WO2024163792A1

WO2024163792A1 - Plasmonic photonic technology for destruction of pollutants in fluids

Info

Publication number: WO2024163792A1
Application number: PCT/US2024/014071
Authority: WO
Inventors: Lovely GOSWAMI
Original assignee: Applied Photonix, Llc
Priority date: 2023-02-01
Filing date: 2024-02-01
Publication date: 2024-08-08

Abstract

A material composition for detoxifying a fluid includes a photocatalyst and nanoparticles of a non-oxidizing metal alloy, such as plasmonic nanoparticles. An article for purifying a fluid includes a substrate having a first surface opposite a second surface and a coating over one of the first surface and the second surface. The coating includes a photocatalyst and plasmonic nanoparticles. A system for purifying a fluid includes a housing defining a volume, a light source removably coupled to the housing configured to emit radiation at a predetermined frequency, a substrate positioned adjacent the light source, the substrate including plasmonic nanoparticles configured to emit radiation at the predetermined frequency, and a volume defined between the light source and the substrate configured to receive the fluid.

Description

PLASMONIC PHOTONIC TECHNOLOGY FOR DESTRUCTION OF POLLUTANTS IN FLUIDS

CROSS-REFERNCE TO RELATED PATENT APPLICATIONS

[0001] The present application claims the benefit of United States provisional Patent Application Serial No. 63/442,676, filed February 1, 2023, the entirety of which is incorporated herein by reference.

TECHNICAL FIELD

[0002] The present disclosure relates to material compositions and systems for destruction of pollutants in fluids, such as gases or liquids. The pollutants may include, but are not limited to, biological and chemical pollutants.

BACKGROUND

[0003] Air quality is frequently compromised by pollutants, such as viral, bacterial, and volatile organic chemical (VOC) pollutants. Reducing pollutants in the air is beneficial for human and environmental health.

[0004] Accordingly, those skilled in the art continue research and development in the field of improving air quality.

SUMMARY

[0005] This summary is intended merely to introduce a simplified summary of some aspects of one or more implementations of the present disclosure. Further areas of applicability of the present disclosure will become apparent from the detailed description provided hereinafter. This summary is not an extensive overview, nor is it intended to identify key or critical elements of the present teachings, nor to delineate the scope of the disclosure. Rather, its purpose is merely to present one or more concepts in simplified form as a prelude to the detailed description below.

[0006] Applicants have discovered material compositions for purifying a fluid.

[0007] In one example, the material composition includes a photocatalyst and nanoparticlcs of a non-oxidizing metal alloy. [0008] In one example, the non-oxidizing metal alloy comprises a metal and an electron scavenger. In one example, the nanoparticlcs arc plasmonic nanoparticlcs. In one example, the photocatalyst comprises one or more of TiCh, ZnO, SnCh, CdS, WO3. In one example, the photocatalyst has an average particle size ranging from about 20 nm to about 1000 nm. In one example, the nanoparticles of a non-oxidizing metal alloy have an average particle size ranging from about 30nm to about 70nm.

[0009] In one example, the material composition is configured to emit radiation at a frequency having a wavelength ranging from about 350nm to about 420nm.

[00010] In one example, the material composition includes a surfactant. In one example, the surfactant is an alcohol.

[00011] Also disclosed is an article for purifying a fluid.

[00012] In one example, the article includes a substrate having a first surface opposite a second surface and a coating over one of the first surface and the second surface. The coating includes a photocatalyst and plasmonic nanoparticles.

[00013] In one example, the substrate includes a fibrous material, fabric, metal, cellulosic material, ceramic, or a paint. In one example, the photocatalyst comprises one or more of TiCh, ZnO, SnO2, CdS, WO3. In one example, the photocatalyst has an average particle size ranging from about 20 nm to about 1000 nm. In one example, the plasmonic nanoparticles have an average particle size ranging from about 30nm to about 70nm. In one example, the plasmonic nanoparticles are non- oxidizable. In one example, the plasmonic nanoparticles comprise one or more metals, semiconductor, and metalloid. In one example, the plasmonic nanoparticles comprise one or more of gold, platinum, silver, copper, zinc, and nickel. In one example, the plasmonic nanoparticles comprise one or more of silicon, germanium, selenium, and gallium. In one example, the plasmonic nanoparticles comprise one or more of boron, silicon, and germanium.

[00014] Also disclosed is a system for purifying a fluid.

[00015] In one example, the system includes a housing and a light source removably coupled to the housing, the light source configured to emit radiation at a predetermined frequency. The system also includes a substrate positioned between the housing and the light source, the substrate including plasmonic nanoparticles configured to emit radiation at the predetermined frequency, and a volume defined by the housing configured to receive the fluid.

[00016] In one example, the system includes a fan positioned configured to draw the fluid through the volume and past the substrate. In one example, the fluid is air. In one example, the radiation has a wavelength ranging from about 350nm to about 420nm. In one example, the plasmonic nanoparticles have an average particle size ranging from about 1/2 to about 1/15 the size of the wavelength of the radiation emitted from the light source. In one example, the plasmonic nanoparticles have an average particle size ranging from about 30nm to about 70nm. In one example, the plasmonic nanoparticles are non-oxidizable. In one example, the photocatalyst comprises one or more of TiO2, ZnO, SnC>2, CdS, WO3. In one example, the photocatalyst has an average particle size ranging from about 20 nm to about 1000 nm. In one example, the plasmonic nanoparticles comprise one or more metals, semiconductor, and metalloid. In one example, the plasmonic nanoparticles comprise one or more of gold, platinum, silver, copper, zinc, and nickel. In one example, the plasmonic nanoparticles comprise one or more of silicon, germanium, selenium, and gallium. In one example, the plasmonic nanoparticles comprise one or more of boron, silicon, and germanium.

[00017] Also disclosed is an air purifier.

[00018] In one example, the air purifier includes a filter media coated with a coating. The coating includes a photocatalyst and plasmonic nanoparticles. The coating may further include a surfactant, such as an alcohol.

[00019] In one example the plasmonic nanoparticles have an average particle size ranging from about 30nm to about 70nm. In one example, the plasmonic nanoparticles are non-oxidizable.

[00020] In one example, the photocatalyst comprises one or more of TiCh, ZnO, SnO2, CdS, WO3. In another example, the photocatalyst has an average particle size ranging from about 20 nm to about 1000 nm.

[00021] In one example, the plasmonic nanoparticles comprise one or more metals, semiconductor, and metalloid. In another example, the plasmonic nanoparticles comprise one or more of gold, platinum, silver, copper, zinc, and nickel. In another example, the plasmonic nanoparticles comprise one or more of silicon, germanium, selenium, and gallium. In yet another example, the plasmonic nanoparticles comprise one or more of boron, silicon, and germanium. [00022] Also disclosed is a method for manufacturing an article for purifying a fluid.

[00023] In one example, the method includes providing a substrate having a first surface opposite a second surface, mixing a photocatalyst with plasmonic nanoparticles to yield a coating composition, applying the coating composition to one of the first surface and the second surface of the substrate, and drying the coating composition to yield a purifying coating. In one example, the method further includes mixing a surfactant with the photocatalyst and plasmonic nanoparticles. In one example, the surfactant is an alcohol.

[00024] In one example, the substrate is a filter. In another example, the substrate comprises a fibrous material, fabric, metal, cellulosic material, ceramic, or a paint. In one example, the photocatalyst comprises one or more of TiO2, ZnO, SnCE, CdS, WO3. In one example, the photocatalyst has an average particle size ranging from about 20 nm to about 1000 nm.

[00025] In one example, the plasmonic nanoparticles have an average particle size ranging from about 30nm to about 70nm. In one example, the plasmonic nanoparticles are non-oxidizable. In one example, the plasmonic nanoparticles comprise one or more metals, semiconductor, and metalloid. In one example, the plasmonic nanoparticles comprise one or more of gold, platinum, silver, copper, zinc, and nickel. In another example, the plasmonic nanoparticles comprise one or more of silicon, germanium, selenium, and gallium. In yet another example, the plasmonic nanoparticles comprise one or more of boron, silicon, and germanium.

[00026] Further areas of applicability of the present disclosure will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred examples of the disclosure, are intended for purposes of illustration only and are not intended to limit the scope of the disclosure.

DESCRIPTION OF THE DRAWINGS

[00027] The detailed description of the disclosure will be better understood when read in conjunction with the appended drawings. It should be understood, however, that the disclosure is not limited to the precise arrangements and instrumentalities of the examples shown in the drawings.

[00028] FIG. 1 is a schematic of a substrate coated with a material composition; [00029] FIG. 2 is a schematic of a system for purifying a fluid;

[00030] FIG. 3 is a graph illustrating material reaction rates for the destruction of organic chemicals; and

[00031] FIG. 4 is a graph illustrating a graph illustrating material reaction rates for the destruction of organic chemicals.

DETAILED DESCRIPTION

[00032] The following description of the preferred example(s) is merely exemplary in nature and is in no way intended to limit the disclosure, its application, or uses.

[00033] As used throughout, ranges are used as shorthand for describing each and every value that is within the range. Any value within the range can be selected as the terminus of the range. In addition, all references cited herein are hereby incorporated by referenced in their entireties. In the event of a conflict in a definition in the present disclosure and that of a cited reference, the present disclosure controls.

[00034] The description of illustrative examples according to principles of the present disclosure is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. In the description of examples of the disclosure disclosed herein, any reference to direction or orientation is merely intended for convenience of description and is not intended in any way to limit the scope of the present disclosure. Relative terms such as “lower,” “upper,” “horizontal,” “vertical,” “above,” “below,” “up,” “down,” “top,” and “bottom” as well as derivatives thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description only and do not require that the apparatus be constructed or operated in a particular orientation unless explicitly indicated as such.

[00035] Terms such as “attached,” “affixed,” “connected,” “coupled,” “interconnected,” and similar refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise. Moreover, the features and benefits of the disclosure are illustrated by reference to the exemplified examples. Accordingly, the disclosure expressly should not be limited to such exemplary examples illustrating some possible non- limiting combination of features that may exist alone or in other combinations of features; the scope of the disclosure being defined by the claims appended hereto.

[00036] Unless otherwise specified, all percentages and amounts expressed herein and elsewhere in the specification should be understood to refer to percentages by weight. The amounts given are based on the active weight of the material. According to the present application, the term “about” means +/- 5% of the reference value. According to the present application, the term “substantially free” means less than about 0.1 wt. % based on the total of the referenced value.

[00037] The present disclosure is directed to materials, articles, and systems for removing pollutants from a fluid, such as air. Many existing air cleaning technologies focus on filtration of particulate matter, such as HEPA filters. HEPA filters cannot effectively remove viruses and VOCs.

[00038] In recent years, photocatalytic oxidation (PCO) and photo-electrochemical oxidation (PECO) technologies have been developed. PCO overcomes the inability of HEPA filters against viruses and VOCs, however, the PCO process is slow and has a low quantum efficiency. PCO is a photocatalytic technology designed to disinfect and detoxify indoor air. In PCO technology, when light of a specific wavelength is absorbed on a semiconductor, if the energy of the photon is more than the bandgap of the semiconductor, it frees up an electron from the semiconductor, which leaves a “hole” in the semiconductor material. If a water molecule is present at the site of the semiconductor in the form of a negative charged hydroxyl ion and a positive charged hydrogen ion, the hydroxyl ion gives up its electron to fill the “hole”, and in the process becomes a hydroxyl “free radical”. The hydroxyl free radical then oxidizes any organic chemical in the presence of oxygen. The PCO technology is effective, but can be slow.

[00039] PECO has overcome the shortcomings of HEPA filters as well as PCO technology. In PECO technology, a metallic path is provided in the form of a metal mesh for the free electrons to keep them away from the holes, which improves the quantum efficiency of the photocatalytic oxidation process. This improvement increased the efficiency and speed of the photocatalytic oxidation process by orders of magnitude.

[00040] The present disclosure is directed to improved materials and systems for purifying a fluid. In one example, the present disclosure includes a unique mixture of a photocatalyst and metal alloy nanoparticles that enhances the performance of the photocatalyst in destroying viruses and other organic contaminants.

[00041] In one or more examples, the photocatalyst using a metal oxide photocatalyst and the metal alloy nanoparticles are be combined in a way that enhances and accelerates the chemical reactions that destroy viruses, bacteria, mold, spores, and other microorganisms, Volatile Organic Chemicals (VOCs) emitted from many indoor materials such as paints, coatings and carpets as well as cooking and allergens, such as, droppings of dust mites and cockroaches, etc.

[00042] The present disclosure described herein has several advantages over conventional PECO technology. First, the present disclosure described herein utilizes a plasmonic photonic technology, which enhances the effectiveness and speed of the photocatalytic process by more than 50% over the conventional PECO technology.

[00043] When electromagnetic energy of a light wave incident on a nanoparticle pulls an electron away from the nucleus, the nucleus pulls the electron back. The electron moves back and forth like a wave creating Surface Plasmon Polaritons also known as EM excited plasmons. If the natural frequency of the plasmons matches the frequency of the incoming electromagnetic radiation, resonance occurs, which allows the nanoparticles to absorb more photons than typical catalytic nanoparticles. This process is called Plasmonic Photonic process, and the nanoparticles causing this process are Plasmonic nanoparticles.

[00044] When a metal becomes oxidized, the performance of the PECO process may be compromised. Therefore, a thin non-porous layer coating of a material, such as silicon oxide, over the noble metal may be used to protect the noble metal from oxidation. However, the net effect of the additional layer of silicon oxide or any other material, no matter how thin, is to reduce the performance of the coated metal.

[00045] It is known that a layer of plasmonic particles coated on a photocatalyst and its effect on enhancing the performance of photocatalytic oxidation process. However, it IS also known that the performance degrades in as little as 2-3 cycles because the plasmonic particles become oxidized. It then recommends adding a layer of silicon oxide on top of the plasmonic layer. It shows that the protective silicon oxide layer slows down the oxidation process but also reduces the performance, describes that the protective silicon oxide layer is deposited by an e-beam process, which is very sophisticated and therefore expensive. [00046] The present disclosure overcomes the problem associated with metal oxidation by a very simple innovation of using metal alloy nanoparticlcs for the photonic process, which docs not lose its performance at all over time. By using nanoparticles of a metal alloy, for example, a metal alloy of three to four different materials (e.g., metals, semiconductors, and/or metalloids), the nanoparticles of the metal alloy may become non-oxidizing. Therefore, the present disclosure retains its enhanced performance for a long time and does not require an extra step of coating the nanoparticles of noble metals.

[00047] In one or more examples of the present disclosure, material composition includes metal alloy nanoparticles. These nanoparticles may include one or more metals, one or more semiconductors, and/or one or more metalloids. In one or more examples, the one or more metals may include transition metals (e.g., noble metals, such as gold, platinum, silver, copper, zinc, nickel etc.), etc. In one or more examples, the one or more semiconductors may include silicon, germanium, selenium, gallium, etc. In one or more examples, the one or more metalloids may include boron, silicon, germanium, etc.

[00048] In one or more examples, at least one of the metals may have excess electrons in the conduction band, while at least one of the alloying materials (e.g., alloying metal(s), alloying semiconductor(s), and/or alloying metalloid(s)) may have a relatively empty outermost valence band. The material with a relatively empty valence band may scavenge one or more electrons of the metal that has some energetic electrons in the conduction band. In one or more examples, the electron scavenger material in the alloy may render the alloy inoxidizable.

[00049] In one or more examples, the size of the plasmonic nanoparticles of the metal alloys may be approximately in the range of about 1/2 to about 1/15 of the wavelength of the incident light photons. In one or more examples, the wavelength of the incident light may range from about 320 nm to about 450 nm - including all values and sub-ranges thereof. In one or more examples, the size of the nanoparticles of the metal alloys may range from about 20 nm to about 225 nm - including all values and sub-ranges thereof.

[00050] In one or more examples, the photocatalyst may include TiCh, ZnO, SnCh, CdS, WO3, etc. In one or more examples, the size of the photocatalyst may range from about 20 nm to about 1000 nm - including all values and sub-ranges thereof. In one or more examples, the size of the photocatalyst may be in several microns. In one or more examples, greater efficiency may be achieved when the size of the photocatalyst may be less than several microns, e.g., ranging from about 20 nm to about 1000 nm - including all values and sub-ranges thereof.

[00051] In one or more examples, the mixture of photocatalyst and plasmonic nanoparticles may be applied to a surface to disinfect and detoxify indoor air. In one or more examples, nanoparticles of a photocatalyst, such as TiCh, ZnO, SnC>2, CdS, WO3, etc., may be mixed with a surfactant (e.g., an alcohol), a metallic salt, such as a metal chloride or nitrate etc., and/or nanoparticles of a metal alloy or metal oxide to create a mixture, such as a slurry.

[00052] In one or more examples, a surface, such as a substrate surface, may then be coated with the mixture and dried by heating the substrate. As will be discussed in more detail below, when the surface is exposed to UV-Vis light and a VOC, the VOC may be oxidized at a rate 45% - 60% faster than the conventional PECO technology. The present disclosure can be applied to many substrates, such as fibers, fabrics, filters, metals, metal foils, wallpapers, wall paints, etc., to disinfect and detoxify indoor air. An air purifier that uses the materials described herein to disinfect and detoxify indoor air has been disclosed herein.

[00053] In one or more examples, the disclosed modified catalyst (e.g., catalyst modified with metallic salt, another metal, plasmonic nanoparticles, etc.) creates positive ions that temporarily absorb the electrons freed from the photocatalyst, such as TiCh, ZnO, SnO2, CdS, WO3, etc., when incident photons are absorbed by the photocatalyst. This temporary absorption of free electrons facilitates the reactions in the present disclosure that destroy viruses and other organic contaminants/pollutants without the need to provide a metal mesh on the photocatalyst as required in certain conventional PECO technologies. Moreover, the chosen materials and sizes of the nanoparticles create specific photonic waves around them. These photonic waves interfere with the incident photons of light to create resonance, which increases the amount of hydroxyl free radicals by an order of magnitude over the conventional PECO technologies. The present disclosure, therefore, may be referred to as photonic technology.

[00054] In one or more examples, the present disclosure may accelerate the destruction process of organic contaminants by more than 50% over the conventional PECO technologies. Furthermore, as discussed above, the presence of the electron scavenger material in the metal alloy nanoparticles may render the alloy inoxidizable, thereby providing stable, enhanced performance over a long period of time. [00055] Accordingly, disclosed herein is a material composition for detoxifying a fluid includes a photocatalyst, and nanoparticlcs of a non-oxidizing metal alloy.

[00056] In one example, the non-oxidizing metal alloy comprises a metal and an electron scavenger. In one example, the nanoparticles are plasmonic nanoparticles. In another example, non-oxidizing metal alloy includes a transition metal. In another example, the non-oxidizing metal alloy comprises one or more of gold, platinum, silver, copper, zinc, and nickel. In a further example, the non-oxidizing metal alloy comprises a metal alloy of three to four different materials (e.g., metals, semiconductors, and/or metalloids)

[00057] In one example, the photocatalyst comprises one or more of TiCh, ZnO, SnCh, CdS, WO3. In one example, the photocatalyst has an average particle size ranging from about 20 nm to about 1000 nm. In another example, the nanoparticles of a non-oxidizing metal alloy have an average particle size ranging from about 30nm to about 70nm.

[00058] In one example, the material composition is configured to emit radiation at a frequency having a wavelength ranging from about 350nm to about 420nm. In another example, the material composition is configured to emit radiation at a frequency substantially equal to the frequency of surrounding radiation.

[00059] In one example, the material composition includes a surfactant. In one example, the surfactant is an alcohol.

[00060] Referring to FIG. 1, also disclosed is an article 100 for purifying a fluid. In one example, the article 100 includes a substrate 110 having a first surface 112 opposite a second surface 114, and a coating 120 over one of the first surface 112 and the second surface 114. The coating 120 includes a photocatalyst and plasmonic nanoparticles.

[00061] In one example, the substrate 110 includes a fibrous material, fabric, metal, cellulosic material, ceramic, or a paint. In one example, the photocatalyst comprises one or more of TiCF. ZnO, SnO2, CdS, WO3. In another example, the photocatalyst has an average particle size ranging from about 20 nm to about 1000 nm.

[00062] In one example, the plasmonic nanoparticles have an average particle size ranging from about 30nm to about 70nm. In another example, the plasmonic nanoparticles are non-oxidizable. In another example, the plasmonic nanoparticles comprise one or more metals, semiconductor, and metalloid. In another example, the plasmonic nanoparticles comprise one or more of gold, platinum, silver, copper, zinc, and nickel. In yet another example, the plasmonic nanoparticlcs comprise one or more of silicon, germanium, selenium, and gallium. In a further example, the plasmonic nanoparticles comprise one or more of boron, silicon, and germanium. In a further example, the plasmonic nanoparticles comprise a metal alloy of three to four different materials (e.g., metals, semiconductors, and/or metalloids).

[00063] Referring to FIG. 2, also disclosed is a system 200 for purifying a fluid. The system 200 includes a housing 240 having an inlet 242 and outlet 244, and defining a volume 246. The system 200 further includes an energy source, such as a light source 230, removably coupled to the housing 240. The light source 230 configured to emit electromagnetic radiation at a predetermined frequency. In one example, the light source 230 emits electromagnetic radiation in the ultraviolet frequency.

[00064] The system 200 further includes a substrate 210 positioned between the housing 240 and the light source 230. The substrate 210 includes plasmonic nanoparticles configured to emit radiation at the predetermined frequency. In one example, the radiation has a wavelength ranging from about 350nm to about 420nm.

[00065] The system 200 further includes a volume 246 defined by the housing 240 configured to receive the fluid. In one example, the fluid is air. In one example, the system 200 includes a fan 260 positioned adjacent the outlet 244 configured to draw the fluid from the inlet 242 through the volume 246 such that the fluid passes by the substrate 210. The system 200 may further include a transparent layer 220, such as a UV-A transparent glass, positioned between the substrate 210 and the light source 230.

[00066] Upon passing by the substrate 210, the fluid is positioned such that the electromagnetic radiation emitted from the light source 230 and the substrate 210 destroys pollutants in the fluid, thus purifying the fluid. The fluid may then be drawn to the outlet 244 of the housing 240 such that purified fluid is expelled from the housing 240.

[00067] In one example, the plasmonic nanoparticles have an average particle size ranging from about 1/2 to about 1/15 the size of the wavelength of the radiation emitted from the light source 230. In another example, the plasmonic nanoparticles have an average particle size ranging from about 30nm to about 70nm. In another example, the plasmonic nanoparticles are non-oxidizable. [00068] In one example, the plasmonic nanoparticles comprise one or more metals, semiconductor, and metalloid. In one example, the plasmonic nanoparticlcs comprise one or more of gold, platinum, silver, copper, zinc, and nickel. In another example, the plasmonic nanoparticles comprise one or more of silicon, germanium, selenium, and gallium. In yet another example, the plasmonic nanoparticles comprise one or more of boron, silicon, and germanium. In a further example, the plasmonic nanoparticles comprise a metal alloy of three to four different materials (e.g., metals, semiconductors, and/or metalloids).

[00069] In one example, the photocatalyst comprises one or more of TiCh, ZnO, SnCh, CdS, WO3. In one example, the photocatalyst has an average particle size ranging from about 20 nm to about 1000 nm.

[00070] Also disclosed is an air purifier. The air purifier includes a filter media coated with a coating, the coating including a photocatalyst and plasmonic nanoparticles.

[00071] In one example the plasmonic nanoparticles have an average particle size ranging from about 30nm to about 70nm. In one example, the plasmonic nanoparticles are non-oxidizable. In one example, the photocatalyst comprises one or more of TiCh, ZnO, SnO , CdS, WO3. In one example, the photocatalyst has an average particle size ranging from about 20 nm to about 1000 nm.

[00072] In one example, the plasmonic nanoparticles comprise one or more metals, semiconductor, and metalloid. In another example, the plasmonic nanoparticles comprise one or more of gold, platinum, silver, copper, zinc, and nickel. In another example, the plasmonic nanoparticles comprise one or more of silicon, germanium, selenium, and gallium. In yet another example, the plasmonic nanoparticles comprise one or more of boron, silicon, and germanium. In a further example, the plasmonic nanoparticles comprise a metal alloy of three to four different materials (e.g., metals, semiconductors, and/or metalloids).

[00073] Also disclosed is a method for manufacturing an article 100 for purifying a fluid. In one example, the method includes providing a substrate 110 having a first surface 112 opposite a second surface 1 14.

[00074] The method further includes mixing a photocatalyst with plasmonic nanoparticles to yield a coating composition. In one example, the method further includes mixing a surfactant with the photocatalyst and plasmonic nanoparticles. In one example, the surfactant is an alcohol. The method further includes applying the coating composition to one of the first surface and the second surface of the substrate, and drying the coating composition to yield a purifying coating 120.

[00075] In one example, the substrate 110 is a filter. In one example, the substrate 110 comprises a fibrous material, fabric, metal, cellulosic material, ceramic, or a paint. In one example, the photocatalyst comprises one or more of TiCh, ZnO, SnCh, CdS, WO3. In one example, the photocatalyst has an average particle size ranging from about 20 nm to about 1000 nm. In one example, the plasmonic nanoparticles have an average particle size ranging from about 30nm to about 70nm. In another example, the plasmonic nanoparticles are non-oxidizable.

[00076] In one example, the plasmonic nanoparticles comprise one or more metals, semiconductor, and metalloid. In another example, the plasmonic nanoparticles comprise one or more of gold, platinum, silver, copper, zinc, and nickel. In another example, the plasmonic nanoparticles comprise one or more of silicon, germanium, selenium, and gallium. In yet another example, the plasmonic nanoparticles comprise one or more of boron, silicon, and germanium. In a further example, the plasmonic nanoparticles comprise a metal alloy of three to four different materials (e.g., metals, semiconductors, and/or metalloids).

EXAMPLES

[00077] The following examples include experiments conducted to demonstrate the improvement of the present disclosure described herein for the destruction of organic chemicals including microorganisms, which are also organic in nature.

Experimental Set-Up

[00078] The schematic of FIG. 2 illustrates the experimental set up. Specifically, FIG. 2 shows a Photocatalytic oxidation reactor schematic with the reactor and with a sample loaded, along with a reactor chamber. Not pictured is a probe and meter coupled to the system to collect reaction rate data.

Exemplary Formulations

[00079] The following exemplary formulations were tested:

[00080] A: Control Basic PECO: nano-TiO2(99%)+Metal salt(l%) [00081] B: Control A Plasmonic Nanoparticles

[00082] The formulations were tested at least 20 times each. Each time the performance was consistent. The results of all the experiments with these formulations are presented in Figures 3 and 4. These Figures exhibit data for Samples of all the trials for these formulations. Reaction rate constants were calculated for each of these formulations and compared with the basic PECO formulation.

[00083] The calculated reaction rate constants for these formulations include:

[00084] Control PECO = 15.5xl0’³ min’¹, Plasmonic Photonic = 24.9xl0’³ min’¹.

[00085] Accordingly, the improvement of the Plasmonic Photonic formulation over the control from the experimental data collected was 60.7%, which is due to the addition of plasmonic nanoparticles.

[00086] Figure 3 exhibits the performance of the disclosed plasmonic photonic formulation as compared to the control PECO formulation A. The graph shows destruction of Toluene (a VOC) in the test chamber with time. The control line shows the performance with PECO control and the example line shows improved effectiveness of Plasmonic Photonic.

[00087] Figure 4 illustrates that the reaction rate constant remains stable within the experimental error limits for the formulations using the present disclosure. Each sample shows the Plasmonic Photonic coating going through multiple runs. The bars show that the performance is about the same within the error bars. In other words, it shows that the performance doesn’t go down with multiple runs.

[00088] While the present disclosure has been described with reference to several examples, which examples have been set forth in considerable detail for the purposes of making a complete disclosure of the disclosure, such examples are merely representative and are not intended to be limiting or represent an exhaustive enumeration of all aspects of the disclosure. The scope of the disclosure is to be determined from the claims appended hereto. Further, it will be apparent to those of skill in the art that numerous changes may be made in such details without departing from the spirit and the principles of the disclosure.

Claims

CLAIMS WHAT IS CLAIMED IS:

1. A material composition for purifying a fluid, comprising: a photocatalyst; and nanoparticles of a non-oxidizing metal alloy.

2. The material composition according to claim 1, wherein the non-oxidizing metal alloy comprises a metal and an electron scavenger.

3. The material composition according to claim 1, wherein the non-oxidizing metal alloy comprises a transition metal.

4. The material composition according to claim 1, wherein the non-oxidizing metal alloy comprises one or more of gold, platinum, silver, copper, zinc, and nickel.

5. The material composition according to claim 1, wherein the nanoparticles of a nonoxidizing metal alloy are plasmonic nanoparticles.

6. The material composition according to claim 1, wherein the photocatalyst comprises one or more of TiCh, ZnO, SnOz, CdS, WO3.

7. The material composition according to claim 1, wherein the photocatalyst has an average particle size ranging from about 20 nm to about 1000 nm.

8. The material composition according to claim 1, wherein the nanoparticles of a nonoxidizing metal alloy have an average particle size ranging from about 30nm to about 70nm.

9. The material composition according to claim 1 configured to emit radiation at a frequency having a wavelength ranging from about 350nm to about 420nm.

10. The material composition according to claim 1, further comprising a surfactant.

11. The material composition according to claim 10, wherein the surfactant is an alcohol.

12. An article for purifying a fluid, the article comprising: a substrate having a first surface opposite a second surface; and a coating over one of the first surface and the second surface, the coating comprising: a photocatalyst; and plasmonic nanoparticles.

13. The article according to claim 12, wherein the substrate comprises a fibrous material, fabric, metal, cellulosic material, ceramic, or a paint.

14. The article according to claim 12, wherein the photocatalyst comprises one or more of TiO₂, ZnO, SnO₂, CdS, WO₃.

15. The article according to claim 12, wherein the photocatalyst has an average particle size ranging from about 20 nm to about 1000 nm.

16. The article according to claim 12, wherein the plasmonic nanoparticles have an average particle size ranging from about 30nm to about 70nm.

17. The article according to claim 12, wherein the plasmonic nanoparticles are non-oxidizable.

18. The article according to claim 12, wherein the plasmonic nanoparticles comprise one or more metals, semiconductor, and metalloid.

19. The article according to claim 12, wherein the plasmonic nanoparticles comprise one or more of gold, platinum, silver, copper, zinc, and nickel.

20. The article according to claim 12, wherein the plasmonic nanoparticles comprise one or more of silicon, germanium, selenium, and gallium.

21. The article according to claim 12, wherein the plasmonic nanoparticles comprise one or more of boron, silicon, and germanium.

22. A system for purifying a fluid, the system comprising: a housing defining a volume, the volume configured to receive the fluid; a light source removably coupled to the housing, the light source configured to emit radiation at a predetermined frequency; and a substrate positioned between the housing and the light source, the substrate comprising plasmonic nanoparticles configured to emit radiation at the predetermined frequency.

23. The system according to claim 22, further comprising a fan positioned adjacent an outlet of the housing, the fan configured to draw the fluid through the volume such that it passes by the substrate.

24. The system according to claim 22, wherein the fluid is air.

25. The system according to claim 22, wherein the radiation has a wavelength ranging from about 350nm to about 420nm.

26. The system according to claim 22, wherein the photocatalyst comprises one or more of TiO₂, ZnO, SnO₂, CdS, WO₃.

27. The system according to claim 22, wherein the photocatalyst has an average particle size ranging from about 20 nm to about 1000 nm.

28. The system according to claim 22, wherein the plasmonic nanoparticles have an average particle size ranging from about 1/2 to about 1/15 the size of the wavelength of the radiation emitted from the light source.

29. The system according to claim 22, wherein the plasmonic nanoparticles have an average particle size ranging from about 30nm to about 70nm.

30. The system according to claim 22, wherein the plasmonic nanoparticles are non-oxidizable.

31. The system according to claim 22, wherein the plasmonic nanoparticles comprise one or more metal, semiconductor, and metalloid.

32. The system according to claim 22, wherein the plasmonic nanoparticles comprise one or more of gold, platinum, silver, copper, zinc, and nickel.

33. The system according to claim 22, wherein the plasmonic nanoparticles comprise one or more of silicon, germanium, selenium, and gallium.

34. The system according to claim 22, wherein the plasmonic nanoparticles comprise one or more of boron, silicon, and germanium.

35. An air purifier comprising: a filter media coated with a coating, the coating comprising: a photocatalyst; and plasmonic nanoparticles.

36. The air purifier according to claim 35, wherein the photocatalyst comprises one or more of TiO₂, ZnO, SnO₂, CdS, WO₃

37. The air purifier according to claim 35, wherein the photocatalyst has an average particle size ranging from about 20 nm to about 1000 nm.

38. The air purifier according to claim 35, wherein the plasmonic nanoparticlcs have an average particle size ranging from about 30nm to about 70nm.

39. The air purifier according to claim 35, wherein the plasmonic nanoparticles are non- oxidizable.

40. The air purifier according to claim 35, wherein the plasmonic nanoparticles comprise one or more metal, semiconductor, and metalloid.

41. The air purifier according to claim 35, wherein the plasmonic nanoparticles comprise one or more of gold, platinum, silver, copper, zinc, and nickel.

42. The air purifier according to claim 35, wherein the plasmonic nanoparticles comprise one or more of silicon, germanium, selenium, and gallium.

43. The air purifier according to claim 35, wherein the plasmonic nanoparticles comprise one or more of boron, silicon, and germanium.

44. A method for manufacturing an article for purifying a fluid, the method comprising: providing a substrate having a first surface opposite a second surface; mixing a photocatalyst with plasmonic nanoparticles to yield a coating composition; applying the coating composition to one of the first surface and the second surface of the substrate; and drying the coating composition to yield a purifying coating.

45. The method according to claim 44, wherein the substrate is a filter.

46. The method according to claim 44, wherein the substrate comprises a fibrous material, fabric, metal, cellulosic material, ceramic, or a paint.

47. The method according to claim 44, wherein the photocatalyst comprises one or more of TiO₂, ZnO, SnO₂, CdS, WO₃.

48. The method according to claim 44, wherein the photocatalyst has an average particle size ranging from about 20 nm to about 1000 nm.

49. The method according to claim 44, wherein the plasmonic nanoparticles have an average particle size ranging from about 30nm to about 70nm.

50. The method according to claim 44, wherein the plasmonic nanoparticles are non- oxidizable.

51. The method according to claim 44, wherein the plasmonic nanoparticles comprise one or more metal, semiconductor, and metalloid.

52. The method according to claim 44, wherein the plasmonic nanoparticles comprise one or more of gold, platinum, silver, copper, zinc, and nickel.

53. The method according to claim 44, wherein the plasmonic nanoparticles comprise one or more of silicon, germanium, selenium, and gallium.

54. The method according to claim 44, wherein the plasmonic nanoparticles comprise one or more of boron, silicon, and germanium.

55. The method according to claim 44, further comprising mixing a surfactant with the photocatalyst and plasmonic nanoparticles.

56. The method according to claim 44, wherein the surfactant is an alcohol.