DE102006049769A1 - Photocatalytic yellow pigment, process and apparatus for its preparation - Google Patents

Abstract

Nitrogen-containing photocatalyst based on titanium dioxide has significant light absorption at wavelengths of at least 400 nm compared with pure titanium dioxide, has a strong absorbtion band at a binding energy of 399.1 eV in its x-ray photoelectron spectrum relative to the O1s band at 530 eV, and has an azo bond vibration at 1329 cm->1> in its infrared spectrum. Independent claims are also included for: (1) producing a nitrogen-containing titanium dioxide that is photoactive in visible light by mixing a titanium compound having a BET surface area of at least 50 m2>/g with a nitrogen compound and heat-treating the mixture at up to 400[deg] C; (2) depositing a photocatalyst as above as a thin film on a compact or porous support material, e.g. glass, wood, fibers, ceramic, concrete, building material, silica, metal, natural or suynthetic fabric, paper or plastic.

Description

The present invention relates to a nitrogen-containing photocatalyst based on titanium dioxide, which is photoactive in the visible region and has a core-shell structure. This novel material is also called TiO ₂ -NKS in the following.

The invention further relates to a process for producing a nitrogen-containing titanium dioxide (TiO ₂ -NKS) which is effective as a photocatalyst when irradiated with visible light.

The The invention also relates to a device for producing a nitrogen-containing Titanium dioxide with core-shell structure.

Photocatalytic Materials are semiconductors in which under the influence of light electron-hole pairs arise, the highly reactive on the material surface free radicals produce. Titanium dioxide is one such semiconductor. It is known, that titanium dioxide natural and artificial impurities in air and water by irradiation can remove with UV light, by reducing the oxygen in the air and making the pollutants environmentally friendly End products are oxidized (mineralized). Titanium dioxide is also known as Photoanode in photoelectrochemical cells for solar power generation used.

A serious disadvantage of titanium dioxide is the fact that it can only use the UV component of the sunlight, ie only 3 to 4% of the radiation, and is either not at all or only very weakly catalytically active in diffuse daylight. Attempts have therefore been made for a long time to modify titanium dioxide so that it can also use the majority of the photochemically effective sunlight - the visible spectral range of about 400 to about 700 nm - to generate the aforementioned phenomena. In photoelectrochemical cells, this is achieved inter alia by coating the titanium dioxide photoanode with a ruthenium bipyridyl complex (eg EP 1 473 745 A1 ). In systems for the degradation of pollutants in air and water with visible light, this is achieved, for example, by doping with metal ions such as V, Pt, Cr, Fe, etc. Another possibility is the generation of oxygen vacancies in the TiO ₂ crystal lattice by reduction of the Ti ^{4 +} . Also, by doping titanium dioxide with various carbon species, visible light activity can be obtained. These materials are characterized by a gray color ( JP 11333304 A . EP 0 997 191 A1 ). All previously known methods usually require complex production techniques such as ion implantation or plasma treatment.

Numerous patents describe nitrogen-modified titanium dioxide, which is photocatalytically active when irradiated in the visible range (eg EP 1 178 011 A1 . EP 1 174 392 A1 . EP 1 065 169 B1 and). In all publications, starting from a titanium salt or titanium alcoholate by hydrolysis with ammonia or one of its derivatives, first a nitrogen-containing titanium hydroxide is precipitated, which is then subsequently calcined at temperatures of 250-500 ° C. In EP 1 254 863 A1 a process is claimed in which titanium dioxide and / or titanium hydroxide with ammonia or one of its derivatives is heated to temperatures between 250-500 ° C.

In some publications, nitrogen-modified titanedioxide has been reported (a) Sato, Chem. Phys. Lett. 1986, 123, 126 ; b) R. Asahi, T. Morikawa, T. Ohwaki, A. Aoki, Y. Taga, Science 2001, 293, 269 ; c) T. Morikawa, R. Asahi, T. Ohwaki, A. Aoki, Y. Taga, Jpn. J. Appl. Phys. 2001, 40, 561 ; d) S. Sakthivel, H. Kisch, ChemPhysChem, 2003, 4, 487 ; e) T. Lindgren, JM Mwabora, E. Avendano, J. Jansson, A. Hoel, CG. Grangvist, SE. Lindquist, J. Phys. Chem. B 2003, 107, 5709 ; f) H. Irie, Y. Watanabe, K. Hashimoto, J. Phys. Chem. B 2003, 107, 5483 ; G) S. Sakthivel, M. Janczarek, H. Kisch, J. Phys. Chem. B 2004, 108, 19384 ; H) M. Miyauchi, A. Ikezawa, H. Tobimatsu, H. Irie, K. Hashimoto, PhysChemChemPhys, 2004, 6, 865 ; i) O. Diwald, TL Thomson, T. Zubkov, Ed. G. Goralski, SD Walck, JT Yates, J. Phys. Chem. B 2004, 108, 6004 ; j) D. Li, H. Haneda, S. Hishita, N. Ohashi, Mater. Sci. Engg. B, 2005, 117, 67 ; k) S. Livraghi, A. Votta, MC Paganini, E. Giamello, Chem. Commun. 2005, 498 ; I) Y. Nosaka, M. Matsushita, J. Nishino, AY Nosaka, Science and Technology of Advanced Materials 2005, 6, 143 , m) C. Burda, Y. Lou, X. Chen, ACS Samia, JD Stout, JL Gole, Nano Lett. 2003, 3, 1049 ; n) JL Gole, JD Stout, C. Burda, Y. Lou, X. Chen, J. Phys. Chem. B 2004, 108, 1230 ). The powders described therein and also in the patents (hereinafter also referred to as TiO ₂ -N) are distinguished by an absorption spectrum in which the steep band edge absorption begins at about 406 nm and from a weak pre-absorption reaching into the visible region up to about 550 nm flanked. In contrast, TiO ₂ -NKS has no weak preabsorption band, but the strong band edge absorption starts at 504 nm (see 1 and Table 1). This means much greater absorption of visible light, such as daylight, compared to the conventional TiO ₂ -N powders, and results in TiO ₂ -NKS having excellent photocatalytic properties when excited by visible light. Another difference to conventional TiO ₂ -N is that TiO ₂ -NKS according to the invention contains a hyponitrite species which in the infrared spectrum has a characteristic band at 1329 cm ^-1 (in KBr), while in TiO ₂ -N at 1387 cm ^-1 (in KBr). Accordingly, the N1s bonds also differ gies; they amount to 399.1 eV for TiO ₂ -NKS ( 2A ) and 396.0 to 396.7 eV for the already known TiO ₂ -N (based on the O1s band at 530 eV).

Of the Disadvantage of the known photocatalytic materials is that that the Process for their preparation not suitable for large-scale production are.

Of the Invention is based on the object photocatalytic with visible light highly active yellow pigment based on a nitrogen-modified Provide titanium dioxide and an economical process and to provide a device for its production.

According to the invention, the object is achieved by a nitrogen-containing titanium dioxide (TiO ₂ -NKS), which according to the invention has hyponitrite and a light absorption in the range of λ ≥ 400 nm that is significant compared to pure titanium oxide. Compared to previously known nitrogen-containing titanium dioxides, the new material differs in that it has a only several nanometers thin shell of hyponitritdotiertem Titandioixd and a core of unmodified titanium dioxide (core-shell particles). The differences are documented according to the invention by infrared and diffuse reflection spectrum and the binding energy of the N1s electrons.

The Task is further solved by a manufacturing method, in the titanium hydroxide with an inorganic or organic nitrogen compound in aqueous suspension is intimately mixed and the resulting powder after washing and drying at a temperature of up to 400 ° C thermally in a rotary kiln is treated.

Further advantageous embodiments of the invention are specified in the subclaims

product

The TiO ₂ -NKS according to the invention exhibits a higher photocatalytic activity than the types described in the prior art. As a measure of the photocatalytic activity (hereinafter referred to as "photoactivity") is the degradation of 4-chlorophenol by a defined amount of TiO ₂ -NKS with 360-minute irradiation with light of wavelength ≥ 420 nm. The measuring method is described in detail below. Under the measurement conditions mentioned, the photoactivity of the TiO ₂ -NKS according to the invention is at least 40%, preferably at least 60%, in particular at least 70% ( 5 ). The outstanding activity of TiO ₂ -NKS is also documented in the decomposition of formic acid. While TiO ₂ -N is inactive, TiO ₂ -NKS induces a degradation of more than 60% ( 6 ).

The nitrogen content is from 0.5 to 10 wt .-% based on TiO ₂ , preferably 0.1 to 3.0 wt .-% and particularly preferably 0.09 to 2.0 wt .-%. Best results are achieved at nitrogen contents of 0.09 to 1.1 wt%. The titanium dioxide particles TiO ₂ -NKS are characterized in that they contain nitrogen only in a surface layer (shell), while the core consists of unmodified titanium dioxide. The approximately 3 to 10 nm thin shell is characterized in that nitrogen is thought to be present as cis-hyponitrite (N ₂ O ₂ ^2- ), as shown by the location of the ☐ (N = N) valence vibration at 1329 cm ^-1 (KBr) and the N1s binding energy of 399.1 eV (based on the O1s band at 530 eV) measured by means of X-ray photoelectron spectroscopy (XPS). In contrast, these values in the already known TiO ₂ -N are 1387 cm ^-1 and 396.0-396.7 eV, respectively. The hyponitrite of the TiO ₂ -NKS according to the invention is believed to be primarily covalently bound to titanium atoms via the oxygen atoms in a chelate manner.

Of the new photocatalyst allows Pollutant degradation with visible light. He can therefore break down of impurities and pollutants in liquids or gases, in particular in water and air.

The photocatalyst can be advantageously applied to various compact or porous supports such as glass (normal and mirrored), wood, fibers, ceramics, concrete, building materials, SiO ₂ , metals, natural and artificial fabric, paper and plastics as a thin layer. Together with the simple production, this opens up application possibilities in a variety of areas, such as in the construction, ceramics and vehicle industries for self-cleaning surfaces or in environmental technology (air conditioning units, devices for air purification and air sterilization and water purification, especially drinking water).

Of the Photocatalyst can be used in coatings for indoor and outdoor use such as. Paints, plasters, lacquers and glazes for masonry applications, Plaster surfaces, Paintings, wallpaper and wood, metal, glass or ceramic surfaces or on components such as thermal insulation systems and curtain wall elements Find employment, as well as in road coverings and in plastics, fibers and paper. In addition, the photocatalyst can in the production of precast concrete products, roofing tiles, ceramics, Tiles, wallpapers, fabrics, panels and coverings for ceilings and walls indoors and outdoors be used. As interior are in this context too especially illuminated street underpasses (e.g., highway tunnels).

The photocatalyst is particularly suitable for use in photovoltaic cells. In this case, TiO ₂ -NKS is applied in a thin layer on a conductive glass plate, such as indium-tin-doped glass, and dipped together with a metallic counter electrode in a redox electrolyte, for example iodine / iodide. Upon exposure of the TiO ₂ -NKS electrode, an electrical voltage occurs between the two electrodes.

The TiO ₂ -NKS according to the invention is described below with reference to 1 to 7 described in more detail.

1A shows the absorbance for unmodified TiO ₂ (curve a), for the already known nitrogen-doped TiO ₂ -N (curve b) and for the core-shell material TiO ₂ -NKS (curve c) as a function of the wavelength and indicates that unlike unmodified titanium dioxide and TiO ₂ -N, the TiO ₂ -NKS has a steep band edge absorption in the visible spectral region. The Kubelka-Munk function F (R _∞ ) is proportional to the absorbance. 1B shows the off 1A derived plot of the modified Kubelka-Munk function as a function of the light energy. From the intersection of the linear curve drop with the abscissa results in the band gap.

2A contains the X-ray photoelectron spectrum (XPS) of the TiO ₂ -NKS according to the invention before (curve a ₁ ) and after two minutes sputtering with argon ions; This corresponds to the removal of an approximately 3-4 nm thick surface layer (curve a ₂ ).

2 B shows the powder diffractogram of TiO ₂ -NKS; (*) Anatas, (+) brookite. The calculated by the Scherrer method crystallite size is 10 nm. The determined according to the Brunnauer-Emmet plate (BET) specific surface area is 170 m ² / g.

3 shows the variation of the photovoltage depending on the pH. From the inflection point, the quasi-Fermi level of the electrons ( _n E _F *) can be obtained (according to the method of AM Roy, GC De, N. Sasmal, SS Bhattacharyya, Int. J. Hydrogen Energy 1995, 20, 627 ). For TiO _{2 it} is -0.63 V (curve a), for TiO ₂ -NKS it is -0.56 V (curve b) and for unmodified TiO _{2 it} is -0.47 V (table 1).

4 summarizes the band edges determined from the quasi-Fermi energy and the band gap as well as those from the absorption beginning ( 1A ) taken together position of the surface states (hatched area) together. All potentials apply to pH 7 and are based on the normal hydrogen electrode. (a) TiO ₂ , (b) TiO ₂ -N, (c) TiO ₂ -NKS.

5 shows the photoineralization of 4-chlorophenol (c = 2.5 × 10 ^-4 mol L ^-1 , TOC ₀ and TOC _t = total organic carbon content of the reaction solution at times 0 and t minutes, λ ≥ 420 nm; (a) TiO ₂ , (b) TiO ₂ -N, (c) TiO ₂ -NKS.

6 describes the photomineralization of some pollutants in the presence of TiO ₂ -NKS, λ ≥ 420 nm; (a) hydroquinone (2.5 x 10 ^-4 mol L ^-1 ), (b) formic acid (1 x 10 ^-3 mol L ^-1 ), (c) trichlorethylene (2.5 x 10 ^-4 mol L ^-1 ); (d) Photomineralization of formic acid (1 × 10 ^-3 mol L ^-1 ) in the presence of TiO ₂ -N. Comparison of curves b and d illustrates the highly effective photoactivity of TiO ₂ -NKS compared to TiO ₂ .

7 summarizes the decomposition of acetaldehyde (a, 5 vol .-%), benzene (b, 5 vol .-%) and carbon monoxide (c, 5 vol .-%) in the presence of TiO ₂ -NKS together; λ ≥ 420 nm. The reaction vessel used was a 100 ml glass cylinder equipped with a 9 × 2.5 cm silica gel-coated glass plate to which 50 mg TiO ₂ NKS had been applied. The decrease in the concentration of pollutants and the formation of carbon dioxide were monitored by infrared spectroscopy.

8th shows the measured under N ₂ atmosphere action spectrum of the photocurrent of a photoelectrochemical cell consisting of a coated with TiO ₂ -NKS indium tin oxide glass electrode, a platinum counter electrode and an Ag / AgCl (3 mol L ^-1 KCl) reference electrode; 0.1 mol L ^-1 LiClO ₄ and Kl / Kl ₃ . IPCE: the incident photon to current efficiency based on the intensity of the incident light; these are minimum values because losses due to scattering and reflection have not been taken into account.

manufacturing

The inventive method is based on a titanium compound in the form of an amorphous, semi-crystalline or crystalline titanium hydroxide and / or a Titanium hydrate and / or titanium oxyhydrate is present and in the following is referred to as the starting titanium compound.

The For example, starting titanium compound can be used in titanium dioxide production either by the sulphate process or by the chloride process be generated. Titanium hydrate or titanium oxyhydrate or metatitanic acid is e.g. precipitated in the hydrolysis of titanyl sulfate or titanyl chloride.

The starting titanium compound can be present as a fine-grained solid or in suspension with a corresponding solids content of at least 15% by weight, the specific surface area of the solid being at least 50 m ² / g according to BET, preferably about 150 to 250 m ² / g according to BET.

The Inorganic or organic nitrogen compound has a decomposition temperature from at most 400 ° C, better <200 ° C, preferably <300 ° C. As suitable especially ammonium salts and urea have been found.

The starting titanium compound is intimately mixed with the nitrogen compound in such a manner as to surface-coat the starting titanium compound with the nitrogen compound. The optionally pre-dried mixture is thermally treated at temperatures of at most 400 ° C. This results in the decomposition of the nitrogen compound on the surface of the starting titanium compound. The progress of the reaction can be monitored by measuring the diffuse reflectance spectra. The thermal treatment is discontinued when the Kubelka-Munk function at 450 nm falls below 20% of the value at 300 nm. Depending on the nature of the nitrogen compound used, it is advantageous to rid the resulting powder by washing with water of undesirable decomposition products. The thermal treatment is preferably carried out so that a product (TiO ₂ -NKS) having a nitrogen content of 0.5 to 10 wt .-% based on TiO ₂ , preferably 0.1 to 3.0 wt .-% and particularly preferably at 0.09 to 2.0 wt .-% arises. Best results are obtained at nitrogen contents 0.09 to 1.1 wt .-%.

The end product is characterized by a deep yellow color. It is characterized by containing a shell of nitrogen-doped titanium dioxide and a core of pure titanium dioxide. The BET specific surface area is 100 to 250 m ² / g, preferably 150 to 190 m ² / g. The TiO ₂ -NKS according to the invention enables pollutant degradation and photoelectrochemical power generation with visible light.

Examples

The Invention will be described in more detail with reference to the following examples, without thereby the Limited scope of the invention shall be.

Example 1:

A aqueous suspension of 3 g of titanium hydroxide in 50 ml of water is mixed with 1.5 g of urea and stirred magnetically at room temperature for 1 h. After removing the water in vacuo at 60 ° C becomes the backlog Dried for 30 min in a laboratory drying oven at 100 ° C. 1 g of the resulting Powder is treated in air in a 15 mL Schlenk tube for 1 h at 400 ° C. The resulting deep yellow powder is distilled three times Washed water and at 70 ° C dried.

Example 2:

analog Procedure as in Example 1 with the difference that instead Titanium hydroxide is used a titanium oxide hydrate.

Example 3

analog Procedure as in Example 1 with the difference that instead Titanium hydroxide titanium oxyhydrate is used.

Example 4:

Action as in Examples 1-3 with the difference that instead Urea an inorganic compound, preferably an ammonium salt is used.

Example 5:

Action as in Examples 1-3 with the difference that instead Urea an organic ammonium salt is used.

Example 6:

Action as in Examples 1-3 with the difference that instead Urea used another organic nitrogen compound is in the nitrogen in an oxidation state of -III to +1 is present.

Example 7:

For coating a plastic film, a powder prepared according to Examples 1-6 is suspended in an ultrasonic bath in a liquid such as water, methanol or ethanol, and the resulting suspension is applied as thin as possible to the film by means of a spray bottle. After subsequent drying at 70 ° C, the coating can be repeated until reaching the desired layer thickness. Instead of the plastic film, another carrier such as paper (see experiment according to 7 ) or a metal such as aluminum may be used.

Example 8

An indium tin oxide glass flake (2.5 x 1.5 cm) is washed with acetone, etched for one minute in boiling 0.1 mol L- ¹ NaOH and dried after washing with water in a stream of nitrogen. Subsequently, 0.1 ml of a suspension of 5 mg of TiO ₂ -NKS in 0.4 ml of water are applied to the platelet and the electrode thus coated is dried with warm air. After contacting with a copper wire and insulating the uncoated parts, eg with Parafilm, the TiO ₂ -NKS electrode is ready for use (see 8th ).

measurement methods

a) Determination of photoactivity (pollutant degradation) with visible light:

15 mg of the TiO ₂ -NKS are dispersed in 15 mL of a 2.5 × 10 ^-4 molar solution of 4-chlorophenol for 10 minutes in an ultrasonic bath and then exposed in a water-cooled round cuvette on an optical bench (lamp housing AMKO Mod. A1020, focal length 30 cm, Osram XBO 150 W xenon short arc lamp). The reactions are carried out in a 15 mL, water-cooled round cuvette with an inner diameter of 3 cm and a layer thickness of 2 cm. The reaction suspension is stirred with a side-mounted stirring motor and stirring magnet. To eliminate UV light, a Kant filter (Schott company) whose permeability is λ ≥ 420 nm is introduced into the beam path. To prevent heating of the reaction space by the exposure, an IR filter is mounted in the beam path. It consists of a water-filled cylinder (diameter 6 cm, length 10 cm).

The Decrease in the concentration of 4-chlorophenol is determined by UV spectroscopy (λ = 224 nm) or, in the case of degradation (mineralization), by measuring the total content followed by organic carbon (TOC value).

Degradation of acetaldehyde gas, benzene vapor and carbon monoxide:

3 ml of a suspension of 50 mg of TiO ₂ -NKS are applied to a glass plate coated with silica gel (9 × 2.5 cm, diatomaceous earth F 254 Merck) and dried in air overnight at room temperature. The photocatalyst plate thus obtained is exposed in a 100 ml glass flask under air-saturated acetaldehyde gas (5 vol.%) Or benzene vapor (5 vol.%) Or carbon monoxide (5 vol.%) On the optical bench. The decrease in the concentration of pollutants and the formation of carbon dioxide were monitored by IR spectroscopy.

b) Determination of the total carbon content

The Determination as total organic carbon content (TOC) with the carbon analyzer Shimadzu Total Carbon Analyzer TOC-500/5050.

c) XPS measurements

to Measurement of binding energies was the device Phi 5600 ESCA spectrometer (pass energy of 23.50 eV, Al standard, 300.0 W, 45.0 °) used.

Claims (28)

Nitrogen-containing photocatalyst based on titanium dioxide with a significant compared to pure titanium dioxide light absorption in the range of λ ≥ 400 nm, characterized by a strong absorption band at a binding energy of 399.1 eV in the X-ray photoelectron spectrum (XPS) based on the O1s band at 530 eV and by an N = N stretching vibration at 1329 cm ^-1 (in KBr) in the infrared spectrum. Nitrogen-containing photocatalyst according to claim 1, characterized in that the nitrogen is present as hyponitrite. Nitrogen-containing photocatalyst based on titanium dioxide with a significant compared to pure titanium dioxide light absorption in the range of λ ≥ 400 nm characterized by a steep rising absorption edge at 500 nm and by an absorbance (Kubelka-Munk function F (R _∞ ), which at 450 nm at least 20% of the absorbance at 300 nm. Nitrogen-containing photocatalyst on the base of titanium dioxide with one opposite pure titanium dioxide marked significant light absorption in the range of λ ≥ 400 nm through a photoactivity of at least 40% preferably at least 60% and in particular at least 70%. Photocatalyst according to one or more of claims 1 to 4, characterized in that its nitrogen content in the range of 0.5 to 10 wt .-% based on TiO ₂ , preferably 0.1 to 3.0 wt .-% and particularly preferably at 0.09 to 2.0 wt .-% is. Photocatalyst according to one or more of claims 1 to 5, characterized in that the nitrogen only in one a few nanometers thin surface layer the titanium dioxide particle is embedded (core-shell structure). Photocatalyst according to one or more of Claims 1 to 6, characterized in that the BET specific surface area is from 100 to 250 m ² / g, preferably from 150 to 190 m ² / g. A process for the preparation of a nitrogen-containing visible light photoactive titanium dioxide, characterized in that a titanium compound having a specific surface area of at least 50 m ² / g BET, intimately mixed with an inorganic or organic nitrogen compound and the mixture at a temperature of up to 400 ° C is thermally treated. A method according to claim 8 characterized gekenn indicates that the titanium compound is an amorphous, partially crystalline or crystalline titanium hydroxide, a titanium hydrate or a titanium oxyhydrate. Method according to one or more of claims 8 and 9 characterized in that the nitrogen-containing Substance has a decomposition temperature of at most 400 ° C, preferably <350 ° C. and particularly preferably <300 ° C. Method according to one or more of claims 9 and 10 characterized in that the nitrogen-containing Substance is a nitrogen compound which is at least one functional Group contains. Method according to claims 8 to 11, characterized that the functional group is one of the following groups: CO, COOH, Cl, Br. Process according to claims 8-12 characterized that as Nitrogen compound is a compound from the group ureas, Amides, amino acids or mixtures thereof. Method according to one or more of claims 8 to 13, characterized in that the nitrogen-containing Substance is hydrazine or hydroxylamine. Method according to one or more of claims 8 to 14 characterized in that the thermal Treatment in a device to be operated continuously, is preferably carried out in a rotary kiln. Method according to one or more of claims 8 to 15 characterized by the method steps: (a) Use a buyer Titanhydroxids, titanium hydrate or titanium oxyhydrate. (b) Suspend this titanium hydroxide compound in a solvent, (c) Add a nitrogenous substance to this suspension and mixing this substance with the suspension, (d) removing the solvent, (E) Dry the residue at a drying temperature and (f) calcining the residue at a calcination temperature. Method according to one or more of claims 8 to 16 characterized in that the solvent Water is. Method according to one or more of claims 8 to 17 characterized in that the calcination is carried out in a rotary kiln. Method according to one or more of claims 8 to 18 characterized in that the calcination of the powdery residue by heating takes place until after a color change of know yellow no further deepening of the yellow color increases. Applying the photocatalyst according to one or more of claims 1-19 on a compact or porous support material such as glass (normal and mirrored), wood, fibers, ceramics, concrete, building materials, SiO ₂ , metals, natural and artificial tissue, paper and plastics as thin layer. Use of the photocatalyst after one or several of the claims 1 to 20 in coatings, plastics, fibers and paper. Use of the photocatalyst after one or several of the claims 1 to 21 in paints, plasters and varnishes and / or glazes and / or on Masonry, precast concrete elements, plaster surfaces, tiles, ceramics, fabrics, Panels, paintings, wallpaper, wood, metal, glass and / or ceramic surfaces and / or Thermal insulation systems and / or curtains Facade elements in the interior and exterior of buildings and / or other structures, inside and / or outside of automobiles and / or other means of transport. Use of the photocatalyst after one or several of the claims 1 to 22 in the air and water purification. Use of the photocatalyst after one or several of the claims 1 to 23 for air purification in road tunnels. Use of the photocatalyst after one or several of the claims 1 to 24 in photovoltaic cells and / or photoelectrochemical cells. Use of the photocatalyst after one or several of the claims 1 to 25 in air conditioners and / or air sterilization for air purification. Use of the photocatalyst after one or several of the claims 1 to 26 in the drinking water purification. Use of the photocatalyst after one or several of the claims 1 to 27 in the construction, ceramics and vehicle industry and / or for self-cleaning surfaces or in environmental technology.