Photocatalytic cartridge

Abstract

This disclosure relates to a replaceable photocatalytic cartridge for use in a reactor, and a method for producing the replaceable photocatalytic cartridge. The replaceable photocatalytic cartridge being suitable for use within a reactor that photocatalytically splits water, such as a PWS reactor. In one embodiment, the photocatalytic cartridge comprises a container that contains a substrate that is coated with photocatalytic particles, wherein, in use, the photocatalytic cartridge is configured to be removably inserted into a receiving portion of the reactor such that the coated substrate is adapted to participate in a photocatalytic reaction with H2O and solar radiation within the reactor.

Description

PHOTOCATALYTIC CARTRIDGE PRIORITY DOCUMENTS

[0001] The present application claims priority from Australian Provisional Patent Application No. 2024902509 titled “PHOTOCATALYTIC CARTRIDGE” and filed on 12 August 2024, the content of which is hereby incorporated by reference in its entirety. TECHNICAL FIELD

[0002] The present disclosure relates to a photocatalytic cartridge for use in a reactor, and a method for producing the photocatalytic cartridge. In a particular embodiment, the present disclosure relates to a replaceable photocatalytic cartridge for use in a reactor, where the photocatalytic cartridge is removably insertable into a receiving portion of the reactor. In use, the photocatalytic cartridge is exposed to H2O and solar radiation within the reactor, to photocatalytically split the H2O into hydrogen and oxygen. BACKGROUND

[0003] With the ever-increasing demand for energy derived from renewable sources, the focus of many innovators has been to design methods for energy production that is efficient, cost-effective, easy to maintain, and scalable.

[0004] The use of solar energy to split water (H2O) photocatalytically is a promising and simple strategy to produce hydrogen for use as a fuel or feedstock, in a clean and storable manner. In presently available photocatalytic H2O splitting technologies, the hydrogen (H2) and oxygen (O2) evolution reactions take place over a photocatalyst within a reactor, where the produced H2is captured or stored downstream of the reactor. However, existing photocatalysts used within these reactors often suffer from poor physical characteristics and are economically unviable. Some of the poor physical characteristics of existing photocatalysts include being fragile to produce and subsequently install within reactors (thereby reducing their overall lifespan and effectiveness) and being fixtures that form part of the reactor (such that the reactor must be disassembled or replaced in order to replace an inefficient or degraded photocatalyst therein). Economical concerns with existing photocatalysts and reactors include being expensive, difficult to produce, being inefficient at splitting H2O into hydrogen and oxygen due to limitations of the photocatalyst materials, and reactor designs which do not maximise the photocatalyst, H2O, and solar radiation / energy interface.

[0005] Thus, it is against this background and the problems and difficulties associated therewith, that the present invention has been developed, in response to a need to provide a robust method that produces a device comprising a photocatalyst for use in a reactor that photocatalytically splits H2O into hydrogen and oxygen.

[0006] For the purposes of the following description, the referenced “reactor” may be a photocatalytic reactor, a photocatalytic water splitting reactor (i.e. PWS reactor), vessel, or container, that is used for photocatalytically splitting water (hereinafter, interchangeably referred to as “H2O”), that is in either liquid or gaseous form, to produce hydrogen (hereinafter interchangeably referred to as “H2”) and oxygen (hereinafter interchangeably referred to as “O2”) using a radiation source, such as solar radiation. SUMMARY

[0007] Embodiments of the present disclosure relate to a replaceable component for use in a reactor, the component comprising a substrate coated with a photocatalyst, wherein the substrate comprises spheres that are coated with a sol-gel, and subsequently the photocatalyst in a particulate form is adhered onto the surface of the sol-gel coated spheres.

[0008] Embodiments of the present disclosure also relate to a replaceable cartridge for use in a reactor that is for photocatalytically splitting H2O into hydrogen and oxygen. In particular, the replaceable cartridge is a photocatalytic cartridge, that structurally defines a container that is removably inserted into a receiving portion of the reactor. The cartridge also comprising a substrate within the container, wherein the substrate is coated with photocatalytic particles, such that, in use, when the cartridge is within the reactor, the coated substrate is adapted to participate in a photocatalytic reaction with H2O and solar radiation within the reactor, the coated substrate being configured to maximise exposure of the photocatalytic particles to solar radiation, and additionally various features of the cartridge increase the durability of the coated substrate contained therein.

[0009] Embodiments of the present disclosure also relate to a replaceable photocatalytic cartridge for use in a reactor. In particular, the replaceable photocatalytic cartridge comprises a container, and a substrate within the container. The substrate comprising a coating of photocatalytic particles adhered to its surface. Where, in sue, the replaceable cartridge is configured to be removably inserted into a receiving portion of the reactor, and to facilitate exposure of the photocatalytic particles to solar radiation. The contained coated substrate is adapted to participate in a photocatalytic reaction with H2O and solar radiation within the reactor and is configured to detach hydrogen and oxygen bubbles generated from H2O during the photocatalytic reaction from the coated substrate.

[0010] Embodiments of the present disclosure also relate to a method for producing a replaceable cartridge for use in a reactor. In particular, the cartridge is a photocatalytic cartridge, and the method comprises steps that relate to adhering photocatalytic particles to a substrate such that the photocatalytic particles form a coating on the substrate that is deposited within a container to form the replaceable photocatalytic cartridge, wherein the contained coated substrate is adapted to participate in a photocatalytic reaction with H2O and solar radiation within the reactor, the coated substrate being configured to maximise exposure of the photocatalytic particles to solar radiation, and additionally various features of the cartridge increase the durability of the coated substrate contained therein.

[0011] Further embodiments of the present disclosure relate to a method for coating a substrate with photocatalytic particles, wherein the resultant coated substrate that is subsequently contained within a frame or container of a replaceable cartridge that is removably insertable for use within a reactor for the purpose of photocatalytically splitting H2O into hydrogen and oxygen.

[0012] According to a first aspect, there is provided a replaceable photocatalytic cartridge for use in a reactor, the cartridge comprising: a container; a substrate within the container, wherein the substrate comprises a coating of photocatalytic particles adhered to its surface; wherein, in use, the replaceable photocatalytic cartridge is configured to be removably inserted into a receiving portion of the reactor such that: the coated substrate is adapted to participate in a photocatalytic reaction with H2O and solar radiation within the reactor; and wherein in combination the replaceable photocatalytic cartridge and the coated substrate are configured to facilitate exposure of the photocatalytic particles to solar radiation and detachment of hydrogen and oxygen bubbles generated from H2O during the photocatalytic reaction from the coated substrate.

[0013] In one embodiment, the substrate comprises any one of a plurality of spheres, a plate, a sheet, a slide, a film, a particulate material, a material with a mesh structure, or a sol-gel product, wherein any one or more of these comprise the coating of photocatalytic particles adhered thereto.

[0014] In one embodiment, the photocatalytic particles are physically adhered to the substrate. In this embodiment, the photocatalytic particles may be adhered to the substrate via van der Waals forces.

[0015] In one embodiment, the photocatalytic particles are chemically adhered to the substrate. In this embodiment, the photocatalytic particles may be adhered to the substrate via hydrogen bonding or a chemical linker.

[0016] In one embodiment, the substrate comprises the plurality of spheres, wherein each sphere is coated with the photocatalytic particles to increase the surface area of the photocatalytic particles which are adhered to the coated substrate.

[0017] In one embodiment, the plurality of spheres coated with the photocatalytic particles maximise photocatalytically active sites on the coated substrate exposed to solar radiation.

[0018] In one embodiment, the plurality of spheres are polymeric spheres and a surface of the polymeric spheres is heated prior to adhering the photocatalytic particles to a surface of the polymeric spheres.

[0019] In one embodiment, the plurality of spheres coated with the photocatalytic particles are fluid or mobile within the container, and in use, fluidity or mobility of the coated spheres is configured to facilitate exposure of the photocatalytic particles to solar radiation and detachment of hydrogen and oxygen bubbles generated from H2O during the photocatalytic reaction from the coated spheres.

[0020] In one embodiment, the plurality of spheres coated with the photocatalytic particles are fluid within the container due to a flow of gases and / or liquids within the reactor that flows between and / or through the coated spheres.

[0021] In one embodiment, the plurality of spheres coated with the photocatalytic particles are spaced to form a fixed porous structure within the container that enables gases and liquids within the reactor to flow therebetween.

[0022] In one embodiment, the spheres are coated with a sol-gel.

[0023] In one embodiment, the sol-gel increases durability of the spheres and aids in the adhesion of the photocatalytic particles.

[0024] In one embodiment, the spheres are a polymeric material, a glass material, or a sol-gel material.

[0025] In one embodiment, the spheres are sized between 0.015mm to 20mm. In an alternative embodiment, the spheres are sized larger than 1 micron.

[0026] In one embodiment, the spheres are hollow spheres.

[0027] In one embodiment, where the substrate comprises a material with a mesh structure, the mesh structure may be one of a wire mesh or a fibre mesh. In another embodiment, where the substrate comprises a material with a mesh structure, the mesh structure may be quartz fibres.

[0028] In one embodiment, the container comprises a porous portion, wherein, in use, the porous portion permits the flow of gas and liquid therethrough to the coated substrate.

[0029] In one embodiment, the body comprises a frame and a cover that cooperate to define the container, wherein the cover is a fritted glass.

[0030] In one embodiment, installing the cover onto the frame secures the polymeric spheres as a fixed structure within the container configured to maximise exposure of photocatalytic particles to solar radiation.

[0031] In one embodiment, the substrate comprises a sol-gel product and the photocatalytic particles are embedded within the sol-gel product and / or adhered on a surface of the sol-gel product. In this embodiment, the photocatalytic particle embedded sol-gel product are loosely bound, or clustered together, within the container.

[0032] In one embodiment, the container further comprises a suspension of photocatalytic particles within the container.

[0033] In one embodiment, the substrate is adapted to participate in the photocatalytic reaction with H2O within the reactor and solar radiation that is incident to the reactor.

[0034] According to another aspect, there is provided a method of producing a replaceable photocatalytic cartridge for use in a reactor, the method comprising: providing at least one substrate; heating the substrate to an adhering temperature, the adhering temperature between a softening temperature and a melting temperature of the substrate; contacting the heated substrate to photocatalytic particles to adhere the photocatalytic particles to the substrate; allowing the photocatalytic particles to bind onto the substrate and form a coating on the substrate; depositing the coated substrate into a container defined by a body to form the replaceable photocatalytic cartridge, wherein the contained coated substrate is adapted to participate in a photocatalytic reaction with H2O and solar radiation within the reactor that maximises exposure of the photocatalytic particles to solar radiation; and inserting the replaceable photocatalytic cartridge into a receiving portion of the reactor.

[0035] In one embodiment, the at least one substrate comprises any one of a plurality of spheres, a plate, a sheet, a slide, a film, a particulate material, a material with a mesh structure, or a sol-gel product, wherein the plurality of spheres, the plate, the sheet, the slide, the film, or the material with a mesh structure is a polymeric or glass material.

[0036] In one embodiment, the substrate is coated with a sol-gel using a process that includes: preparing a sol comprising a solvent, and one or more precursor compounds; applying the sol to the substrate; allowing the sol to undergo gelation and form a gel coating on the substrate; and curing the gel to form a solidified coating adhered to the substrate.

[0037] In one embodiment, the sol-gel coated substrate is maintained at an appropriate temperature and humidity, and the sol-gel coated substrate contacts the photocatalytic particles to cure the photocatalytic particles to the sol-gel coated substrate and form the coated substrate deposited at step (c).

[0038] In one embodiment, the sol-gel coating aids in the adhesion of the photocatalytic particles to the substrate and increases the durability of the substrate.

[0039] In one embodiment, the substrate comprises the plurality of spheres, wherein each sphere is coated with photocatalytic particles to increase the surface area of the photocatalytic particles which are adhered to the coated substrate and maximise photocatalytically active sites on the coated substrate exposed to solar radiation.

[0040] In one embodiment, the plurality of spheres coated with the photocatalytic particles are fluid or mobile within the container, and in use, fluidity or mobility of the coated spheres maximise exposure of the photocatalytic particles to solar radiation and aids in hydrogen and oxygen bubble detachment from the surface of the spheres.

[0041] In one embodiment, the plurality of spheres coated with the photocatalytic particles are spaced to form a fixed porous structure within the container that enables gases and liquids within the reactor to flow therebetween.

[0042] According to another aspect, there is provided a method of forming a replaceable photocatalytic cartridge for use in a reactor, the method comprising: preparing at least one substrate; applying photocatalytic particles to the substrate with a binder to adhere the photocatalytic particles to the substrate; allowing the photocatalytic particles to bind onto the substrate and form a coating on the substrate; depositing the coated substrate into a container to form the replaceable photocatalytic cartridge, wherein the contained coated substrate is adapted to participate in a photocatalytic reaction with H2O and solar radiation within the reactor, and in combination the replaceable photocatalytic cartridge and the coated substrate are configured to facilitate exposure of the photocatalytic particles to solar radiation; and inserting the replaceable photocatalytic cartridge into a receiving portion of the reactor.

[0043] According to a further aspect, there is provided a composition comprising: photocatalytic particles activated by light, the photocatalytic particles being capable of photocatalytically splitting H2O into hydrogen and oxygen; a substrate comprising a plurality of spheres sized between 0.015mm to 20mm; wherein the photocatalytic particles are adhered to a surface of the substrate by heating the substrate to an adhering temperature and contacting the photocatalytic particles, and agitating the substrate comprising the photocatalytic particles adhered thereto to create the composition; and wherein, in use, the composition, when applied to a surface optimises exposure of the photocatalytic particles to solar radiation incident to the surface.

[0044] According to yet a further aspect, there is provided a replaceable photocatalytic cartridge for use in a reactor. The cartridge comprising: a container; a substrate within the container, wherein the substrate comprises a coating of photocatalytic particles adhered to its surface; wherein, in use, the replaceable photocatalytic cartridge is configured to be removably inserted into a receiving portion of the reactor such that: the coated substrate is adapted to participate in a photocatalytic reaction with H2O and solar radiation within the reactor; and wherein in combination the replaceable photocatalytic cartridge and the coated substrate are configured to facilitate exposure of the photocatalytic particles to solar radiation. BRIEF DESCRIPTION OF DRAWINGS

[0045] Embodiments of the present disclosure will be discussed with reference to the accompanying drawings wherein:

[0046] Figure 1 is a perspective view of an embodiment of a photocatalytic cartridge and a reactor, illustrating the cartridge prior to insertion into a receiving portion of the reactor and where the reactor is receiving radiation from a radiation source such as solar radiation;

[0047] Figure 2 is a perspective view of the photocatalytic cartridge and reactor of Figure 1, where the photocatalytic cartridge is inserted into the receiving portion of the reactor and is located within a reactive environment within the reactor;

[0048] Figure 3 is a schematic view along A-A of the photocatalytic cartridge and reactor of Figure 2;

[0049] Figure 4 is an exploded view of the photocatalytic cartridge of Figures 1 to 3;

[0050] Figure 5 is a schematic side view of the photocatalytic cartridge of Figures 1 to 4;

[0051] Figure 6 is a process view of an embodiment of a substrate comprising spheres utilised within the photocatalytic cartridge of Figures 1 to 5, illustrating a process of combining the substrate 20 with photocatalytic particles 30 to form a coated substrate 20a;

[0052] Figure 7 is an exploded view of an alternative embodiment of a photocatalytic cartridge for use in a reactor, where the illustrated photocatalytic cartridge comprises a substrate 20 comprising a polymer / polymeric layer;

[0053] Figure 8 is a schematic side view of the photocatalytic cartridge of Figure 7;

[0054] Figure 9 is a process view of the substrate 20 within the photocatalytic cartridge of Figures 7 and 8, illustrating a process of combining the substrate 20 with photocatalytic particles 30 to form the coated substrate 20a;

[0055] Figure 10 is an exploded view of a further alternative embodiment of a photocatalytic cartridge for use within a reactor, where the illustrated photocatalytic cartridge comprises a substrate comprising a meshed structure;

[0056] Figure 11 is a schematic side view of the photocatalytic cartridge of Figure 10;

[0057] Figure 12 is a perspective view of an alternative embodiment of a photocatalytic cartridge for use within a tubular (or cylindrical) reactor, illustrating the cartridge prior to insertion into a receiving portion of the reactor and where the reactor is receiving radiation from a radiation source such as solar radiation;

[0058] Figure 13 is a process flow diagram illustrating, in one embodiment, preparation of a substrate, which may be a polymeric sphere, to comprise photocatalytic particles coated thereon;

[0059] Figure 14 is a process flow diagram illustrating, in one embodiment, preparation of a substrate, which may be a glass sphere or a glass bead, that is coated with a sol-gel and subsequently coated with photocatalytic particles thereon;

[0060] Figure 15 is a process flow diagram illustrating, in one embodiment, preparation of a substrate, which may be a glass sphere or a glass bead, where the surface of the sphere / bead is etched and subsequently coated with a mixture comprising both photocatalytic particles and a sol-gel;

[0061] Figure 16 is a process flow diagram illustrating, in one embodiment, preparation of a substrate, which may be a polymer / polymeric layer, to comprise photocatalytic particles coated thereon;

[0062] Figure 17 is a process flow diagram illustrating, in one embodiment, preparation of a substrate, which may be a polymer / polymeric layer, that is first sandblasted, or softened with a solvent, prior to being coated with photocatalytic particles. The inventors note that by first sandblasting, or softening, the polymer / polymeric layer prior to coating, the adhesion of the photocatalytic particles is improved;

[0063] Figure 18 is a process flow diagram illustrating, in one embodiment, preparation of a substrate, which may be a glass sheet or a glass slide, where the surface of the sheet / slide is etched or sandblasted, and subsequently is coated with photocatalytic particles. The inventors note that by etching, or sandblasting, the glass sheet, or glass slide, prior to coating, the adhesion of the photocatalytic particles is improved;

[0064] Figure 19 is a process flow diagram illustrating, in one embodiment, preparation of a substrate, which may be a glass sheet or a glass slide, where the surface of the sheet / slide is etched or sandblasted, then coated with a sol-gel, and subsequently coated with photocatalytic particles. The inventors note that by the additional step of including the sol-gel coating, the durability of the substrate coated with photocatalytic particles is increased, and this also improves the adhesion of the photocatalytic particles;

[0065] Figure 20 is a process flow diagram illustrating, in one embodiment, preparation of a substrate, which may be a glass sheet or a glass slide, where the surface of the sheet / slide is etched or sandblasted, and subsequently is coated with a mixture comprising both photocatalytic particles and a sol-gel. The inventors note that the etched, or sandblasted, surface of the glass sheet / slide improves the adhesion of the photocatalytic particle and sol-gel mixture that is subsequently coated thereon; and

[0066] Figure 21 is a photograph, illustrating a coated substrate, which in this instance is a sphere coated with photocatalytic particles.

[0067] In the following description, like reference characters designate like or corresponding parts throughout the figures.DESCRIPTION OF EMBODIMENTS

[0068] Referring to any one of the Figures, there is disclosed a replaceable photocatalytic cartridge 10, where the cartridge 10 is for use within a reactor 100, such that the purpose of the cartridge 10 is to be a replaceable element, or component, of the reactor 100 that serves the purpose of photocatalytically splitting H2O within the reactor, into hydrogen and oxygen. There is also disclosed a method of producing the replaceable photocatalytic cartridge 10 for use in the reactor 100.

[0069] The replaceable photocatalytic cartridge 10 comprises a body 11 shaped to define a container 12. A substrate 20 within the container 12, wherein the substrate 20 comprises a coating of photocatalytic particles 30 adhered to a surface thereof to form a coated substrate 20a. Wherein, in use, the replaceable photocatalytic cartridge 10 is configured to be removably inserted into a receiving portion 110 of a reactor 100 such that: the coated substrate 20a is adapted to participate in a photocatalytic reaction with H2O and solar radiation 200 within the reactor 100, and, in combination, the replaceable photocatalytic cartridge 10 and the coated substrate 20a are configured to facilitate exposure of the photocatalytic particles 30 to solar radiation 200 and detachment of hydrogen and oxygen bubbles, that are generated from H2O during the photocatalytic reaction, from the surface of the coated substrate 20a.

[0070] It will be appreciated that in any one of the embodiments that follow, the disclosed substrate 20 is referred to when it is prior to it being coated with photocatalytic particles 30, and the disclosed coated substrate 20a is referred to when it has been coated with photocatalytic particles 30. Accordingly, it will be understood that, in use, the replaceable photocatalytic cartridge 10, when removably inserted into the receiving portion 110 of the reactor 100, will comprise and contain the coated substrate 20a.

[0071] It will be appreciated that the container 12 is any structure that forms a space, that is capable of enclosing, containing, or holding a coated substrate 20a therein. The body 11 may comprise a frame 13 and a cover 14 that cooperate to define the container 12.

[0072] In one embodiment, the cover 14 is fritted glass. In another embodiment, the cover 14 is a porous film or other porous material. In the embodiment that the cover 14 is a fritted glass, in use when the replaceable photocatalytic cartridge 10 is within the receiving portion 110 of the reactor 10, the fritted glass cover 14 allows the flow of hydrogen, oxygen, and H2O therethrough.

[0073] In one embodiment, the container 12 comprises a porous portion, which may be the cover 14, or a portion of the frame 13, wherein, in use, the porous portion of the container 12 permits the flow of gas and liquid there through to the coated substrate 20a.

[0074] For the purposes of the following description, the substrate 20 will be understood to be a base material on which subsequent processing, such as method steps, is conducted. For example, the substrate 20 may be one or more of a plurality of spheres, a plate (e.g. a glass plate), a slide (e.g. a glass slide), a polymeric layer, polymeric spheres, glass spheres, hollow spheres, beads, a film, a particulate material, a material with a mesh structure, or another solid material, such as one formed by a sol-gel process (sol-gel material, or sol-gel product), for the purposes of being a base material to which the photocatalytic particles 30 are coated thereon, and used within the disclosed replaceable photocatalytic cartridge 10 and method described herein.

[0075] For illustrative purposes, Figures 4 to 11 show embodiments of the photocatalytic cartridge 100 comprising various examples of coated substrate 20a. Figures 4 to 6 illustrate the photocatalytic cartridge 100 comprising a substrate which may be a plurality of spheres 20 that are coated with photocatalytic particles 30 to create a coated substrate 20a. Figures 7 to 9 illustrate the photocatalytic cartridge 100 comprising a substrate which may be a polymer / polymeric layer 20 that is coated with photocatalytic particles 30 to create a coated substrate 20a. Figures 10 and 11 illustrate the photocatalytic cartridge 100 comprising a substrate which may be a material with a mesh structure 20 that is coated with photocatalytic particles 30 to create a coated substrate 20a.

[0076] It will be appreciated that the reactor 100 discussed herein itself is not claimed by the present disclosure, however, with reference to either one of Figures 1 to 3 or 12, the reactor 100 may comprise a receiving portion 110, or a receptacle, that is sized and shaped to receive and contain the replaceable photocatalytic cartridge 10 therein. This receiving portion 110, or receptacle, of the reactor 100 may position the replaceable photocatalytic cartridge 10 therein such that, in use, the cartridge 10 is accessible and replaceable from this position. It will be apparent from the present disclosure, that the replaceable photocatalytic cartridge 10, of any one of the embodiments below, used within a reactor 100 is particularly advantageous in an operation where the reactor 100 is continuously photocatalytically splitting H2O, such that the cartridge 10 may be replaced, or removably inserted, from the reactor 100, when a previous cartridge 10 has been depleted or is no longer efficient in splitting H2O, with minimal disruption to the continuous operation of the reactor 100. Preferably, the replacement of the depleted replaceable photocatalytic cartridge 10 with the new cartridge 10 would occur at a time when it is not possible for the photocatalyst to split H2O, such as at night. Accordingly, an advantage of the disclosed replaceable photocatalytic cartridge 10 is that it easily replaced from within a receiving portion 110 of the reactor 100, convenient to use, and distinct from the reactor 100. It will also become apparent, from the description that follows, the structure of the replaceable photocatalytic cartridge 10 is robust and facilitates efficient water splitting, particularly when compared to existing photocatalyst sheets that are typically used within reactors.

[0077] The reactor 100, as illustrated in any one of Figures 1 to 3, may comprise a window 130 that permits the solar radiation 200 to pass there through to the receiving portion 110, and / or reactive environment 130, therein. Additionally, the reactor 100 may comprise one or more blind holes that are configured to be in alignment with corresponding blind holes on the replaceable photocatalytic cartridge 10, such that one or more bolts may be driven through the corresponding blind holes on the cartridge 10 and reactor 100 to secure the cartridge 10 to the reactor 100. Further, the replaceable photocatalytic cartridge 10 may comprise a seal 15 that enables the cartridge 10 to form a seal against the reactor 100 when it is within the receiving portion 110.

[0078] It will further be appreciated that the photocatalytic cartridge, according to any one of the disclosed embodiments, is not limited to use within a particular type or shape of reactor 100, that is, the reactor 100 may be rectangular shaped such as that illustrated in Figures 1 to 3, or it may be a tubular, or cylindrical, shaped reactor such as that illustrated in Figure 12.

[0079] The receiving portion 110 of the reactor 100 comprises a reactive environment 120. This reactive environment 120 facilitates the photocatalytic reaction with H2O and solar radiation 200 occurring within the reactor 100, and accordingly, the replaceable photocatalytic cartridge 10 in use, is inserted, or received, into the receiving portion 110 locating the substrate 20 coated with photocatalytic particles 30 within the reactive environment 120 such that the coated substrate 20a is adapted to participate in the photocatalytic reaction to split H2O into hydrogen and oxygen.

[0080] It will be appreciated that the substrate 20 coated with photocatalytic particles 30 being adapted to participate may be considered that the coated substrate 20a is “suitable” or “intended” for performing the task by “taking part in” or “contributing to” the broader process of producing H2and O2from H2O within the reactive environment 120 of the reactor 100.

[0081] The receiving portion 110 of the reactor 100 may position the replaceable photocatalytic cartridge 10 within the reactive environment 120 therein such that, one or more surfaces, or sides, or features, such as the coated substrate 20a of the cartridge 10 is exposed to solar radiation 200 received by the reactor 100, from a radiation source, enabling the coated substrate 20a to participate in photocatalytically splitting H2O within the reactor 100 into H2and O2. Further, the reactor 100 referenced herein, may interchangeably be considered a ‘reactor cell’ that is part of a system comprising several reactors 100 for the purposes of photocatalytically splitting H2O to produce H2 and O2that may be utilised as chemical fuels or feedstocks.

[0082] In one embodiment, broadly illustrated within Figures 10 and 11, the inventors envisage an example where the substrate 20 comprises a material with a mesh structure, the mesh structure may beone of a wire mesh, a fibre mesh, a polymer mesh that is transparent / translucent, or a mesh structure such as quartz fibres.

[0083] In one embodiment, where the substrate 20 comprises the plurality of spheres, each sphere is coated with the photocatalytic particles 30 to increase the surface area of the photocatalytic particles 30 which are adhered to the coated substrate 20a. In this way, it will be understood that an advantage, and aim, of the present disclosure is to maximise photocatalytically active sites on the coated substrate 20a, by increasing the surface area of the photocatalytic particles 30. In this embodiment, the plurality of spheres coated with the photocatalytic particles 30 maximise photocatalytically active sites on the coated substrate 20a exposed to solar radiation 200. Advantageously, this improves solar radiation absorption and facilitates increased reaction efficiency (higher photocatalytic efficiency). In essence, in this embodiment where the substrate 20 comprises the plurality of spheres that are within the container 12 of the replaceable photocatalytic cartridge 10, there is an increased surface area of photocatalytic particles 30 resulting in: 1. Maximised / increased / greater active site availability (more photocatalytic sites) where solar radiation induced reactions can occur; 2. Improved solar radiation absorption, as more active sites can ‘trap more solar radiation’ as it forms a ‘porous structure’; 3. Improved diffusion / interaction between photocatalytic particles and H2O; 4. Improved hydrogen and oxygen flow off and around the spheres to facilitate bubble detachment from the surface of the photocatalyst; and 5. Improved reaction efficiency.

[0084] In one embodiment, initially, the substrate 20 comprises a sol-gel product, and subsequently, the photocatalytic particles 30 are embedded within the substrate 20 comprising the sol-gel product, and / or adhered on a surface of the sol-gel product. In this way, the coated substrate 20a comprises the substrate 20 with the sol-gel product into which the photocatalytic particles 30 are embedded. The photocatalytic particles 30 embedded within the sol-gel product, that is the coated substrate 20a in this embodiment, may form an agglomerate within the container 12. Accordingly, in this embodiment, the coated substrate 20a comprising the photocatalytic particle 30 embedded sol-gel product may be loosely bound, or clustered together, within the container 12, with physical forces such as van der Waals forces, electrostatic forces, or other chemical bonds, to sit within the replaceable photocatalytic cartridge 10.

[0085] In another embodiment, the container 12 may further comprise a suspension comprising photocatalytic particles 30. In this embodiment, the suspension comprising photocatalytic particles 30further maximise photocatalytically active sites within the container, inclusive of the coated substrate 20a, that are exposed to solar radiation 200.

[0086] The method of the present disclosure includes steps that comprises the use of a substrate 20, and coating the substrate 20 with photocatalytic particles 30, where the resultant coated substrate 20a is a component of the replaceable photocatalytic cartridge 10 for use in a reactor 100.

[0087] The present disclosure broadly relates to a method of producing a replaceable photocatalytic cartridge 10 for use in the reactor 100. The method comprises several steps, initially the method involves providing at least one substrate 20. Subsequently, in the instance that the substrate 20 is of a polymeric material, the substrate 20 is heated to an adhering temperature, where the adhering temperature is between a softening temperature and a melting temperature of the substrate 20. Next, contacting the heated substrate 20 to photocatalytic particles 30 to adhere the photocatalytic particles 30 to the substrate 20. Then, allowing the photocatalytic particles 30 to bind onto substrate 20 and form a coating on substrate 20. Next, depositing the coated substrate 20a into a container 12 defined by a body 11 to form the replaceable photocatalytic cartridge 10, wherein the contained coated substrate 20a is adapted to participate in a photocatalytic reaction with H2O and solar radiation 200 within the reactor 100 that maximises exposure of the photocatalytic particles 30 to solar radiation 200, and finally, inserting the replaceable photocatalytic cartridge 10 into a receiving portion 110 of the reactor 100.

[0088] At the step of allowing the photocatalytic particles 30 to “bind” onto the substrate 20, it will be understood that the term “bind” may encompass various methods of adhesion, including both chemical adhesion and physical adhesion. Examples of binding the photocatalytic particles 30 onto the substrate 20 may include any one, or more of, chemical reactions such as covalent, ionic, or hydrogen bonds, or physical adhesion such as van der Waals forces, electrostatic forces, or another mechanical binding / interlocking means. It will be appreciated that other examples of “binding” are envisaged, beyond those disclosed.

[0089] Within the above method, the substrate 20 may also be coated with a sol-gel made using a sol- gel process. An example of this process may be: i. preparing a sol comprising a solvent, and one or more precursor compounds; ii. applying the sol to the substrate; iii. allowing the sol to undergo gelation and form a gel coating on the substrate; and iv. curing the gel to form a solidified coating adhered to the substrate.

[0090] Within the above sol-gel process, at step i., the solvents may include any one or more of methanol, ethanol, acetonitrile, and others. Additionally, the one or more precursor compounds mayinclude tetraethyl orthosilicate, tetramethyl orthosilicate, triethoxy(octyl)silane, triethoxymethylsilane, (3-aminopropyl) triethoxysilane, and others. The inventors note that water and an acid or a base catalyst may also be used, and in addition to the steps, there may be a drying control agent utilised such as formamide.

[0091] Advantageously, the sol-gel process that coats the substrate 20 with a sol-gel, and aids in the adhesion of the photocatalytic particles 30 to the substrate 20 and increases the durability of the resultant coated substrate 20a.

[0092] It will be appreciated that within the step of adhering the photocatalytic particles 30 to the substrate 20, it may be considered that the photocatalytic particles 30 is ‘coating’ the substrate 20 to form the coated substrate 20a. It will be appreciated that when the coated substrate 20a is contained within the container 12 of the replaceable photocatalytic cartridge 10, the contained coated substrate 20a results in a structure 70, where that structure 70 optimises exposure of the photocatalytic particles 30 to solar radiation that is incident to the cartridge 10.

[0093] For the purposes of this description, references to solar radiation 200 may be interchangeably used with simply ‘radiation’, where this radiation comprises components (UV, IR, high energy, low energy, etc.) that are utilised by the photocatalyst particles 30 within the replaceable photocatalytic cartridge 10 to photocatalytically split H2O. It will be appreciated that this utilised ‘radiation’ may be concentrated, or reflected, from a source, to subsequently be utilised by the photocatalyst particles 30 within the replaceable photocatalytic cartridge 10. It will further be appreciated that references to solar radiation 200 within the disclosed replaceable photocatalytic cartridge 10, and methods of producing the same, may be solar radiation 200 that is incident to the reactor 100 such that it participates within the reactive environment 120 to facilitate the photocatalytic reaction with H2O occurring within the reactor 100, and accordingly, the photocatalytic particles 30 coated on the substrate 20 of the replaceable photocatalytic cartridge 10.

[0094] In one embodiment, where the substrate 20 comprises a plurality of spheres, the spheres may be sized between 0.015mm (i.e.15 micron) to 20mm. The inventors note that this sizing of the spheres may be selected due to the ease of manufacture and ease of containment within the container 12 of the photocatalytic cartridge 10. The inventors also envisage that it is possible to utilise spheres, such as silica spheres, that are sized 0.0001mm (i.e.1 micron).

[0095] In one embodiment, at the method step of contacting the heated substrate 20 to the photocatalytic particles 30, a surface of the heated substrate 20 contacts the photocatalytic particles 30, and the photocatalytic particles 30 are adhered to the surface of the substrate 20. In this embodiment, the photocatalytic particles 30 is physically adhered to the substrate 20. In one example, thephotocatalytic particles 30 may be “dusted” onto the substrate 20 to contact and adhere thereto. In another example, the substrate 20 and the photocatalytic particles 30 are placed into a bath, where the substrate 20 is between a softening temperature and a melting temperature, and subsequently the photocatalytic particles 30 is adhered onto the substrate 20 once they make contact. In yet another example, as an alternative to heating the substrate 20 to be between a softening temperature and a melting temperature, the substrate 20 may be softened with the use of a solvent, such that once the substrate 20 is softened, the photocatalytic particles 30 is adhered onto the substrate 20 once they make contact. It will be appreciated that these are only some examples of how the photocatalytic particles 30 may be adhered to the substrate 20, and other examples beyond those discussed herein are anticipated, with the purpose of this step in the method being that once the substrate 20 is in a condition for contacting and adhering thereto (such as the substrate 20 being between a softening temperature and a melting temperature), the photocatalytic particles 30 contact the substrate 20 to result in physical adhesion.

[0096] In one embodiment, best illustrated by Figure 13, an example is provided illustrating the substrate 20 as a single polymeric sphere 20. The sphere 20 in this example may undergo several steps, which may include; i. Heating the substrate / sphere 20 to above Tg (e.g. Tg of styrene) to soften, or alternatively, softening the substrate / sphere 20 with a solvent; ii. Coating the substrate / sphere 20 with photocatalyst (i.e. photocatalytic particles 30); iii. Heat that sample to ensure that the photocatalyst (i.e. photocatalytic particles 30) have adhered

[0097] In this above embodiment, the photocatalytic particles 30 are physically adhered to the substrate / spheres 20. Figure 16 illustrates an example of the above embodiment where the substrate 20 is shown as a polymer / polymeric layer, or a slide, that may undergo the same steps above.

[0098] In an alternative embodiment, best illustrated by Figure 14, where the substrate 20 is a material, such as glass or glass beads / spheres, this material 20 may have its surface coated with a sol- gel material that is aged to form a sol-gel coated substrate 23. Subsequently, the surface of the sol-gel coated substrate 23 contacts the photocatalytic particles 30, and the photocatalytic particles 30 are adhered to the surface of the sol-gel coated substrate 23. The sol-gel coating may be formed from smaller molecules by conversion of precursors in solution into a colloidal solution that acts as an integrated network (gel). During experimentation, the inventors note that the reaction, to create the sol-gel coating, may require a controlled hydrolysis of a metal alkoxide precursor, typically silicon- based, to produce a porous metal hydroxide gel. The extent of this reaction and porosity may depend on the metal hydroxide gel formed and the temperature that it is heated to. The porosity may also bedetermined by the precursor:water ratio, pH, cosolvent, and whether a mixture of metal alkoxide precursors is used. Note that beads are typically formed above a certain pH and films are formed below a certain pH.

[0099] In the above embodiment, where the photocatalytic particles 30 is physically and / or chemically adhered to the surface of the sol-gel coated substrate 23, the photocatalytic particles 30 (or photocatalyst powder) is dusted onto the sol-gel coated substrate 23.

[0100] In an alternative to the above embodiment, best illustrated by Figure 15, before the substrate 20 has its surface coated with the sol-gel material, the photocatalytic particles 30 may be mixed into a sol-gel mixture 24, during the forming of the sol-gel coating for the substrate 20. Once mixed into the sol-gel mixture 24, the mixture may then be applied to the substrate 20 (which may be one or more of a plurality of spheres, a plate, a slide, a polymeric layer, polymeric spheres, glass spheres, hollow spheres, beads, a film, a particulate material, a material with a mesh structure, or another solid materials) using a paint brush (or another alternative applicator). In an alternative to the paint brush application, once mixed into the sol-gel mixture 24, the mixture may then be applied to the substrate 20 by spray coating using either an airless or air sprayer comprising the photocatalytic particles 30. Alternative application techniques beyond those discussed herein are envisaged.

[0101] In the above embodiment, where the substrate 20 may be a glass bead, or a glass slide, or the like, a surface of the glass may be etched prior to coating the substrate 20 with the sol-gel material. The inventors note that by etching the surface of the glass prior to coating with the sol-gel material, or the photocatalytic particles 30, the physical adhesion between the photocatalytic particles 30 and the glass substrate 20 was improved.

[0102] In the above embodiments, where item 20a comprises the sol-gel coating 23, the temperature of the substrate 20 to allow it to physically adhere to the photocatalytic particles 30 may be approximately 70 °C.

[0103] The inventors have performed various tests of polymers, that may be used within the disclosed methods as the substrate 20, to determine temperature ranges for heating the substrate 20. At a high level, the inventors note that a Tg range of 70 °C to 200 °C may be applied to most example polymers disclosed herein, to be used by the disclosed method, as the softening temperature to melting temperature range thereof.

[0104] Within the method step of heating the substrate 20 to the adhering temperature, this heat may be applied to the substrate 20 by heat sources such as an oil bath or a hotplate. Otherlaboratory, and non-laboratory heat sources are envisaged for heating the substrate 20 to the adhering temperature not described herein.

[0105] In one embodiment, the photocatalytic particles 30 may be physically adhered to the substrate 20 by heating the substrate 20 and contacting the photocatalytic particles 30, wherein the photocatalytic particles 30 are adhered to the substrate 20 via van der Waals forces. In an alternative to this embodiment, the photocatalytic particles 30 may be chemically adhered to the substrate 20 via hydrogen bonding or a chemical linker. It will be appreciated that other potential adhesion mechanisms are envisaged, such as other chemical bonds beyond those disclosed.

[0106] General equations that relate to embodiments of the present disclosure and discussed herein are documented below, being chemical reactions occurring within method steps, to provide a substrate 20 that is coated with photocatalytic particles 30, or to provide a substrate 20 with a sol-gel thereon that is subsequently coated with photocatalytic particles 30, to resultantly produce a coated substrate 20a for use within any one of the embodiments of the photocatalytic cartridge 10. (^^^^^)௫ − ^^ − ^^^^ + ^^^^ − ^^ℎ^^^^^^^^^^^^^^^^^^^^^^ → (^^^^^)௫ − ^^ − ^^ − ^^ℎ^^^^^^^^^^^^^^^^^^^^^^ + ^^ଶ^^Equation 1(^^^^^)௫ − ^^(^^ଶ) − ^^^^ + ^^^^ − ^^ℎ^^^^^^^^^^^^^^^^^^^^^^ → (^^^^^)௫ − ^^(^^ଶ) − ^^ − ^^ℎ^^^^^^^^^^^^^^^^^^^^^^ + ^^ଶ^^Equation 2 (^^^^^)ଷ − ^^^^ − ^^^^ + ^^^^ − ^^ℎ^^^^^^^^^^^^^^^^^^^^^^ → (^^^^^)ଷ − ^^^^ − ^^ − ^^ℎ^^^^^^^^^^^^^^^^^^^^^^ + ^^ଶ^^Equation 3(^^^^^)ଶ − ^^^^(^^ଶ) − ^^^^ + ^^^^ − ^^ℎ^^^^^^^^^^^^^^^^^^^^^^ → (^^^^^)ଶ − ^^^^(^^ଶ) − ^^ − ^^ℎ^^^^^^^^^^^^^^^^^^^^^^ + ^^ଶ^^Equation 4

[0107] Equations 1 to 4 relate to examples of embodiments that are sol-gel specific, comprising a substrate, a sol-gel process, and adhesion with photocatalytic particles for use within a photocatalytic cartridge. Within Equations 1 and 2, the ‘M’ refers to the use of a metal within the reaction and are general equations that would cover multiple types of metal oxide sol-gel reactions. Within Equations 3 and 4, a silicon ‘Si’ is specifically used within the sol-gel process. The inventors note that above Equations 1 to 4 are general in supporting the embodiments within the presentdisclosure, and further equations, beyond those disclosed herein, are envisaged to cover alternative chemical components that may be utilised within the embodiments and method steps disclosed. Furthermore, the inventors note that the Photocatalyst within Equations 3 and 4 above, may utilise a separate acid or base to facilitate the reaction. In this reaction, the pH of the solution, comprising the Photocatalyst, will determine the resultant sol-gel structure. The Photocatalyst may change the pH of the solution, however, the pH of the acid or base that is added will have the most significant effect, and the sol-gel material, is in a sheet / layer / film form or in a spherical form.

[0108] In one embodiment, the photocatalytic particles 30 may be considered a photocatalyst powder. The photocatalyst powder may be obtained in its powdered or ‘dust’ form. In an alternative embodiment, a sheet of photocatalyst may be crushed, agitated, or comminuted to produce the photocatalytic particles 30. The crushing, agitating, or comminuting of the sheet of the photocatalyst may be performed by a mill or the like, such that the sheet is turned into particles that may be adhered to a surface of a substrate 20, where the substrate 20 may be any one or more of a polymer, a polymeric layer, a polymeric sphere, a glass bead, or the like already discussed herein. In a further embodiment, in the instance that the substrate 20 is formed by the sol-gel process, a sheet of photocatalyst may be crushed, agitated, or comminuted into particles that are subsequently added to the sol-gel process, then adhered to the substrate 20 using an adhesive, such as a glue product or another sol-gel. This is particularly illustrated in process flow diagrams in Figures 14, 15, 19 and 20. The use of a sol-gel may advantageously improve adhesion of photocatalytic particles 30 onto a surface of the substrate 20. This is due to a reaction that occurs between the sol-gel and the surface of the substrate 20 that forms covalent bonds between the sol-gel and the surface resulting in an improved adhesion surface for the photocatalytic particles 30.

[0109] In one embodiment, at the stage of installing the cover 14 onto the frame 13 to define the container 12 for the substrate 20, where the substrate 20 comprised any one or more of the plurality of spheres, such as glass beads, or the polymeric spheres, or hollow spheres, where the spheres are coated with the photocatalytic particles 30 and are fluid or mobile within the container 12. In this embodiment, installing the cover 14 secures the spheres, as a fixed structure 70 within the container 12 that is configured to facilitate exposure of photocatalytic particles 30 to solar radiation 200 when the replaceable photocatalytic cartridge 10 is within the receiving portion 110 of the reactor 100. In this embodiment, the fixed structure 70 may be a fixed porous structure within the container 12 that enables gases and liquids within the reactive environment 120 of the reactor 100 to flow therebetween. One example is to have the structure 70, within the cartridge 10, in a tightly packed arrangement comprising more than one substrate 20, where each substrate 20 comprises the plurality of spheres.

[0110] In an alternative to the above, where the substrate 20 comprises the plurality of spheres, which are coated with the photocatalytic particles 30, and the substrate 20 is fluid or mobile within the container 12, this may be understood as an arrangement that permits the coated spheres 20 to circulate, or flow, within the container 12, to advantageously permit for greater exposure (i.e. maximise exposure) to solar radiation 200 due to an increased surface area of the spheres 20, and thus photocatalytic particles 30, being exposed to the solar radiation 200. In this embodiment, the plurality of spheres coated with the photocatalytic particles 30 are fluid or mobile within the container 12 due to a flow of gases and / or liquids within the reactive environment 120 of the reactor 100, that flows between and / or through the spheres. The inventors note that there are benefits to both a fixed, or tightly packed, arrangement of the substrate 20, where it comprises the plurality of spheres, within the replaceable photocatalytic cartridge 10, and also a fluid arrangement of the same within the cartridge 10. The inventors also note that by being fluid or mobile, the substrate 20 facilitates the detachment of hydrogen and oxygen bubbles generated from H2O during the photocatalytic reaction. All these arrangements, or configurations, of the plurality of spheres 20 comprising the photocatalytic particles 30 within the cartridge 10 are within the scope of the present disclosure.

[0111] In an alternative embodiment, the plurality of spheres 20 comprising (or coated with) the photocatalytic particles 30 may be encapsulated within a porous film, or a breathable material, that contains the spheres 20 therein in a fluid or mobile state so as to form the substrate within the container 12 of the photocatalytic cartridge 10. Within this embodiment, it will be appreciated that as the porous film, or the breathable material, encapsulates the entirety of the coated plurality of spheres 20, there is no need for the cover 14, or the like, to the frame 13 to define the container 12 and contain and / or secure the coated spheres 20 to form the replaceable photocatalytic cartridge 10.

[0112] In one embodiment, one or more sides of the frame 13 and the cover 14 are porous to permit the flow of gas and liquid therethrough. The gases may be H2and O2, and the liquid may be H2O, all of which may be present within the reactor that the cartridge 10 is in use.

[0113] Below is a first example method for producing a replaceable photocatalytic cartridge 10 for use in a reactor 100, which may comprise the steps of: a) providing at least one substrate 20; b) heating the substrate 20 to an adhering temperature; c) contacting the substrate 20 to photocatalytic particles 30 to adhere the photocatalytic particles 30 to the substrate 20;d) allowing the photocatalytic particles 30 to bind onto the substrate 20 and form a coating on the substrate 20 (and thus form the coated substrate 20a); e) depositing the coated substrate 20a into a container 12 to form the replaceable photocatalytic cartridge 10, wherein the contained coated substrate 20a is adapted to participate in a photocatalytic reaction with H2O and solar radiation 200 within the reactor 100, and in combination the replaceable photocatalytic cartridge 10 and the coated substrate 20a are configured to facilitate exposure of the photocatalytic particles 30 to solar radiation 200 in the reactor 100; and f) inserting the replaceable photocatalytic cartridge 10 into a receiving portion 110 of the reactor 100.

[0114] In the first example method, at step (b), in the instance that the substrate 20 is sol-gel coated, the sol-gel coated substrate is maintained at an appropriate temperature and humidity. In an example, the sol-gel coated substrate may be maintained at a temperature of approximately 70 °C and a corresponding approximate humidity of 43%. At step (c) the sol-gel coated substrate 23 contacts the photocatalytic particles to adhere the photocatalytic particles 30 to the sol-gel coated substrate 23 and thus form the coated substrate 20a at step (e).

[0115] Also in the first example method, at step (e) the plurality of spheres coated with the photocatalytic particles 30 are fluid or mobile within the container 12, and in use, fluidity or mobility of the coated spheres is configured to facilitate exposure of the photocatalytic particles 30 to solar radiation 200. Additionally, the inventors note that by being fluid or mobile within the container 12, the coated spheres 20a aid in hydrogen and oxygen bubble detachment from the surface of the coated spheres 20a, as due to their fluidity / mobility, the coated spheres 20a advantageously dislodge / detach hydrogen / oxygen bubbles that are formed by splitting H2O that may be ‘sitting on’ the coated spheres 20a. In an alternative, also at step (e), the plurality of spheres coated with the photocatalytic particles 30 are spaced to form a fixed porous structure 70 within the container 12 that enables gases and liquids within the reactor 100 to flow therebetween.

[0116] Below is a second example method for producing a replaceable photocatalytic cartridge 10 for use in a reactor 100, which may comprise the steps of: a) providing at least one substrate 20 comprising a plurality of spheres; b) heating the plurality of spheres 20 to an adhering temperature;c) contacting the heated spheres 20 to photocatalytic particles 30 to adhere the photocatalytic particles 30 to the spheres 20; d) allowing the photocatalytic particles 30 to bind onto the spheres 20 and form a coating on the spheres 20; e) depositing the coated spheres 20a into a container 12 to form the replaceable photocatalytic cartridge 10, wherein the contained coated spheres 20a are adapted to participate in a photocatalytic reaction with H2O and solar radiation 200 within the reactor 100 that maximise exposure of the photocatalytic particles 30 to solar radiation 200; and f) inserting the replaceable photocatalytic cartridge 10 into a receiving portion 110 of the reactor 100.

[0117] Below is a third example method for producing a replaceable photocatalytic cartridge 10 for use in a reactor 100, which may comprise the steps of: a) providing at least one substrate 20 comprising a plurality of spheres, wherein the spheres are glass spheres; b) heating the glass spheres 20 to an adhering temperature; c) contacting the heated glass spheres 20 to photocatalytic particles 30 to adhere the photocatalytic particles 30 to the glass spheres 20; d) allowing the photocatalytic particles 30 to bind onto the spheres 20 and form a coating on the glass spheres 20; e) depositing the coated glass spheres 20a coated with photocatalytic particles into a container 12 to form the replaceable photocatalytic cartridge 10, wherein the contained coated substrate 20a is adapted to participate in a photocatalytic reaction with H2O and solar radiation 200 within the reactor 100 that maximise exposure of the photocatalytic particles 30 to solar radiation 200; and f) wherein the coated glass spheres 20a are fluid or mobile within the container 12 of the replaceable photocatalytic cartridge 10 so as to optimise exposure of photocatalytic particles 30 to solar radiation 200 incident to the reactor 100.

[0118] Below is a fourth example method for producing a replaceable photocatalytic cartridge 10 for a reactor 100, which may comprise the steps of: a) providing at least one polymeric layer 20; b) heating the polymeric layer 20 to an adhering temperature, the adhering temperature between a softening temperature and a melting temperature of the polymeric layer 20; c) contacting the heated polymeric layer 20 to photocatalytic particles 30 to adhere the photocatalytic particles 30 to the polymeric layer 20; d) allowing the photocatalytic particles 30 to bind onto the polymeric layer 20 and form a coating on the polymeric layer 20; e) depositing the coated polymeric layer 20a a frame 13 of the replaceable photocatalytic cartridge 10; f) installing a cover 14 to the frame 13, wherein the polymeric layer 20 therein forms a structure 70 that optimises exposure of photocatalytic particles 30 to solar radiation 200 incident to the reactor 100; g) inserting the replaceable photocatalytic cartridge 10 within a receiving portion 110 of the reactor 100; and h) wherein the contained coated polymeric layer 20a is adapted to participate in a photocatalytic reaction with H2O and solar radiation 200 within the reactor 100 to photocatalytically split the H2O into hydrogen and oxygen. i) Optional step of removing the replaceable photocatalytic cartridge 10 from the reactor 100, once depleted, damaged, or no longer efficient in photocatalytically splitting H2O, without disrupting the continuous operation of the reactor 100.

[0119] In the third example method, pore spaces between the plurality of spheres may enable flow of gases and fluids therethrough.

[0120] Additionally, also in the fourth example method, the inventors estimate that the size and distribution of the pore spaces within the polymeric layer, which may be a composite material, is within a range between 4 to 20 microns.

[0121] In any one of the example methods provided above, and other references throughout the present disclosure, it will be appreciated that ‘polymeric layer’ may alternatively be considered a ‘polymeric sheet’, or a ‘polymer sheet’.

[0122] In one embodiment, not illustrated, in addition to the replaceable photocatalytic cartridge device 10 and methods disclosed, the present disclosure also relates to a method of forming a replaceable photocatalytic cartridge for use in a reactor. The inventors envisage that this method of “forming” to cover instances where the disclosed photocatalytic cartridge 10 is produced via any general process or manufacturing, such as, however not limited to, assembling, shaping, or constructing the cartridge, from its constituent parts or materials, and may comprise both physical and chemical processes for “forming” the cartridge 10. It will be appreciated that the “formed” cartridge 10 is insertable, or receivable, within a receiving portion 110 of a reactor 100, and in use, the cartridge 10 is adapted to participate in a photocatalytic reaction with H2O and solar radiation 200 within the reactor 100 that maximises exposure of the photocatalytic particles 30 to solar radiation 200.

[0123] The inventors envisage that one example method of the above embodiment may be, a method of forming a replaceable photocatalytic cartridge for use in a reactor, the method comprising: a) preparing at least one substrate; b) applying photocatalytic particles to the substrate with a binder to adhere the photocatalytic particles to the substrate; c) allowing the photocatalytic particles to bind onto the substrate and form a coating on the substrate; d) depositing the coated substrate into a container defined to form the replaceable photocatalytic cartridge, wherein the contained coated substrate is adapted to participate in a photocatalytic reaction with H2O and solar radiation within the reactor, and in combination the formed photocatalytic cartridge and the coated substrate are configured to facilitate exposure of the photocatalytic particles to solar radiation in the reactor; and e) inserting the replaceable photocatalytic cartridge into a receiving portion of the reactor.

[0124] Within the above exemplary method, at step b), it may be understood that the photocatalytic particles are applied, deposited, attached, or integrated with the substrate. Within this step, the binder may be an adhesive means, that may be either one or, or both of, a chemical and / or physical adhesion of the photocatalytic particles to the substrate. The inventors envisage examples ofthe binder may include any one or more of, sol-gel adhesives, chemical linkers (e.g. APTES), or the like.

[0125] It will be appreciated that, in addition to the methods and the replaceable photocatalytic cartridge 10 device disclosed, the present disclosure also relates to a composition. Without repeating all of the previous disclosure, the composition comprises: photocatalytic particles activated by light, the photocatalytic particles being capable of photocatalytically splitting H2O into hydrogen and oxygen; particles of a polymer comprising a size (i.e. diameter or width) between 0.015mm to 20 mm; wherein the photocatalytic particles are adhered to a surface of the polymer particles by heating the polymer particles to an adhering temperature between 70°C to 200°C and contacting the photocatalytic particles, and agitating the polymer particles comprising the photocatalytic particles adhered thereto to create the composition; and wherein, in use, the composition, when applied to a surface optimises exposure of the photocatalytic particles to solar radiation incident to the surface. The inventors would like to note that the adhering temperature range may be wider than 70°C to 200°C above, and that other adhering temperature ranges may be possible for alternate substrate constituents and photocatalytic particles beyond those discussed herein.

[0126] The replaceable photocatalytic cartridge 10, of any one of the above embodiments, when in use within a reactor 100, can be monitored for its efficiency based on H2and O2production rates and observing delamination to determine when the cartridge 10 is no longer efficient and needs replacement with a new replaceable photocatalytic cartridge 10 within the reactor 100.

[0127] The replaceable photocatalytic cartridge 10 of any one of the above embodiments is a removable, replaceable, component, or element, of a reactor 100, or reactor cell. Advantageously, the replaceable photocatalytic cartridge 10 of any one of the embodiments, may be replaced, once depleted, damaged, or no longer efficient in photocatalytically splitting H2O, without disrupting the continuous operation of the reactor.

[0128] Another advantage of the replaceable photocatalytic cartridge 10 of any one of the above embodiments is that it is more physically robust to handle and produce when compared to existing photocatalyst sheets, or the like, which are fragile to handle and often difficult to remove / install, as presently utilised within reactors.

[0129] Another advantage of the replaceable photocatalytic cartridge 10 of any one of the above embodiments is that the reactor 100 may not require complete disassembly in order to replace the cartridge 10, once the photocatalytic particles 30 coated on the substrate 20 of the cartridge 10 are no longer efficient in photocatalytically splitting H2O. Rather, the reactor 100 may only requireminimal disassembly, or minor reconfiguration, in order to replace the replaceable photocatalytic cartridge 10.

[0130] A further advantage of the replaceable photocatalytic cartridge 10 of any one of the above embodiments is that the disclosed method presents an economical and simple solution to produce the cartridge 10 capable of photocatalytically splitting H2O, when compared to existing photocatalysts and existing photocatalytic water splitting reactors.

[0131] Yet a further advantage is that, due to several suitable substrates 20, that may be coated 20a, and utilised by any one of the disclosed replaceable photocatalytic cartridge 10 embodiments, a given substrate 20 may be selected based on availability, viability, and cost thereof. Coupled with the simplicity of production by way of the cartridge 10 being a distinct, removable and replaceable, product to the reactor 100, through experimentation and results, the inventors summarise that the disclosed replaceable photocatalytic cartridge 10, and methods of producing the same, advantageously: 1. Provide for an efficient, cost-effective, and easy to maintain solution for replacing photocatalysts within photocatalytic water splitting reactors (PWS reactors); 2. Provides for a porous and / or mobile photocatalyst (i.e. disclosed substrate coated with photocatalytic particles) that enables the flow of gases and liquids present within PWS reactors therethrough; and 3. Increases the number of reactive interfaces (i.e. maximises photocatalytically active sites) between solar radiation (i.e. light), photocatalyst (i.e. the replaceable photocatalytic cartridge), and H2O within PWS reactors.

[0132] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that such prior art forms part of the common general knowledge.

[0133] It will be understood that the terms “comprise” and “include” and any of their derivatives (e.g. comprises, comprising, includes, including) as used in this specification, and the claims that follow, is to be taken to be inclusive of features to which the term refers, and is not meant to exclude the presence of any additional features unless otherwise stated or implied.

[0134] In some cases, a single embodiment may, for succinctness and / or to assist in understanding the scope of the disclosure, combine multiple features. It is to be understood that in such a case, these multiple features may be provided separately (in separate embodiments), or in any other suitable combination. Alternatively, where separate features are described in separate embodiments, these separate features may be combined into a single embodiment unless otherwise stated or implied. This also applies to the claims which can be recombined in any combination. That is a claim may be amended to include a feature defined in any other claim. Further a phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover: a, b, c, a-b, a-c, b-c, and a-b-c.

[0135] It will be appreciated by those skilled in the art that the disclosure is not restricted in its use to the particular application or applications described. Neither is the present disclosure restricted in its preferred embodiment with regard to the particular elements and / or features described or depicted herein. It will be appreciated that the disclosure is not limited to the embodiment or embodiments disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the scope as set forth and defined by the following claims.

Claims

CLAIMS 1. A replaceable photocatalytic cartridge for use in a reactor, the cartridge comprising; a container; a substrate within the container, wherein the substrate comprises a coating of photocatalytic particles adhered to its surface; wherein, in use, the replaceable photocatalytic cartridge is configured to be removably inserted into a receiving portion of the reactor such that: the coated substrate is adapted to participate in a photocatalytic reaction with H2O and solar radiation within the reactor; and wherein in combination the replaceable photocatalytic cartridge and the coated substrate are configured to facilitate exposure of the photocatalytic particles to solar radiation and detachment of hydrogen and oxygen bubbles generated from H2O during the photocatalytic reaction from the coated substrate.

2. The replaceable photocatalytic cartridge of claim 1, wherein the substrate comprises any one of a plurality of spheres, a plate, a sheet, a slide, a film, a particulate material, a material with a mesh structure, or a sol-gel product, wherein any one or more of these comprise the coating of photocatalytic particles adhered thereto.

3. The replaceable photocatalytic cartridge of claim 2, wherein the substrate comprises the plurality of spheres, wherein each sphere is coated with the photocatalytic particles to increase the surface area of the photocatalytic particles which are adhered to the coated substrate.

4. The replaceable photocatalytic cartridge of claim 3, wherein the plurality of spheres coated with the photocatalytic particles maximise photocatalytically active sites on the coated substrate exposed to solar radiation.

5. The replaceable photocatalytic cartridge of either one of claims 3 or 4, wherein the plurality of spheres coated with the photocatalytic particles are fluid or mobile within the container, and in use, fluidity or mobility of the coated spheres is configured to facilitate exposure of the photocatalytic particles to solar radiation and detachment of hydrogen and oxygen bubbles generated from H2O during the photocatalytic reaction from the coated spheres.

6. The replaceable photocatalytic cartridge of claim 5, wherein the plurality of spheres coated with the photocatalytic particles are fluid or mobile within the container due to a flow of gases and / or liquids within the reactor that flows between and / or through the coated spheres.

7. The replaceable photocatalytic cartridge of either one of claims 3 or 4, wherein the plurality of spheres coated with the photocatalytic particles are spaced to form a fixed porous structure within the container that enables gases and liquids within the reactor to flow therebetween.

8. The replaceable photocatalytic cartridge of any one of claims 3 to 7, wherein the spheres are either formed or coated with a sol-gel.

9. The replaceable photocatalytic cartridge of claim 8, wherein the sol-gel increases durability of the spheres and aids in the adhesion of the photocatalytic particles.

10. The replaceable photocatalytic cartridge of any one of claims 3 to 9, wherein the spheres are a polymeric material, a glass material, or a sol-gel material.

11. The replaceable photocatalytic cartridge of any one of claims 3 to 10, wherein the spheres are sized between 0.015mm to 20mm.

12. The replaceable photocatalytic cartridge of any one of the preceding claims, wherein the container comprises a porous portion, wherein, in use, the porous portion permits the flow of gas and liquid therethrough to the coated substrate.

13. The replaceable photocatalytic cartridge of any one of the preceding claims, wherein the container comprises a frame and a cover that cooperate to define the container, wherein the cover is a fritted glass.

14. The replaceable photocatalytic cartridge of either one of claims 1 or 2, wherein the substrate comprises a sol-gel product and the photocatalytic particles are embedded within the sol-gel product and / or adhered on a surface of the sol-gel product.

15. The replaceable photocatalytic cartridge of either one of claims 1 or 2, wherein the container further comprises a suspension of photocatalytic particles.

16. A method of producing a replaceable photocatalytic cartridge for use in a reactor, the method comprising: (a) providing at least one substrate; (b) heating the substrate to an adhering temperature; (c) contacting the substrate to photocatalytic particles to adhere the photocatalytic particles to the substrate;(d) allowing the photocatalytic particles to bind onto the substrate and form a coating on the substrate; (e) depositing the coated substrate into a container to form the replaceable photocatalytic cartridge, wherein the contained coated substrate is adapted to participate in a photocatalytic reaction with H2O and solar radiation within the reactor, and in combination the replaceable photocatalytic cartridge and the coated substrate are configured to facilitate exposure of the photocatalytic particles to solar radiation in the reactor; and (f) inserting the replaceable photocatalytic cartridge into a receiving portion of the reactor.

17. The method of claim 16, wherein at step (a), the at least one substrate comprises any one of a plurality of spheres, a plate, a sheet, a slide, a film, a particulate material, a material with a mesh structure, or a sol-gel product, wherein the plurality of spheres, the plate, the sheet, the slide, the film, or the material with a mesh structure is a polymeric or glass material.

18. The method of claim 16, wherein at step (a), the substrate is also coated with a sol-gel using a process that includes: i. preparing a sol comprising a solvent, and one or more precursor compounds; ii. applying the sol to the substrate; iii. allowing the sol to undergo gelation and form a gel coating on the substrate; and iv. curing the gel to form a solidified coating adhered to the substrate.

19. The method of claim 18, wherein at step (b) the sol-gel coated substrate is maintained at an appropriate temperature and humidity, and at step (c) the sol-gel coated substrate contacts the photocatalytic particles to adhere the photocatalytic particles to the sol-gel coated substrate and form the coated substrate deposited at step (e).

20. The method of claim 19, wherein the sol-gel coating aids in the adhesion of the photocatalytic particles to the substrate and increases the durability of the substrate.

21. The method of claim 17, wherein the substrate comprises the plurality of spheres, wherein each sphere is coated with the photocatalytic particles to increase the surface area of the photocatalytic particles which are adhered to the coated substrate and maximise photocatalytically active sites on the coated substrate exposed to solar radiation.

22. The method of claim 21, wherein at step (e), the plurality of spheres coated with the photocatalytic particles are fluid or mobile within the container, and in use, fluidity or mobility of the coated spheres is configured to facilitate exposure of the photocatalytic particles to solar radiation anddetachment of hydrogen and oxygen bubbles generated from H2O during the photocatalytic reaction from the coated spheres.

23. The method of claim 21, wherein at step (e), the plurality of spheres coated with the photocatalytic particles are spaced to form a fixed porous structure within the container that enables gases and liquids within the reactor to flow therebetween.

24. A method of forming a replaceable photocatalytic cartridge for use in a reactor, the method comprising: (a) preparing at least one substrate; (b) applying photocatalytic particles to the substrate with a binder to adhere the photocatalytic particles to the substrate; (c) allowing the photocatalytic particles to bind onto the substrate and form a coating on the substrate; (d) depositing the coated substrate into a container to form the replaceable photocatalytic cartridge, wherein the contained coated substrate is adapted to participate in a photocatalytic reaction with H2O and solar radiation within the reactor, and in combination the replaceable photocatalytic cartridge and the coated substrate are configured to facilitate exposure of the photocatalytic particles to solar radiation in the reactor; and (e) inserting the replaceable photocatalytic cartridge into a receiving portion of the reactor.

25. A replaceable photocatalytic cartridge for use in a reactor, the cartridge comprising: a container; a substrate within the container, wherein the substrate comprises a coating of photocatalytic particles adhered to its surface; wherein, in use, the replaceable photocatalytic cartridge is configured to be removably inserted into a receiving portion of the reactor such that: the coated substrate is adapted to participate in a photocatalytic reaction with H2O and solar radiation within the reactor; and wherein in combination the replaceable photocatalytic cartridge and the coated substrate are configured to facilitate exposure of the photocatalytic particles to solar radiation.

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