Photocatalytic and thermal control glazing

Abstract

A glass article comprising a photocatalytic coating including a titanium nitride layer and an outer titanium oxide layer, preferably at least partially in anatase form, said article being configured to impart a blue colour in transmission to a multiple glazing unit in which it constitutes the outer face, said multiple glazing unit further comprising a low-emissivity coating on another face of said multiple glazing unit, in particular face 2 or 3.

Description

[0001] DESCRIPTION

[0002] TITLE Photocatalytic and thermal control glazing

[0003] The invention relates to the field of glass articles comprising a glass substrate coated with a photocatalytic layer and also exhibiting thermal insulation properties.

[0004] Photocatalytic coatings, particularly those based on titanium dioxide, preferably in its anatase form, are known to impart self-cleaning and antifouling properties to the substrates they coat. Two properties underlie these advantageous characteristics. First, titanium dioxide is photocatalytic, especially in its anatase form, meaning that under appropriate radiation, generally ultraviolet radiation, it can catalyze the degradation reactions of organic compounds. This photocatalytic activity is initiated within the coating by the creation of an electron-hole pair. Furthermore, titanium dioxide exhibits extremely high hydrophilicity when irradiated by this same type of radiation. This strong hydrophilicity allows mineral soiling to be washed away by water runoff, such as rainwater.Such glass articles, in particular glazing, are described for example in application EP-A-0 850 204.

[0005] The invention seeks to develop glazing that combines self-cleaning and anti-fouling properties with thermal control properties. Thermal control refers to the ability to reduce the amount of solar or thermal infrared radiation that can pass through the glazing and either heat the rooms of dwellings (or vehicle interiors) due to solar radiation in summer, or alternatively, prevent heat from escaping these same dwellings in winter. Glazing with such properties prevents excessive heating of the aforementioned rooms (or interiors) and, where applicable, limits energy consumption related to air conditioning in summer and reduces energy consumption in winter.

[0006] It is known from application WO 03 / 050056 that photocatalytic coatings are deposited on tinted glass. However, tinted glass exhibits low selectivity, which corresponds to the ratio between visible light transmission and energy transmission.

[0007] To solve this problem, patent application W02011 / 030049 describes glazing that combines thermal control and antifouling properties on the same surface. More specifically, the publication teaches how to combine, within the same stack, a niobium or niobium nitride-based layer and a titanium oxide layer comprising the photocatalytic anatase phase, with the titanium oxide layer being the top layer of the stack.

[0008] Publication WO2021 / 123681 proposes replacing the niobium-based thermal control layer with a titanium nitride (TiN)-based layer to address condensation issues associated with niobium-based coatings. However, the thermal control properties, particularly thermal insulation, of such layers are limited, especially for use in countries where outside temperatures can drop below 5°C, or even below 0°C during winter.

[0009] According to another aspect of the present invention, a blue transmittance color, considered aesthetically pleasing, is desired for certain markets. To obtain such a color, it is usually necessary to use glass that is itself blue in transmittance throughout its mass, which implies a significant final cost for the glazing. The object of the present invention is to provide a glass article comprising a colored stack that directly enables the blue transmittance color when deposited on clear glass. In particular, the invention aims to achieve a blue transmittance color for a multi-pane glazing unit comprising said glass article and another low-emissivity stack, arranged in combination on another face of the multi-pane glazing unit.

[0010] In particular, with a view to further improving the thermal insulation of buildings, the present invention proposes combining, within a multi-glazing unit, preferably a double-glazed unit (often called a DGU for "Double Glazing Unit" in the field), a photocatalytic coating on one surface and a thermal control coating on another surface, which may be the opposite surface of the same glass substrate or, more advantageously, the surface of the second glass substrate facing it. This thermal control coating, as is well known in the field of thermal control glazing, is advantageously composed of a stack of layers, at least one of which is silver, known to reflect solar or thermal infrared radiation. Such a stack is often called a low-emissivity or low-e stack in the field.

[0011] It is well known that stacked low-emissivity thermal control layers exhibit solar infrared reflectivity, primarily due to the presence of at least one silver-based or silver-alloy metallic functional layer, and possibly multiple such metallic layers, for example, two or three silver layers. Infrared reflectivity means that at least a portion of solar or thermal infrared radiation, preferably the majority, is reflected by the stack via its silver-based functional layer(s), without excluding the possibility that some absorption by the same layer.

[0012] The silver-based or silver-based layer(s), according to well-known technologies, are surrounded and separated by layers of dielectric materials, most often chosen from silicon oxide or nitride, titanium oxide, zinc oxide, tin oxide, tin and zinc oxide.

[0013] Examples of multiple glazings equipped with such silver layers are described for example in publications WO 2007 / 101964, EP877005, EP718250, FR2856627, EP 847965, EP 183052, EP226993, EP2920126, EP2766318, EP1441996, EP2432745, EP2424823, EP2332891, EP1730088, EP1663887, EP1606225, EP3041676, US10556824, EP1458653 or EP3004012 or W02010 / 103224.

[0014] Silver coatings have the disadvantage of poor climate durability. A multi-pane glazing arrangement in which the thermal control coating is located on surface 2 or surface 3, i.e., within the internal cavity of the glazing, provides protection from the outside, while the photocatalytic coating is positioned according to the invention on surface 1, i.e., on the exterior of the building, where it is most beneficial. This allows for glazing with both self-cleaning properties and enhanced infrared reflectivity (thermal control). However, it has become apparent that the presence of these two coatings leads to difficulties in achieving the blue color transmission currently sought in the market and described above.

[0015] The aim of the invention is therefore to provide glazing exhibiting both photocatalytic and thermal control properties, and whose colorimetry is adapted, in particular blue in transmission. Specifically, the object of the present invention is to provide multi-layered glazing comprising clear glass substrates, blue in transmission, and comprising on its outer face a stack exhibiting photocatalytic properties and a low-emissivity stack on another face of said glazing.

[0016] According to a first aspect, the invention relates first of all to a glass article comprising a glass substrate coated on at least one of its faces with a stack of layers comprising, preferably consisting of, from the surface of said substrate, a first SiNi layer comprising silicon nitride of thickness between 1 nm and 60 nm, a first titanium oxide layer of thickness between 8 nm and 55 nm, a second SiN2 layer comprising silicon nitride of thickness between 1 nm and 30 nm, a layer comprising titanium nitride TiN of thickness between 1 nm and 30 nm, a third SiNa layer comprising silicon nitride of thickness between 1 nm and 40 nm, a second titanium oxide layer of thickness between 8 nm and 45 nm, said layer being at least partially crystallized in the form of anatase, and the outermost layer of the stack.

[0017] According to preferred modes of the present invention, which may optionally be combined with each other:

[0018] - Said second SiNa layer and third SiNa layer comprising silicon nitride are in contact with said layer comprising titanium nitride TiN. - The thickness of the second titanium oxide layer at least partially crystallized in anatase form is between 8 nm and 35 nm, preferably between 8 nm and 25 nm.

[0019] - The thickness of the layer containing titanium nitride is between 10 nm and 25 nm.

[0020] - The thickness of the first titanium oxide layer is between 15 nm and 35 nm.

[0021] - The thickness of the first layer comprising silicon nitride is between 1 nm and 35 nm.

[0022] - The thickness of the second layer comprising silicon nitride is between 1 nm and 15 nm.

[0023] - The thickness of the third layer comprising silicon nitride is between 1 nm and 35 nm, preferably between 1 nm and 25 nm.

[0024] - The stack comprises at least the following sequence of layers, and preferably consists of the following sequence of layers, starting from the surface of the glass:

[0025] (Glass) / SiNl / TiO / SiN2 / TiN / SiN3 / TiO photocatalytic in which SiN is a layer comprising silicon nitride, TiN is a layer comprising titanium nitride and TiO is a layer comprising titanium oxide.

[0026] - Said stacking of layers does not include layer(s) of silver, gold, platinum or copper.

[0027] The glass article has a light transmission of between 30 and 80%.

[0028] - The glass article has negative a* and b* values ​​in light transmission according to the L,a*, b* colorimetry system.

[0029] Such a glass article can advantageously be used as the front face for the manufacture of multiple glazing, in particular double glazing, exhibiting not only photocatalytic anti-fouling properties but also performing from an energy point of view, i.e. exhibiting good thermal control, while presenting a suitable colorimetry.

[0030] The invention also relates to a multiple glazing system, in particular a double glazing system, comprising at least two substrates (or sheets) of clear glass separated by a gas layer, the substrate described above forming the outward-facing front portion, with the photocatalytic stack being arranged on face 1 of said double glazing. In said multiple glazing system, a thermal control coating comprising at least one layer of silver is disposed on another face of said multiple glazing system, in particular on face 2 or, preferably, on face 3 of the double glazing. Such a configuration makes it possible to fulfill all the objectives mentioned above.

[0031] More specifically the invention also relates to a multiple glazing comprising at least two clear glass substrates separated by a gas layer, incorporating a glass article as described above positioned such that the photocatalytic stack is disposed on the face 1 facing outwards of said multiple glazing, said multiple glazing further comprising a thermal control coating, disposed on another face of said multiple glazing, in particular on face 2 or on face 3 of the multiple glazing, preferably on face 3 of the multiple glazing.

[0032] According to advantageous embodiments of said multiple glazing: said thermal control coating comprises a stack of layers having infrared reflective properties, including at least one silver-based metallic layer, preferably silver. - The stack of layers having infrared reflective properties comprises a succession of layers of dielectric materials placed on either side of said silver-based layer.

[0033] Multiple glazing consists of double glazing, the photocatalytic stack being disposed on face 1 of said double glazing facing outwards, and the thermal control coating preferably comprising at least one layer of silver being disposed on face 2 or face 3 of the double glazing, preferably on face 3.

[0034] The multiple glazing according to the invention has a light transmission in the visible range of between 30 and 60%.

[0035] - The multiple glazing according to the invention has negative a* and b* values ​​in light transmission according to the CIELAB colorimetry system.

[0036] Consequently, such multiple glazings can be configured so that the photocatalytic stack is on face 1, i.e. on the outside of the building, where the titanium oxide layer can fully play its role with regard to dirt and atmospheric pollution.

[0037] This combination of layered stacks therefore makes it possible to offer in the end glass articles and glazing possessing both self-cleaning and anti-fouling properties and thermal control properties and whose colorimetry is that sought.

[0038] Preferably, the glass substrate is a sheet of clear glass. The sheet can be flat or curved and of any size, including those larger than 1 meter. The glass is preferably soda-lime silicate, but other types of glass, such as borosilicate or aluminosilicate, can also be used. The glass can be clear or extra-clear. The thickness of the glass sheet is typically between 0.5 and 19 mm, often between 2 and 12 mm, or even between 4 and 8 mm.

[0039] The photocatalytic stack according to the invention described above preferably does not include layer(s) of silver, gold, platinum or other precious metals or nickel or copper because these layers are either expensive to produce, or may impart poor climatic resistance to the glazing like silver-based layers, which is particularly detrimental when the stack is on face 1 of the glazing.

[0040] The thickness of the titanium nitride layer is adjusted according to the desired light transmission. It varies between 1 and 30 nm, particularly between 10 and 25 nm. The light transmission (in the visible spectrum as defined by standard EN 410:2011) of the glass article according to the invention is preferably between 30 and 80%, particularly between 40 and 70%, and especially between 50% and 65%. Such a value allows for a light transmission of the multiple glazing obtained according to the invention from said glass article greater than or equal to 30%, or even greater than 40%, and potentially up to 60%, or even beyond.

[0041] The silicon nitride layer located beneath the titanium nitride layer is intended to protect the titanium nitride functional layer from diffusion of alkali ions from the substrate and from delamination. The silicon nitride layer deposited above the titanium nitride layer is intended to reduce the intrinsic reflectivity of the metal or nitride layer and to protect the latter from oxidation, corrosion, and mechanical damage (scratches, abrasion, etc.). The material constituting the layer in contact with the TiN functional layer and the material constituting the upper layer in contact with the TiN functional layer is advantageously a silicon nitride, possibly containing aluminum.Such materials are particularly preferred because they provide excellent mechanical and hardening resistance, and can be easily deposited by magnetron sputtering. Each of these layers can be pure or doped. It is thus common to dope silica or silicon nitride layers with an atom such as aluminum, with a Si-to-Al replacement rate of up to 10 or even 15% atomic percentage.

[0042] In the layers according to the invention comprising silicon nitride, said nitride preferably represents at least 50% by weight of said layers, and preferably more than 80% or even more than 90% by weight of said layers. Preferably still, said layers consist essentially of silicon nitride, but may also comprise another metal such as aluminum. Aluminum is used in a well-known manner, in proportions of up to 15% atomic, in silicon targets used for magnetic field-assisted (magnetron-assisted) sputtering deposition of silicon-containing layers, particularly silicon nitride-based layers.

[0043] In the layers according to the invention comprising titanium nitride, the titanium nitride (TiN x) preferably represents at least 50% by weight of said layers, and preferably more than 80% or even more than 90% of said layers. The formulation of the layers, and in particular the value of x, can be obtained conventionally by XPS photoelectron spectrometry, according to techniques well known in the field of materials science. According to a preferred embodiment of the invention, said layers are preferably made essentially of titanium nitride, apart from unavoidable impurities.

[0044] The titanium nitride according to the invention is not necessarily stoichiometric (Ti / N atomic ratio of 1) but can be over- or under-stoichiometric. In an advantageous configuration, the N / Ti ratio is between 1 and 1.2. Also, the titanium nitride according to the invention can comprise a minor amount of oxygen, for example between 1 and 10 mol% oxygen, in particular between 1 and 5 mol% oxygen.

[0045] According to a preferred mode, the titanium nitride layers according to the invention conform to the general formula TiN x O y , in which 1.00 < x < 1.20 and in which 0.01 < y < 0.10.

[0046] In the layers according to the invention comprising titanium oxide, the titanium oxide preferably represents at least 50% by weight of said layers, based on a TiU2 formulation, and preferably more than 80% or even more than 90% of said layers, based on the TiCt formulation. Preferably still, said layers are essentially made up of titanium oxide.

[0047] The titanium oxide in the photocatalytic coating, preferably at least partially in anatase form, can be pure or doped, for example with transition metals (e.g., W, Mo, V, Nb), lanthanide ions, or noble metals (such as platinum, palladium), or even with nitrogen or carbon atoms. These different forms of doping either increase the photocatalytic activity of the material or shift the band gap of the titanium oxide towards wavelengths close to or within the visible spectrum.

[0048] The photocatalytic titanium oxide layer is normally the last layer of the stack deposited on the substrate of the glass article according to the invention; in other words, the layer of the stack furthest from the substrate. It is indeed important that the photocatalytic layer be in contact with the atmosphere and its pollutants. However, it is possible to deposit a very thin layer, generally discontinuous or porous, on top of the photocatalytic layer. This could, for example, be a layer based on noble metals intended to increase the photocatalytic activity of the material. It could also be a thin hydrophilic layer, for example, made of silica, as taught in applications W02005 / 040058 or

[0049] 2007 / 045805.

[0050] The multiple glazing according to the invention preferably has a solar factor (within the meaning of standard NF EN 410:2011) less than or equal to 50%, preferably less than or equal to 40%.

[0051] In the preferred sputtering process according to the invention for deposition, particularly when assisted by a magnetic field (magnetron process), excited species of a plasma dislodge atoms from a target located opposite the substrate to be coated. For the deposition of the titanium oxide layer, the target may, in particular, be metallic titanium or TiO₂. x The plasma must contain oxygen (this is called reactive sputtering). It is also possible to deposit SiaN4-based layers using an aluminum-doped silicon target in a plasma containing argon and nitrogen. The titanium nitride-based functional layer can be deposited using the same techniques with a titanium nitride target or a titanium metallic target, respectively in an inert atmosphere (e.g., argon) or a reactive atmosphere containing nitrogen.

[0052] Alternatively, a chemical vapor deposition (CVD) process can be used to deposit the titanium oxide layer. This process involves the pyrolysis of gaseous precursors that decompose under the influence of substrate heat. Examples of precursors for titanium oxide include titanium tetrachloride, titanium tetraisopropoxide, and titanium tetraorthobutoxide.

[0053] The deposition step is preferably followed by a heat treatment, in particular of the quenching, bending, annealing type, especially when the titanium oxide layer has been deposited by sputtering.

[0054] The invention also relates to a multi-pane glazing unit comprising at least one glass element according to the invention. The glazing unit is preferably double-pane, in the sense that it comprises two substrates or sheets of glass with a gas-filled space between them.

[0055] Such assembled double glazing units (or DGUs for Double Glazing Unit) may, for example, have the configuration: 4-16 (air or argon gas) -4, that is to say, they consist of two 4 mm transparent Planiclear® glass sheets separated by an intermediate gas layer comprising air or a mixture of 90% argon and 10% air by volume, with a thickness of 16 mm, all held together by a frame structure and spacers maintaining a constant distance between the two glass substrates separated by the gas layer.

[0056] Traditionally, the faces of a multi-pane window are numbered from the outside to the inside of the building, with face 1 being the face of the window facing outwards.

[0057] According to one embodiment of the glass article of the invention, the other face of the substrate, besides that coated by the photocatalytic stack, is coated by another stack having thermal control properties, in particular low-emissivity, as described above, and notably comprising at least one silver layer protected by dielectric layers. A multi-pane glazing according to the invention can thus be obtained by incorporating such a glass article into a multi-pane glazing as described above, such that the photocatalytic stack is on face 1 and the thermal control stack is on face 2 of said glazing.

[0058] According to another more preferred embodiment, the other face of the glass article is left bare and multiple glazing, in particular double glazing, is obtained by combining it, according to known techniques, with another glass substrate comprising on one of its faces a stack having thermal control properties of the type described previously, such that the photocatalytic stack is on face 1 and the thermal control stack containing the silver-based layer(s) is on face 3 of said glazing.

[0059] The glazing according to the invention can be advantageously used for buildings, in particular for verandas, facades or roofs and preferably even on any building glazing.

[0060] For other automotive applications, the glazing can also form solar-protective and self-cleaning roofs.

[0061] The invention will be better understood in light of the following non-limiting examples.

[0062] All the examples, comparative or according to the invention, are produced using magnetron sputtering deposition on clear glass substrates marketed under the brand name Planiclear® by the applicant, initially to obtain glass articles with photocatalytic properties, suitable for use in the manufacture of multi-pane glazing. The silicon nitride layers are obtained from a silicon target doped with 8 wt% aluminum, under an atmosphere composed of 45% argon and 55% nitrogen. The titanium nitride layers are obtained from a metallic titanium target, sputtered in an atmosphere composed of 68% argon and 32% nitrogen.It has been verified by XPS (X-rays Photoelectron Spectroscopy) and RBS (Rutherford backscattering spectrometry) that titanium nitride is superstoichiometric under these conditions (x close to 1.1). The titanium oxide layers are obtained from a substoichiometric titanium oxide target under an argon atmosphere containing oxygen with a volume ratio O2 / (Ar+O2) of 6%.

[0063] The samples of the examples according to the invention and comparatives are then subjected to an annealing treatment, at a temperature of 650°C for 10 minutes.

[0064] Table 1 shows the composition and thickness of several examples of glass articles according to the invention (Ex. 1 to Ex. 3) and comparative examples (C1 to C3 according to WO2021 / 123618). The photocatalytic stacking is described in Table 1 below, with the first row corresponding to the layer furthest from the substrate and the last row to the layer in contact with the substrate. As in the rest of the description, the thicknesses are physical thicknesses expressed in nm.

[0065] [Table 1]

[0066] Cl*: example 1 of publication WO2021 / 123618

[0067] C2**: example 2 of publication WO2021 / 123618

[0068] The glass articles thus obtained are then assembled according to the techniques of the art of double glazing with another sheet of glass on one face of which is previously deposited a low-emissivity coating comprising a silver layer and whose composition and layer thicknesses are given below:

[0069] Glass / Si3N4 (8nm) / / ZnO (24nm) / Ag (16nm) / NiCr (0.2nm) / ZnO (20nm) / Si3N4 (17nm) / SnZnOx (9nm)

[0070] More specifically, the double glazing units (or DGU for Double Glazing Unit) assembled according to the examples have the configuration: 4-16 (Ar 90%- Air 10%) -4, that is to say that they consist of two sheets of transparent Planiclear® glass of 4 mm separated by an intermediate gas layer comprising 90% argon and 10% air by volume, with a thickness of 16 mm, all held together by a frame structure and spacers.

[0071] The double glazing is installed so that the photocatalytic layer is located on surface 1 of the double glazing (i.e., the surface facing outwards from the building) and the low-emissivity layer is located on surface 3 of the double glazing (and therefore in the cavity occupied by the gas and protected from the external environment). It should be noted that the numbering is sequential, starting from the outermost glass substrate of the building, when considering the direction of sunlight entering the building; surface 1 therefore corresponds to the glass surface facing outwards from the glazing.

[0072] Table 2 below indicates the optical and energy properties of the double glazing thus obtained: the light transmission (TL) in the visible, in percentages, as defined by standard NF EN 410:2011, the corresponding chromatic values ​​a* and b* in transmission in the international system L*a*b* CIE 1976 (CIELAB), calculated taking into consideration the illuminant D65 and the reference observer CIE-1931.

[0073] [Table 2]

[0074] A comparison of the values ​​obtained shows that the examples according to the invention exhibit optical characteristics after tempering, suitable for use particularly in the building sector:

[0075] - A sufficiently high light transmission to allow proper illumination of the interior of the equipped building.

[0076] - A blue colorimetry in transmission, the coefficients a* and b* being both negative.

[0077] Conversely, double glazing incorporating the glass component according to earlier application WO2021 / 123618 exhibits a positive b* value, which corresponds to a yellow color in the transmission of the glazing. According to a second set of examples, the glass components described in Table 3 below are produced under the same conditions as described above:

[0078] [Table 3]

[0079] Table 4 below shows the optical properties of the glass articles (in single glazing) thus obtained:

[0080] [Table 4] As with the previous examples, the glass components thus obtained are then assembled using the techniques of the art in 4 / 16(Ar) / 4 double glazing (4 cm of glass / 16 cm of argon layer / 4 cm of glass) with another sheet of glass on one face of which the same low-emissivity stack, including a silver layer, as described previously, has been deposited. Table 5 below shows the optical properties of the double glazing thus obtained: [Table 5] It can be seen that the glass article and the glazing according to the invention, unlike the comparative examples, exhibit a sufficiently high light transmission to allow correct illumination of the interior of the equipped building and a blue colorimetry in transmission, the coefficients a* and b* both being negative.

[0081] In addition, their solar factor g allows for good insulation of the building or the passenger compartment equipped with such glazing.

[0082] The stacks according to the invention also exhibit photocatalytic activity and climatic resistances comparable to those described in application WO2021 / 123618.

Claims

DEMANDS 1. Glass article comprising a glass substrate coated on at least one of its faces with a stack of layers comprising, from the surface of said substrate, a first SiNi layer comprising silicon nitride of thickness between 1 nm and 60 nm, a first titanium oxide layer of thickness between 8 nm and 55 nm, a second SiN2 layer comprising silicon nitride of thickness between 1 nm and 30 nm, a layer comprising titanium nitride TiN of thickness between 1 nm and 30 nm, a third SiNa layer comprising silicon nitride of thickness between 1 nm and 40 nm, a second titanium oxide layer of thickness between 8 nm and 45 nm, said layer being at least partially crystallized in anatase form, and the outermost layer of the stack.

2. Glass article according to claim 1, wherein said second SiNa layer and third SiNa layer comprising silicon nitride are in contact with said layer comprising titanium nitride TiN.

3. Glass article according to any one of the preceding claims, wherein the thickness of the second layer of titanium oxide at least partially crystallized in anatase form is between 8 nm and 35 nm, preferably further between 8 nm and 25 nm.

4. Glass article according to any one of the preceding claims, wherein the thickness of the layer comprising titanium nitride is between 10 nm and 25 nm.

5. Glass article according to any one of the preceding claims, wherein the thickness of the first layer of titanium oxide is between 15 nm and 35 nm.

6. Glass article according to any one of the preceding claims, wherein the thickness of the first layer comprising silicon nitride is between 1 nm and 35 nm.

7. Glass article according to any one of the preceding claims, wherein the thickness of the second layer comprising silicon nitride is between 1 nm and 15 nm.

8. Glass article according to any one of the preceding claims, wherein the thickness of the third layer comprising silicon nitride is between 1 nm and 35 nm, preferably between 1 nm and 25 nm.

9. A glass article according to any one of the preceding claims, wherein the stacking comprises at least the following sequence of layers, and preferably consists of the following sequence of layers, starting from the surface of the glass: (Glass) / SiNi / TiO / Si^ / TiN / SiNa / TiO photocatalytic in which SiN is a layer comprising silicon nitride, TiN is a layer comprising titanium nitride and TiO is a layer comprising titanium oxide.

10. Glass article according to any one of the preceding claims, wherein said stacking of layers does not comprise any layer(s) of silver, gold, platinum or copper.

11. Glass article according to any one of the preceding claims, having a light transmission of between 30 and 80%.

12. Glass article according to one of the preceding claims, having negative a* and b* values ​​in light transmission according to the colorimetric system L,a*, b*.

13. Multiple glazing comprising at least two clear glass substrates separated by a gas layer, incorporating a glass article according to one of the preceding claims positioned such that the photocatalytic stack is disposed on the outward-facing face 1 of said multiple glazing, said multiple glazing further comprising a thermal control coating disposed on another face of said multiple glazing, in particular on face 2 or face 3 of the multiple glazing, preferably on face 3 of the multiple glazing.

14. Multiple glazing according to the preceding claim, wherein said thermal control coating comprises a stack of layers having infrared reflective properties, including at least one silver-based metallic layer, preferably silver.

15. Multiple glazing according to claim 13 or 14 in which the stacking of layers with infrared reflecting properties comprises a succession of layers of dielectric materials placed on either side of said silver-based layer.

16. Multiple glazing according to any one of claims 13 to 15, consisting of double glazing, the photocatalytic stack being disposed on the outward-facing face 1 of said double glazing, and the thermal control coating preferably comprising at least one layer of silver being disposed on face 2 or face 3 of the double glazing, preferably on face 3.

17. Multiple glazing according to any one of claims 13 to 16, exhibiting a light transmission in the visible range of between 30 and 60%.

18. Multiple glazing according to any one of claims 13 to 17, having negative a* and b* values ​​in light transmission according to the CIELAB colorimetry system.

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