Oxygen adsorption on anatase surfaces and edges

Zhang, Li; Ji, Hefei; Lei, Yinkai; Xiao, Wei

doi:10.1016/j.apsusc.2011.04.091

Cited by 11 publications

(5 citation statements)

References 47 publications

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“…As shown previously, O 2 does not adsorb to a perfect, neutral TiO 2 surface. ,,, Our calculations also show that when O 2 is placed on the TiO 2 surface it relaxes into the vacuum rather than adsorbing. However, upon addition of one electron to simulate O 2 interacting with a photoexcited electron in TiO 2 , O 2 gains electron density provided by the additional electron and chemisorbs to the surface with an adsorption energy of −0.95 eV.…”

Section: Resultssupporting

confidence: 85%

“…Anatase is the major crystalline phase present in P25 TiO 2 powders and possesses the highest photoactivity among the three TiO 2 crystal structures (anatase, rutile, and brookite); the (101) face is the most stable and abundant anatase surface. , As a baseline for comparison with the effects of Pt, we first investigated electron scavenging from TiO 2 through O 2 adsorption and related electronic rearrangement processes. O 2 is well-known to not adsorb to neutral, perfect TiO 2 surfaces ,, while the negatively charged surface , and defects, such as O subsurface vacancies or Ti interstitials, are reported to facilitate the adsorption of O 2 . Aschuer et al’s pioneering work provides important insight into the interactions between the TiO 2 surface and O 2 and serves as the starting point for the portion of this study that describes the electronic distribution of charge upon O 2 adsorption and the mechanism by which O 2 scavenges excited electrons from the photoexcited TiO 2 surface.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Surface Deposited Pt on the Photoactivity of TiO₂

et al. 2012

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The roles of deposited Pt clusters and adsorbed O2 in the photoactivity of anatase TiO2 (101) surfaces have been studied using density functional theory. O2 only adsorbs to TiO2 surfaces when excess negative charge is available to form O–Ti bonds, which can be provided by a photoexcited electron or subsurface oxygen vacancy, in which cases the adsorption energies are −0.94 and −2.52 eV, respectively. When O2 adsorbs near a subsurface defect, it scavenges extra electron density and creates a hole that can annihilate excited electrons. In aqueous solutions, O2 interactions with the TiO2 surface are rare because water preferentially adsorbs at the surface. Pt clusters on TiO2 significantly enhance O2 adsorption providing many adsorption sites with adsorption energies up to −1.69 eV, stronger than the −0.52 eV adsorption energy of H2O on the Pt cluster. Consequently, Pt increases the rate of electron scavenging by O2 relative to that of undoped TiO2 leading to enhanced photocatalytic performance. Pt states completely bridge the band gap and act as electron–hole recombination centers, which are deleterious to the photoactivity of TiO2. The initial rise and subsequent fall in TiO2’s photoactivity with Pt loading results from the competition between enhanced electron scavenging due to increased O2 adsorption and increased electron–hole recombination.

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Section: Resultssupporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Effect of Surface Deposited Pt on the Photoactivity of TiO₂

et al. 2012

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“…During the geometry optimizations, the atoms in the bottom layer were fixed to their bulk positions to simulate the presence of the bulk underneath and others were free to relax until the computations reached the desired convergence standard [2]. Finally, as the ground state of the oxygen molecule is triplet [17], so we carried out the spin-polarized calculations for the adsorption of O 2 on the anatase surface.…”

Section: Theories and Methodsmentioning

confidence: 99%

Ab initio atomic thermodynamics investigation on oxygen defects in the anatase TiO2

Cheng

Liu

Yang

et al. 2013

Journal of Alloys and Compounds

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In the framework of the ab initio Atomic Thermodynamics, the preliminary analysis of the annealing mechanisms of the oxygen defects in anatase TiO 2 has been done by investigating the influence of the annealing treatment under representative conditions on three typical oxygen defects, that is, oxygen vacancy, oxygen adsorption and oxygen interstitial, all of which exist during the annealing treatment by the defect chemistry, therefore, should be explored independently. Our results in this study agree well with the related experiments findings including the recent discoveries, e.g., we find that the type of the molecular ion of the adsorbed O 2 can also be determined by the initial orientation of O 2 relative to the surface (101). However, the critical annealing conditions under which the dominant oxygen defects would begin to convert to another one have not been found out due to the drawback of the current research scheme and we propose that this flaw could be compensated by studying the kinetics of the reactions, which may be the major task in the next stage of this research.

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“…The latest calculation studies about the oxygen adsorption on anatase surfaces indicated that {001} facet can adsorb more oxygen molecules hindering the electron-hole recombination more efficiently and finally enhancing the efficiency of oxidation of adsorbed organic molecules. The facets-role assignment (oxidation or reduction) is not 6th Forum on New Materials -Part A clear because in case of OAPs {101} facets play rather the role of both oxidation and reduction sites [26][27][28]. Photocatalytic activities of silver modified OAPs and DAPs under UV and/or visible light irradiation are shown in Fig.…”

Section: Improvement Of Photocatalytic Activitymentioning

confidence: 99%

Development of Plasmonic Photocatalysts for Environmental Application

Kowalska

Wei

Karabiyik

et al. 2014

Advances in Science and Technology

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Regarding catalytic and plasmonic properties of gold nanoparticles (NPs), the novel area of research on photocatalytic gold properties has been recently started. In contrast with catalytically active gold NPs, where nanosized gold is recommended, our results showed that polydispersity of deposited gold NPs on semiconducting support was beneficial for photocatalytic activity under visible light irradiation. It is thought that wide size/shape distribution of gold NPs, and thus the ability of absorption of light in a wide wavelengths range is responsible for the high level of photoactivity. Though desirable absorption properties of plasmonic photocatalysts can be easily obtained by preparation of nanoparticles of different sizes and shapes, their photocatalytic activities under visible light irradiation are still low and should be enanced. The improvement of photocatalytic activities under visible light irradiation was achieved by enlargement of interfacial contact between titania and NPs of noble metals, extension of photoabsorption ranges (by preparation of NPs of various sizes and shapes or composed of two kinds of noble metals), and by deposition of noble metals NPs on faceted titania, i.e., octahedral (OAPs) and decahedral (DAPs). Plasmonic photocatalysts composed of titania and NPs of silver, gold or copper showed also high antiseptic properties under visible light irradiation, due to possible synergism of antiseptic properties of noble metals and photodisinfection properties of photocatalyst, since reactive oxygen species or photogenerated holes are formed on the surface of irradiated semiconductor.

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Oxygen adsorption on anatase surfaces and edges

Cited by 11 publications

References 47 publications

Effect of Surface Deposited Pt on the Photoactivity of TiO₂

Effect of Surface Deposited Pt on the Photoactivity of TiO₂

Ab initio atomic thermodynamics investigation on oxygen defects in the anatase TiO2

Development of Plasmonic Photocatalysts for Environmental Application

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Oxygen adsorption on anatase surfaces and edges

Cited by 11 publications

References 47 publications

Effect of Surface Deposited Pt on the Photoactivity of TiO2

Effect of Surface Deposited Pt on the Photoactivity of TiO2

Ab initio atomic thermodynamics investigation on oxygen defects in the anatase TiO2

Development of Plasmonic Photocatalysts for Environmental Application

Contact Info

Product

Resources

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Effect of Surface Deposited Pt on the Photoactivity of TiO₂

Effect of Surface Deposited Pt on the Photoactivity of TiO₂