Ab initio study of electronic and optical properties of doped anatase (1 0 1) surface
Graphical abstract
Schematic model of atomic structures of anatase (1 0 1) surface: (a) pure case; (b) one atom is replaced by atom (red colour); (c) two atoms are replaced by atoms (red colour). atoms are represented by grey sphere, atoms by green sphere and atoms by red sphere.
Introduction
Titanium dioxide () is one of the most studied transition metal oxides. It occurs naturally in three most common polymorphic structures: rutile, anatase and brookite. The brookite structure is very rare and difficult to prepare by experimental methods [1], [2] so this phase is of lesser interest in applications. The bulk single crystal anatase is less stable than bulk rutile (rutile is denser than anatase), but is more efficient and more widely used in photocatalysis and photoelectrochemistry [3], [4], [5], owing to higher levels of surface area and thus higher activity [6]. In addition to these three phases, Zhu and Gao [7] and Zhi-Gang Mei and co-authors [8] investigated the properties of nine different polymorphs (rutile, anatase, brookite, columbite, baddeleyite, cotunnite, pyrite, fluorite and tridymite).
Because of its high efficiency and photostability is widely applied to the production of low cost solar cells [9], [10], [11], hydrogen and environment protection (water and air detoxification) [12], [13], [14], [15], [16], [17], [18]. The advantages of as a semiconductor material are long-term stability, excellent functionality, non-toxic environmental acceptability and low cost availability [2]. is a wide-gap semiconductor; and for anatase and rutile, respectively. This wide band gap is its major disadvantage, because it means that it is mainly activated by ultraviolent (UV) light and, consequently, it is inefficient as an active solar cell material. The gap between the valence and conduction bands and the optical absortion properties are the most important quantities for industrial applications. Many attempts have been made to narrow the band gap, and also, to increase the photoreactivity in the visible light region. Generally, dopants will change the physical and chemical properties, in whatever phase; rutile or anatase.
The electronic structure and optical properties of anatase and rutile have been investigated both experimentally [19], [20], [21], [22], [23], [24], [25], [26], [27], [28], [29] and theoretically [30], [31], [32], [33], [34], [35].
The investigation of the fundamental properties of are still very important because of their important role to effectively utilize solar energy [7]. Reducing the band gap has attracted much interest of researchers. A good method for this and to extend the spectral response of the to the visible light region is impurity doping. It has been noticed that doping with different metal and non-metal can improve the properties of material; may that doping lead to better synergistic effect, decrease the band gap and the recombination rate of the photo-generated electron-hole pairs [36], [37], [38], enhance the visible light absortion efficiently [39], [40]. There are number of papers regarding the narrowing the band gap by doping different elements in order to improve the photocatalytic activity of (see, for example, Refs. [41], [42], [43], [44], [45], [46], [47], [48], [49], [50], [51], [52], [53], [54], [55], [56], [57], [58], [59], [60], [61], [62], [63], [64], [65], [66]).
The complications with doping in order to reduce the band gap while maintaining the beneficial photocatalytic properties is noticed by Phattalung and coworkers [3]. To solve these problems it is necessary to understand, in detail, the changes resulting from the impurity. It is therefore desirable to study the properties of impurities.
In the last decade the research interest is mainly focused on adsorption of the surfaces [67], [68], [69], [70], [71], [72], [73], [74], [75]. In general, the anatase (1 0 1) surface is regarded to be most relevant to catalytic reactivity of [68]. The (1 0 1) surface is the predominant face that is exposed on anatase minerals, and theoretical calculations also show that it is thermodynamically the lowest-energy surface [76], [77]. Investigation of interface structures between surfaces and water [78] are performed by researchers, focusing on the adsorption manner of water molecules. The research of interface structures between surfaces and gas (for example and - mainly consistent of motor vehicle exhaust gas) are then continues by researchers [79], [80], [81], focusing on the adsorption manner of gas molecules. Researcher have found that light catalytic oxidation technology can effectively remove pollutants. Photocatalytic reactions at the surface have been attracting much attention of their applications to environmental cleaning; water and air purification. Because of strong oxidation activity and superhydrophilicity [82] can be used as antibacterial agent.
Doping of the surface layers may induce new features in the electronic structure and geometry of which are not present in the bulk.
In this paper we investigate the effects of -doping at the surface of on the electronic structure. It has been shown [69] that the presence of dopants at or near the surface is relevant for the activation of the redox-reaction processes. In general, the anatase (1 0 1) surface is regarded to be most relevant for catalytic reactivity of [68] and it plays a relevant role in the activation of photochemical processes [69].
Since the atoms are more stable in substitutional lattice positions (see Ref. [83]) for the entire range of Fermi energy over the band gap, only this substitutional position is considered.
One of our main motivations is to gain further insight into the electronic properties of anatase (1 0 1) surface by introducing dopants. This investigation has been done by means of density-functional theory (DFT) plane-wave pseudopotential method.
There are a number of papers regarding the properties of doped ; see, for example, Refs. [84], [85], [86], [87], but all these calculations have been done for the bulk structure.
The efficiency of photocatalytic activity of metal doped under visible light strongly depend on the dopant nature and concentration, as well as on the preparation methods and the thermal and reductive treatments [88], [89], [90], [91], [92], [93].
Yalcin and co-authors [85] investigated by DFT the influence of doping on electronic and structural properties of and found that the additional electronic state within the band gap is formed, and consequently, decrease the band gap. First-principles calculations were conduct in the case of co-doped [84], [85], [86]. Hsuan-Chung Wu and co-authors [87] performed first-principles calculations using GGA+Hubbard U (GGA+U) approach, but all these calculations considered the bulk structure. Yuan and co-authors [94] performed first-principle calculations using LSDA + U approach but for rutile (1 1 0) and (0 1 1) surfaces.
Section snippets
Computational details
The calculations were performed using plane-waves method based on the density functional theory (DFT), as implemented in the first-principles code, Spanish Initiative for Electronic Simulations of Thousands of Atoms (SIESTA) [95]. The exchange and correlation effects were calculated within the generalized gradient approximation (GGA) parametrized by Perdew, Burke and Ernzerhof (PBE) [96]. We used a double- basis set including polarization functions (DZP), with energy shift parameter of
Results
As it was already mentioned our calculated lattice parameters are in good agreement with the experimental and previous theoretical work. Also our calculated results for the enthalpy of formation Δ of per formula unit agree very well with the previous calculated per formula unit [100] and per molecular formula [3]. In the case of surface energy of anatase (1 0 1) surface our calculated result is ; which slightly differ from the previous calculation of
Conclusions
Based on the DFT calculations we have investigated the structure, electronic and optical properties of doped anatase (1 0 1) surface.
The effects of dopant on the stability of the anatase phase is predicted by the analysis of the enthalpy of formation, surface energy of anatase (1 0 1) surface, defect formation energy, Partial Density of State and absorption spectra in the region of visible light.
From the calculated results the following conclusion was drawn: due to the
Acknowledgments
This work was supported by the Serbian Ministry of Education, Science and Technological Development under Grants No. OI-171023, OI-171018 and OI-171001.
References (103)
- et al.
Ab initio calculations of electronic properties of pure and doped anatase
J. Mol. Struct: Theochem
(2005) - et al.
First-principles study of the mechanical properties and phase stability of TiO2
Comput. Mater. Sci.
(2014) - et al.
Evaluating the activities of immobilized TiO2 powder films for the photocatalytic degradation of organic contaminants in water
Appl. Catal. B: Environ.
(2004) - et al.
Immobilisation of TiO2 powder for the treatment of polluted water
Appl. Catal. B: Environ.
(1998) - et al.
Electronic structure of rutile (TiO2)
J. Phys. Chem. Solids
(1993) - et al.
Optical properties of N and transition metal R (R = V, Cr, Mn, Fe Co, Ni, Cu, and Zn) codoped anatase TiO2
Phys. B: Condens. Matter
(2012) - et al.
Origin of photocatalytic activity of W/N-codoped TiO2: H2 production and DFT calculation with GGA+U
Appl. Catal. B: Environ.
(2014) - et al.
Effect of Ce, N and S multi-doping on the photocatalytic activity of TiO2
Appl. Surf. Sci.
(2013) - et al.
Preparation of S-doped TiO2 photocatalysts and their photocatalytic activities under visible light
Appl. Catal. A: Gen.
(2004) - et al.
Low-temperature hydrothermal synthesis of S-doped TiO2 with visible light photocatalytic activity
J. Solid State Chem.
(2006)
Visible-light sensitization of TiO2 photocatalysts by wet-method N doping
Appl. Catal. A: Gen.
Origin of visible-light-driven photocatalysis: a comparative study on N/F-doped and N-F-codoped TiO2 powders by means of experimental characterizations and theoretical calculations
J. Solid State Chem.
Preparation and photocatalytic properties of composite CdS nanoparticles-titanium dioxide particles
J. Colloid Interface Sci.
Enhanced photocatalytic activity of nitrogen doped TiO2 photocatalysts sensitized by metallo Co, Ni-porphyrins
Appl. Surf. Sci.
One step synthesis of N-doped and Au-loaded TiO2 nanoparticles by laser pyrolysis: application in photocatalysis
Appl. Catal. B: Environ.
Promoting hydrogen production by loading PdO and Pt on N – TiO2 under visible light
Int. J. Hydrogen Energy
The electronic and magnetic structure of p-element (C, N) doped rutile-TiO2; a hybrid DFT study
Comput. Mater. Sci.
Electronic and optical properties of C and Nb co-doped anatase TiO2
Comput. Mater. Sci.
First principles study on electronic structures and properties of Sn-doped rutile TiO2
Comput. Mater. Sci.
First-principles calculations of a corrugated anatase TiO2 surface
Comput. Mater. Sci.
Formaldehyde on TiO2 anatase (101): a DFT study
Comput. Mater. Sci.
Adsorption and diffusion studies of an O adatom on TiO2 anatase surfaces with first principles calculations
Comput. Mater. Sci.
Insights into the adsorption of CH2BrF on anatase TiO2 (101) surface through DFT modelling
Comput. Mater. Sci.
First-principles study of TiO2 anatase (101) surfaces doped with N
Phys. B: Condens. Matter
Titanium dioxide photocatalysis: present situation and future approaches
C. R. Chimie
Preparation, photocatalytic performance and electronic structures of visible-light-driven Fe–N-codoped TiO2 nanoparticles
Mater. Chem. Phys.
Fe+3-doped TiO2: a combined experimental and computational approach to the evaluation of visible light activity
Appl. Catal. B: Environ.
Theoretical study on the electronic and optical properties of (N, Fe)-codoped anatase TiO2 photocatalyst
J. Alloys Comp.
Phenol decomposition using Mn+/TiO2 photocatalysts supported by the sol-gel technique on glass fibres
J. Photochem. Photobiol. A: Chem.
Photocatalytic degradation of chlorobenzoic isomers in aqueous suspensions of neat and modified titania
J. Photochem. Photobiol. A: Chem.
The influence of transition metal doping on the physical and photocatalytic properties of titania
J. Photochem. Photobiol. A: Chem.
Heterogeneous photocatalysis transition metal ions in photocatalytic systems
Appl. Catal. B: Environ.
Characterization of Fe–TiO2 photocatalysts synthesized by hydrothermal method and their photocatalytic reactivity for photodegradation of XRG dye diluted in water
J. Mol. Catal. A: Chem.
LSDA + U calculations of the electronic and optical properties of rutile TiO2 (110) vs (011) - 2 1 surfaces
Comput. Mater. Sci.
Structure and activity of nanosized iron-doped anatase TiO2 catalysts for phenol photocatalytic degradation
Appl. Catal. B: Environ.
Tailored preparation methods of TiO2 Anatase, Rutile, Brookite: mechanism of formation and electrochemical properties
Chem. Mater.
The electronic structure and optical response of rutile, anatase and brookite
J. Phys: Condens. Matter
First-principles study of native defects in anatase
Phys. Rev. B
Band alignment of rutile and anatase TiO2
Nat. Mater.
Comparison of the photoelectronic and photocatalytic activities of various anatase and rutile forms of titania in pure liquid organic phases and in aqueous solutions
J. Phys. Chem.
The stability, electronic structure, and optical property of TiO2 polymorphs
J. Phys. Chem. C
Solar energy conversion by dye-sensitized photovoltaic cells
Inorg. Chem.
Charge recombination in dye-sensitized nanocrystalline TiO2 solar cells
J. Phys. Chem. B
A low-cost, high-efficiency solar cell based on dye-sensitized colloidal TiO2 films
Nature
Electrochemical photolysis of water at a semiconductor electrode
Nature
Development of alternative photocatalysts to TiO2: challenges and opportunities
Energy Environ. Sci.
Photoelectrochemical cells
Nature
Bactericidal activity and water purification of immobilized TiO2 photocatalyst in bean sprout cultivation
Biotechnol. Lett.
Water purification by semiconductor photocatalysis
Chem. Soc. Rev.
Room-temperature ferromagnetism in transparent transition metal-doped titanium dioxide
Science
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