Effect of oxygen vacancy sites on CO2 adsorption dynamics: The case of rutile (1×1)-TiO2 (110)

Funk, S.; Hokkanen, B.; Johnson, E.; Burghaus, U.

doi:10.1016/j.cplett.2006.03.007

Cited by 24 publications

(14 citation statements)

References 25 publications

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“…The adsorption energies are estimated to be 0.50 and 0.76 eV, respectively with vertical and inclined configurations at BBO V , much larger than the value of 0.17 eV for the CO 2 on Ti 4+ site with the O-C-O bond parallel to [001] direction, in agreement to the previous TPD results that the CO 2 binds to the BBO V of Ti 3+ sites more strongly than to fivefold coordinated Ti 4+ sites. [25][26][27][28][29][30] However, our STM observations do not support recent reported results that the stable adsorption configuration of CO 2 presents at the Ti 4+ site. 31,32 We believe their observed bright protrusions at the Ti 4+ site measured at 80 K could be resulted from species other than adsorbed CO 2 molecules.…”

Section: contrasting

confidence: 99%

CO2dissociation activated through electron attachment on the reduced rutile TiO2(110)-1×1 surface

Tan

Zhao

et al. 2011

Phys. Rev. B

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Converting CO 2 to useful compounds through the solar photocatalytic reduction has been one of the most promising strategies for artificial carbon recycling. The highly relevant photocatalytic substrate for CO 2 conversion has been the popular TiO 2 surfaces. However, the lack of accurate fundamental parameters that determine the CO 2 reduction on TiO 2 has limited our ability to control these complicated photocatalysis processes. We have systematically studied the reduction of CO 2 at specific sites of the rutile TiO 2 (110)-11 surface using scanning tunneling microscopy at 80 K. The dissociation of CO 2 molecules is found to be activated by one electron attachment process and its energy threshold, corresponding to the CO 2  /CO 2 redox potential, is unambiguously determined to be 2.3 eV higher than the onset of the TiO 2 conduction band. The dissociation rate as a function of electron injection energy is also provided. Such information can be used as practical guidelines for the design of effective catalysts for CO 2 photoreduction.

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Section: contrasting

confidence: 99%

CO2dissociation activated through electron attachment on the reduced rutile TiO2(110)-1×1 surface

Tan

Zhao

et al. 2011

Phys. Rev. B

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“…1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 6 view) show the most energetically stable CO 2 adsorption configuration on the GaN(10 10) surface, which was derived based on detailed simulation studies (see Supplementary Info. 8,9,[27][28][29][30][31][32][33] , which inevitably lead to carrier loss, induce instability related issues, and become inactive with the adsorption of oxygen molecules.…”

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“…The first and foremost step for CO 2 reduction is the adsorption and deformation of the relatively inert CO 2 molecules on the photocatalyst surface. It has been well recognized that the adsorption of CO 2 on conventional metal oxide surfaces is dominated by defect sites (oxygen vacancies). , The oxygen vacancies, however, also enhance the adsorption of O 2 molecules, which can subsequently fill the vacancy sites and lead to an inactive surface. Moreover, metal oxide semiconductors generally exhibit a large band gap, which limits the absorption of the visible and infrared solar spectrum .…”

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“…The C–O bond can then be readily broken if the molecule is further excited by photogenerated electrons. For comparison, the adsorption of CO 2 on a conventional metal oxide surface is often dominated by the presence of defects (oxygen vacancies), ,,− which inevitably lead to carrier loss, induce instability related issues, and become inactive with the adsorption of oxygen molecules.…”

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Photochemical Carbon Dioxide Reduction on Mg-Doped Ga(In)N Nanowire Arrays under Visible Light Irradiation

et al. 2016

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The photochemical reduction of carbon dioxide (CO2) into energy-rich products can potentially address some of the critical challenges we face today, including energy resource shortages and greenhouse gas emissions. Our ab initio calculations show that CO2 molecules can be spontaneously activated on the clean nonpolar surfaces of wurtzite metal nitrides, for example, Ga(In)N. We have further demonstrated the photoreduction of CO2 into methanol (CH3OH) with sunlight as the only energy input. A conversion rate of CO2 into CH3OH (∼0.5 mmol gcat –1 h–1) is achieved under visible light illumination (>400 nm). Moreover, we have discovered that the photocatalytic activity for CO2 reduction can be drastically enhanced by incorporating a small amount of Mg dopant. The definitive role of Mg dopant in Ga(In)N, at both the atomic and device levels, has been identified. This study reveals the potential of III-nitride semiconductor nanostructures in solar-powered reduction of CO2 into hydrocarbon fuels.

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“…[1][2][3] Titanium dioxide has usually been the photocatalyst of choice and Degussa P25, which contains about 80% anatase and 20% rutile, has emerged as the benchmark material. 3 Photocatalysis studies have spanned well-characterized, single-crystal (usually rutile) surfaces under ultrahigh vacuum (UHV) conditions [4][5][6] to polycrystalline powders under catalysis operational conditions. [7][8][9] The latter have generally involved the catalyst in contact with an aqueous solution or water vapor.…”

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Apparent Semiconductor Type Reversal in Anatase TiO₂ Nanocrystalline Films

et al. 2007

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The electronic properties of anatase and rutile TiO 2 polycrystalline particle films have been studied using surface photovoltage (SPV) and infrared (IR) spectroscopies. The films were prepared from aqueous suspensions using a range of particle sizes (8-400 nm) and were examined under different ambient conditions. The results show that all of the examined films exhibited the expected n-type semiconductor characteristics in dry nitrogen ambient. Films created from the 30 and 400 nm anatase particles exhibited the largest surface photovoltage and also a broad mid-IR absorption attributed to shallowly trapped electrons. The latter was absent from films made from rutile particles. When examined under as-prepared "wet" conditions, the SPV was reduced in magnitude and the IR signal was absent. Further, the films formed from 8 and 30 nm particles exhibited an apparent p-type behavior in their SPV spectra. Interestingly, small anatase particles are known to exhibit enhanced photocatalytic activity when compared to larger anatase particles. These correlations indicate that water, adsorbed on TiO 2 particles of nanodimensions, induce surface states and enable redistribution of photogenerated charge carriers, which is conducive to photocatalysis.Photocatalysis at semiconductor surfaces has been extensively investigated over recent decades. 1-3 Titanium dioxide has usually been the photocatalyst of choice and Degussa P25, which contains about 80% anatase and 20% rutile, has emerged as the benchmark material. 3 Photocatalysis studies have spanned well-characterized, single-crystal (usually rutile) surfaces under ultrahigh vacuum (UHV) conditions 4-6 to polycrystalline powders under catalysis operational conditions. 7-9 The latter have generally involved the catalyst in contact with an aqueous solution or water vapor. It is acknowledged that the presence of water is important for photocatalysis, 10-11 but its exact role in the process is poorly understood. 12-15 Numerous models 13,[16][17][18][19] have been proposed for the influence of adsorbed water on charge carrier trapping but consensus has still to be reached.Surface photovoltage (SPV) spectroscopy has been used to study both polycrystalline and single crystal (110) rutile TiO 2 . [20][21][22] For both types of material, it was reported that water modified the surface work function of rutile TiO 2 surfaces. There appear to have been no corresponding studies of anatase TiO 2 surfaces. It has been observed that adsorbed water influences a broad mid-infrared spectral absorption between 4000 and 700 cm -1 , which arises when TiO 2 polycrystalline films are irradiated with UV light 13,17,23,24 and that has been assigned to excitation of shallowly trapped electrons. 24 Panyatov and Yates 17 observed that this signal decreases when water is chemisorbed to the surface of a thermally reduced P25 TiO 2 film. They propose that the water depletes conduction band electrons during the formation of Ti-OH groups in the early stages of chemisorption. In this paper, we report the results...

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Effect of oxygen vacancy sites on CO2 adsorption dynamics: The case of rutile (1×1)-TiO2 (110)

Cited by 24 publications

References 25 publications

CO2dissociation activated through electron attachment on the reduced rutile TiO2(110)-1×1 surface

CO2dissociation activated through electron attachment on the reduced rutile TiO2(110)-1×1 surface

Photochemical Carbon Dioxide Reduction on Mg-Doped Ga(In)N Nanowire Arrays under Visible Light Irradiation

Apparent Semiconductor Type Reversal in Anatase TiO₂ Nanocrystalline Films

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Effect of oxygen vacancy sites on CO2 adsorption dynamics: The case of rutile (1×1)-TiO2 (110)

Cited by 24 publications

References 25 publications

CO2dissociation activated through electron attachment on the reduced rutile TiO2(110)-1×1 surface

CO2dissociation activated through electron attachment on the reduced rutile TiO2(110)-1×1 surface

Photochemical Carbon Dioxide Reduction on Mg-Doped Ga(In)N Nanowire Arrays under Visible Light Irradiation

Apparent Semiconductor Type Reversal in Anatase TiO2 Nanocrystalline Films

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Apparent Semiconductor Type Reversal in Anatase TiO₂ Nanocrystalline Films