TiO₂(110)

CO Adsorbate Promotes Polaron Photoactivity on the Reduced Rutile TiO₂(110) Surface

Diffusion and Photon-Stimulated Desorption of CO on TiO₂(110)