Activated carbon modified by atomic layer deposition and methods thereof

Abstract

To provide modified activated adsorbent materials modified by atomic layer deposition methods, and methods, and systems including the same.SOLUTION: The present description provides structures, atomic layer deposition methods for preparing the structures, and an apparatus preparing the structures. The described structures provide unexpected advantages as compared to currently available materials.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] (Cross - Reference to Related Applications) This application claims the benefit of U.S. Patent Application No. 63 / 035,224, filed on June 5, 2020, which is hereby incorporated by reference in its entirety.

[0002] The present disclosure relates, in various aspects and embodiments, to modified, e.g., atomically deposited, activated sorbent materials, and methods, and systems including them.

Background Art

[0003] In catalyst - driven processes, the reaction rate is often limited by the number of available active sites on the catalyst substrate. As a result, maximizing surface area is an important design aspect of many heterogeneous catalyst systems. One method frequently used to achieve a high surface area is to disperse a catalytically active material (e.g., TiO2, SiO2, or Al2O3) onto a high - surface - area support material such as activated carbon. For example, TiO2 has a wide range of industrial - related applications, including, to name a few, photocatalysts, catalysts for NOx reduction via selective catalytic reduction (SCR) for stationary power applications, various active metals, pigments and coatings, ceramics, and catalyst supports for various consumer products.

[0004] One of the commonly employed techniques for dispersing a catalytically active material onto a support material is the solution dropwise impregnation method, by which initially the active material is dissolved in a solution, often as a nitrate (e.g., Ce(NO3)3), and then added to the porous support, where capillary action draws the solution into the porous structure. Once the pores of the support are filled with the solution, the saturated support is dried and then calcined to drive off volatile species, depositing the active metal onto the walls of the support. This technique is relatively effective at dispersing the active material onto the support structure, but this technique presents several notable drawbacks. First, the particle size is not well controlled, resulting in a portion of the active material that cannot be utilized. In addition, there is often poor contact between the deposited active material and the support material, which generally leads to crystallization and aggregation of the active phase, resulting in further loss of surface area and active material utilization. Similarly, upon heating the active metal particles, sintering produces larger particles, reducing the atomic efficiency. Furthermore, only a portion of the support surface is covered with the active material by this technique.

[0005] An alternative technique that has recently been explored to disperse metal particles onto an oxide support is atomic layer deposition (ALD). Compared to the conventional loading of a support with an active metal material, the advantage of using ALD is that it enables the deposition of metals or metal oxides in a highly dispersed manner and thus improves the atomic efficiency and surface area of the catalytically active metal material. During ALD, the active metal material is introduced onto the support as a vapor. To provide sufficient vapor pressure, the active metal material is typically prepared in a metalorganic form. When the support material is exposed to the metalorganic vapor, the surface of the support is coated with the metalorganic precursor until saturation. Ideally, the conditions under which the metalorganic precursor is adsorbed onto the surface result in the first layer being partially oxidized and strongly adsorbed onto the surface. After exposure to the metalorganic precursor, the support is purged with an inert species or exposed to vacuum for a certain period to remove the adsorbed multilayer species. At this point, the support coated with the active metal is exposed to an oxidizing agent such as ozone, water, or calcined in air to completely oxidize the adsorbed metalorganic species. The oxidation following this stepwise sequence of precursor introduction is referred to as a single ALD cycle. Assuming that each cycle consists of only the adsorption of a single monolayer of the precursor material, the process is essentially self-limiting and results in no more than a single atomic layer per cycle.

[0006] ALD is commonly used in semiconductor device manufacturing and has recently been explored for the synthesis of catalytically active materials. In both of these applications, ALD is carried out on a support material or substrate material having surface - bound functional groups (e.g., oxygen - containing functional groups), and oxygen atoms initiate the ALD growth mechanism by partially oxidizing the adsorbed organometallic species. Conventional methods use a carrier gas such as helium to deliver the precursor gas to the substrate, which was developed by the semiconductor industry for deposition on relatively flat surfaces rather than on highly porous surfaces that are used, for example, as supports for heterogeneous catalysts. Substrates used in conventional methods for semiconductor manufacturing generally have a flat surface and thus less surface area, so the exposure time of the substrate to the precursor gas is very short, enabling rapid cycles, but less active metal material is deposited per cycle, often requiring many cycles. To achieve a similar loading, the number of cycles required to modify the surface of a porous (i.e., relatively high surface area) material is much less than that of a planar semiconductor material, but the diffusion of precursors and oxidants through the porous material limits the rate at which the cycles can be carried out.

[0007] Due to the slow diffusion of the precursor gas inside and outside the pores of the porous substrate material, the use of a carrier gas as in conventional methods is not practical and leads to increased costs because the precursor gas is blown through the system and not recovered. Thus, there is a need in the art for improvements in catalytically active porous materials and methods for their manufacture. SUMMARY OF THE INVENTION

[0008] A porous structure and method of making the same are described herein. Surprisingly and unexpectedly, it has been discovered that a porous material, such as an activated adsorption material like activated carbon, can function as a substrate for ALD.

[0009] Accordingly, in one aspect, the present specification provides a structure comprising an active adsorption material, such as a porous active adsorption material, and metal species deposited thereon. In certain aspects, the present specification also provides a structure comprising a substrate including an active adsorption material and metal species deposited thereon.

[0010] In additional aspects, the present specification provides a method for preparing a structure by a process comprising: (a) providing, within a reactor, an active adsorption material, such as a porous active adsorption material (e.g., activated carbon); and (b) performing or carrying out at least one atomic layer deposition cycle to deposit metal species, such as metal oxides, wherein the at least one atomic layer deposition cycle comprises a cycle including: (i) introducing a first precursor gas into the reactor to provide a metal species precursor; and (ii) introducing a second precursor gas into the reactor to provide a structure. In any aspect or embodiment, step (b) is repeated from 2 to about 10 times.

[0011] In additional aspects, the present specification provides a structure prepared by atomic layer deposition (ALD) by a process comprising: (a) providing, within a reactor, an active adsorption material, such as a porous active adsorption material (e.g., activated carbon); and (b) performing at least one atomic layer deposition (ALD) cycle to deposit metal species, such as metal oxides, wherein the at least one atomic layer deposition cycle comprises a cycle including: (i) introducing a first precursor gas into the reactor to provide a metal species precursor; and (ii) introducing a second precursor gas into the reactor to provide a structure.

[0012] In any aspect or embodiment described herein, a structure prepared by atomic layer deposition (ALD) is a porous metal-coated structure.

[0013] In any aspect or embodiment described herein, the active adsorbent material is a porous active adsorbent material. In any aspect or embodiment described herein, the porous active adsorbent material includes activated carbon, such as porous activated carbon. In any aspect or embodiment described herein, the activated carbon includes activated carbon powder, granules, pellets, monoliths, or honeycomb forms.

[0014] In any of the aspects or embodiments described herein, the metal species includes at least one metal. The metal species may be derived from a metal species precursor having at least one metal and at least one ligand, which may then be synthetically modified (e.g., oxidized or reduced) to provide the metal species.

[0015] The foregoing general description of utility is provided by way of example only and is not intended to limit the scope of the present disclosure or the appended claims. Additional objects and advantages associated with the compositions, methods, and processes of the present invention will be understood by those skilled in the art from the perspective of the claims, description, and examples of the present invention. For example, the various aspects and embodiments of the present invention may be utilized in numerous combinations, all of which are explicitly contemplated herein. These additional advantages, objects, and embodiments are explicitly included within the scope of the present invention. Publications and other samples used to explain the background of the present invention and to provide additional details regarding implementation in specific cases are incorporated by reference.

[0016] The accompanying drawings, which are incorporated herein and form a part hereof, illustrate several embodiments of the present invention and, together with the description, serve to explain the principles of the present invention. The drawings are for the purpose of illustrating only one embodiment of the present invention and are not to be construed as limiting the present invention. In conjunction with the accompanying drawings showing exemplary embodiments of the invention, further objects, features, and advantages of the invention will become apparent from the following mode for carrying out the invention.

Brief Description of the Drawings

[0017]

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Mode for Carrying Out the Invention

[0018] Here, the present disclosure will be described more fully below, but not all embodiments of the present disclosure are shown. Although the present disclosure has been described with reference to exemplary embodiments, those skilled in the art will understand that various changes may be made without departing from the scope of the present disclosure, and its elements may be replaced with equivalents. In addition, many modifications may be made to adapt a particular structure or material to the teachings of the present disclosure without departing from the essential scope of the present disclosure.

[0019] The drawings attached to this application are for illustrative purposes only. They are not intended to limit the embodiments of this application. In addition, the drawings are not drawn to scale. Common elements between figures may sometimes be designated by the same numerals.

[0020] When a range of values is provided, it is understood that each value that lies within the range and between the upper and lower limits of other described ranges, or values that fall within the described range, is encompassed by the present invention. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges, which are also encompassed within the present invention and become any specifically excluded boundary values within the described range. When the described range includes one or both of the boundary values, ranges excluding either, both of the included boundary values are also included in the present invention.

[0021] The following terms are used to describe the present invention. When a term is not specifically defined herein, the term is given the meaning recognized in the art by those of ordinary skill in the art as appropriate in the context of the use of the term in the description of the present invention.

[0022] As used in this specification and the appended claims, the articles "a" and "an" are used herein to refer to one or more than one (i.e., at least one) of the grammatical objects of the article, unless the context clearly dictates otherwise. By way of example, "an element" means one element or more than one element.

[0023] As used herein in the specification and claims, the phrase "and / or" should be understood to mean "any one or both" of the elements so conjoined. That is, in some instances the elements may exist in combination, and in other instances they may exist separately. Multiple elements listed using "and / or" should be construed in the same fashion. That is, "one or more" of the elements are so conjoined. Other elements other than those specifically identified by the "and / or" clause may optionally exist, regardless of their relevance to the specifically identified elements. Therefore, by way of non-limiting example, when used in conjunction with open-ended language such as "comprising", a reference to "A and / or B" may, in one embodiment, refer to only A (optionally including elements other than B), in another embodiment, may refer to only B (optionally including elements other than A), and in yet another embodiment, may refer to both A and B (optionally including other elements), and so on.

[0024] As used herein in the specification and claims, "or" should be understood to have the same meaning as "and / or" as defined above. For example, when separating items in a list, "or" or "and / or" shall be construed as inclusive. That is, it includes one or more of the many elements, or at least one of the list of elements, but also includes two or more, and optionally additional items not listed. Only terms that clearly indicate the contrary, such as "only one of", or "exactly one of", or when used in the claims "consisting of", refer to the inclusion of exactly one element of the many elements, or list of elements. Generally when used herein, the term "or" shall be construed to indicate an exclusive alternative (i.e., "one or the other but not both") only when preceded by exclusive terms such as "either", "one of", "only one of", or "exactly one of".

[0025] Not only in the claims, but also in the above specification, all transitional phrases such as "comprising", "including", "carrying", "having", "containing", "involving", "holding", "composed of", and the like, are to be understood as open-ended, i.e., they include but are not limited to. Only the transitional phrases "consisting of" and "consisting essentially of" are to be regarded as closed, or semi-closed transitional phrases, respectively, as described in Section 2111.03 of the 10th Edition of the United States Patent Office Manual of Patent Examining Procedures.

[0026] As used herein in the specification and claims, with respect to a list of one or more elements, the phrase "at least one" should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of every element specifically listed within the list of elements, nor excluding any combination of elements in the list of elements. This definition also allows that, in addition to the elements specifically identified within the list of elements to which the phrase "at least one" refers, optionally such elements may exist regardless of the presence or absence of their relevance to the specifically identified elements. Therefore, by way of non-limiting example, "at least one of A and B" (or equivalently, "at least one of A or B", or equivalently, "at least one of A and / or B") can refer, in one embodiment, to at least one, optionally including two or more A's, where B is absent (and optionally including elements other than B), in another embodiment, to at least one, optionally including two or more B's, where A is absent (and optionally including elements other than A), and in yet another embodiment, to at least one, optionally including two or more A's, and at least one, optionally including two or more B's (and optionally including other elements), etc. It should also be understood that, unless expressly indicated to the contrary, in any method claimed herein that includes two or more steps or operations, the order of the steps or operations of the method is not necessarily limited to the order of the steps or operations of the method as recited.

[0027] As used herein, the terms "fluid", "gas" or "gaseous", and "vapor" or "vaporous" are used in their ordinary sense and are intended to be interchangeable unless the context indicates otherwise.

[0028] In an ALD process where a precursor gas chemisorbs onto the surface of a substrate, the presence of functional groups (e.g., oxide species) on the surface of the substrate that have the ability to react with the precursor gas and replace the ligand of the precursor gas is required. Typically, in order to provide a uniform monolayer coating of the substrate, it is desirable to have a sufficient density of adsorption sites (the number of surface functional groups per unit area) on the surface of the substrate. For example, silicon wafers commonly used in semiconductor manufacturing have silanol groups that uniformly cover the surface, such that when ALD is used to apply a metal oxide coating, saturation of the surface of the silicon wafer substrate by the ALD layer is expected due to the large number of surface silanol groups.

[0029] In the case of porous carbon-based substrates such as activated carbon, the surface is non-uniform, and the site density of these functional groups is non-uniform and is expected to be smaller than the adsorption site density of commonly used substrates such as silicon wafers. As a result, precursor chemisorption and partial oxidation for ALD growth are unexpected. Therefore, in order to achieve ALD on many carbon-based materials, the surface of the carbon-based materials must first be pretreated to modify its interfacial chemistry. For example, it has been demonstrated that carbon nanotubes (CNTs) can be coated using ALD, but carbon materials require surface modification prior to the ALD process. Surface functionalization of CNTs is often employed to increase steric hindrance between adjacent CNTs, facilitate exfoliation, and improve solubility. Surface functionalization also potentially provides sites for ALD. Conventional examples of CNT surface modification include chemicals for surface oxidation, annealing using plasma, or non-covalent groups (such as surfactants, polymers, or DNA). Another conventional method of surface modification involves depositing a metal seed on the surface by physical vapor deposition. Yet another conventional method used for CNT surface modification is treatment with diazonium salts to add aryl or aliphatic groups to its surface. Diazonium salts have also been used to functionalize porous carbon materials, such as activated carbon. U.S. Patent No. 7,698,191 teaches the use of diazonium salt chemistry reactions with carbon materials to provide organic functional groups. Surface-bound organic functional groups enable metal deposition on carbon materials via the ALD process. The use of diazonium salts is an effective means of controlling the scope and nature of surface functionality. However, the functionality that can be added by this technique is mainly limited to organic species. The addition of functional groups such as diazonium salt treatment is beneficial for the exfoliation of CNTs and may also provide functionality for ALD, but the additional steric hindrance resulting from the addition of functional groups on porous substrates may lead to a loss of pore volume even before ALD.This additional processing step not only introduces additional complexity and a decrease in atomic efficiency in the preparation of the substrate, but also brings additional process safety risks posed by many diazonium salts. Therefore, it has surprisingly and unexpectedly been discovered that it is possible to modify a heterogeneous porous active adsorbent material, such as activated carbon, with metal oxides using an ALD method without using a surface pretreatment to modify the interfacial chemistry or add surface functional groups. Thus, in either aspect or embodiment, the present specification provides a process and method that exclude any additional steps of treating a substrate comprising an active adsorbent material to modify the interfacial chemistry or add surface functional groups, apart from activation.

[0030] Surprisingly and unexpectedly, structures are described herein that demonstrate that active adsorbent materials, such as activated carbon, can function as substrates for ALD. The ALD method in which a precursor gas chemisorbs onto the surface of the substrate requires the presence of functional groups (i.e., oxide species) on the surface of the substrate that have the ability to react with the precursor gas and replace the ligands of the precursor gas. Typically, it is desirable to have a sufficient density of adsorption sites on the surface of the substrate to provide a uniform monolayer coating of the substrate. However, in the case of an adsorbent material such as activated carbon, the adsorption site density may be lower than that of commonly used substrates such as silicon wafers used in ALD methods in the semiconductor industry. Since the adsorption site density may be lower for activated carbon, the substrate surface with metal species may not be saturated and the layer may not be uniform. Therefore, it has surprisingly and unexpectedly been discovered that it is possible to modify an adsorbent material such as activated carbon with metal species such as metal oxides using an ALD method.

[0031] Accordingly, in any aspect or embodiment, the present specification provides a structure comprising an active adsorbent material, such as a porous active adsorbent material, and metal species deposited thereon. In certain aspects or embodiments, the present specification also provides a structure comprising a substrate comprising an active adsorbent material, such as a porous active adsorbent material, and metal species deposited thereon.

[0032] As used herein, unless the context indicates otherwise, the term "substrate (or material) comprising (or including) an active adsorbent material" means a substrate or material comprising from 1 to 100 wt% (e.g., at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or 100 wt%, including all ranges and sub-ranges therebetween) of an active adsorbent material, such as a porous active adsorbent material as described herein. For example, if the substrate or material comprises less than 100 wt% of the active adsorbent material, the balance up to 100 wt% can comprise one or more additives known in the art, by way of non-limiting example, binders, processing aids, or the like.

[0033] When the metal species comprises titanium oxide, the structure surprisingly and unexpectedly demonstrates excellent catalytic activity compared to commonly used titanium oxide nanoparticles (e.g., those commercially available as P25 TiO2 (Evonik)).

[0034] In any of the aspects or embodiments described herein, the substrate of this structure includes an active adsorption material. Examples of the active adsorption material include activated carbon, charcoal, zeolite, clay, porous polymer, foam, porous alumina, porous silica, molecular sieve, kaolin, titania, ceria, or combinations thereof. In any of the aspects or embodiments described herein, the active adsorption material is activated carbon. The active adsorption material can be derived from an active adsorption material precursor. As non-limiting examples, the active adsorption material precursor can be wood, wood dust, wood flour, cotton linter, peat, coal, coconut, lignite, carbohydrate, petroleum pitch, petroleum coke, coal tar pitch, fruit pit, fruit stone, nut shell, nut pit, sawdust, palm, vegetables (such as rice husk or straw), synthetic polymer, natural polymer, lignocellulosic material, or combinations thereof. Further, the active adsorption material may be produced using various processes including, but not limited to, chemical activation, thermal activation, or combinations thereof.

[0035] In any of the aspects or embodiments described herein, the active adsorbent material comprises activated carbon powder. The activated carbon is processed to be highly porous (i.e., having a large number of pores per unit volume), which imparts a high surface area. In any of the aspects or embodiments described herein, the surface of the active adsorbent material of the substrate is not modified, for example, prior to the deposition of metal species using ALD. As used herein, "modification" of the surface of the active adsorbent material excludes the activation process. The active adsorbent material can be prepared using an activation process. In any of the aspects or embodiments described herein, the active adsorbent material is activated carbon. Natural carbon (non-activated carbon) can be activated using an activator comprising at least one of phosphoric acid, sulfuric acid, boric acid, nitric acid, oxygenated acid, steam, air, peroxide, alkali hydroxide, metal chloride, ammonia, carbon dioxide, or combinations thereof. The activation conditions, including temperature and pressure, are within the skill of those in the art. As used herein, "modification" includes reaction with a diazonium salt to add an aryl or aliphatic group linker to a surface substituted with a functional group. In any of the aspects or embodiments described herein, the surface of the active adsorbent material is not modified by reaction with a diazonium salt to add a functionalized aryl or aliphatic group linker group bound to the surface.

[0036] In any of the aspects or embodiments described herein, activated carbon can be derived from an activated carbon precursor. Activated carbon may be produced from a variety of materials, although most commercially available activated carbon is made from peat, coal, lignite, wood, and coconut shells. Based on the raw materials, the carbon can have different pore sizes, ash contents, surface orders, and / or impurity profiles. Coconut shell-based carbon mostly has microporous pore sizes, while wood-based chemically activated carbon mostly has mesoporous or macroporous pore sizes. In a preferred embodiment, the activated carbon includes activated carbon powder. As non-limiting examples, the activated carbon precursor may be wood, wood dust, wood flour, cotton linter, peat, coal, coconut, lignite, carbohydrate, petroleum pitch, petroleum coke, coal tar pitch, fruit pit, fruit stone, nut shell, nut pit, sawdust, palm, vegetables (such as rice husks or straw), synthetic polymers, natural polymers, lignocellulosic materials, or combinations thereof. Further, the activated carbon may be produced using various processes including, but not limited to, chemical activation, thermal activation, or combinations thereof.

[0037] In any of the aspects or embodiments described herein, the activated carbon precursor is wood. The activated carbon precursor can be activated by heating the activated carbon precursor and treating it with an added oxidizing agent (such as an externally added activating agent, i.e., oxidation), such as carbon dioxide, oxygen, acid, or superheated steam. An exemplary activated carbon is Nuchar® (Ingevity South Carolina, LLC, South Carolina, USA), a chemically activated carbon derived from wood and activated with phosphoric acid.

[0038] Generally, the larger the surface area of activated carbon, the greater its adsorption capacity. For example, the available surface area of activated carbon depends on its pore volume. Since the surface area per unit volume decreases as the individual pore size increases, generally, a large surface area is maximized by maximizing the number of pores of a very small size and / or minimizing the number of pores of a very large size. Pore size is defined herein as micropores (pore width < 2.0 nm), mesopores (pore width = 2.0 - 50 nm), and macropores (pore width > 50 nm and nominally 50 nm - 100 micrometers). Mesopores may further be divided between small mesopores (pore width = 2.0 - 5 nm) and large mesopores (pore width = 5 - 50 nm).

[0039] The Brunauer-Emmett-Teller (B.E.T.) surface can characterize the specific surface area of a material. The activated adsorption material (e.g., activated carbon) preferably has a nitrogen B.E.T. surface area of about 600 to about 2300, about 800 to about 1800, or about 1000 to about 1600 m2 / gram. The surface area was measured by nitrogen physical adsorption using the Brunauer-Emmett-Teller (BET) method in accordance with ISO 9277:2010 on a Micromeritics ASAP 2420 (Norcross, Georgia, USA). The pore volume was determined by nitrogen adsorption porosimetry using a Micromeritics ASAP 2420 (Norcross, Georgia, USA). Briefly, the example / sample was dried overnight in an oven preset to 105 - 110 °C. The sample was removed and placed in a closed system until the temperature equilibrated with the laboratory. The sample was inserted into the sample tube of the instrument and placed on the Micromeritics ASAP 2420 instrument. The sample was degassed in situ before the start of the test. The degassing of the sample was carried out at 250 °C and a vacuum of 2 μmHg. The pore volume was calculated from the P / Po isotherm using the SAIEUS program. The non-ideal coefficient was 0.0000620. The density conversion coefficient was 0.0015468. The rigid sphere diameter was 3.860 Å. The molecular cross-sectional area was 0.162 nm2. The target relative pressure (in mmHg) for the isotherm was 0.002, 0.005, 0.01, 0.0125, 0.0250, 0.050, 0.075, 0.1, 0.1125, 0.125, 0.150, 0.175, 0.20, 0.25, 0.30, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, and 0.95. At low pressure, the instrument was set to the "low pressure incremental dose mode", which instructs the instrument to record data based on an incremental dose of an amount of 20,000 cm3 / g of STP. The actual points were recorded within an absolute pressure tolerance or relative pressure tolerance that was more stringent of either 5 mmHg or 5% each. The time between consecutive pressure readings during equilibration was 20 seconds. When the ΔP between readings was <0.001%, data was taken and P was set to the next set point.The minimum delay time between data recordings was 600 seconds. The nitrogen adsorption isotherm data was analyzed by the SAIEUS program. The "Max" field in the pore size range was changed to 500. In the L-curve chart, the lambda value was set by scrolling the bar to find the point of contact on the curve. The mathematical model that processes the isotherm data accumulated by Micromeritics equipment to determine the pore size distribution is described as non-local density functional theory (NLDFT). This model appears to minimize the associated error (equalize with small pores) in the low pressure range, as described in J. Phys. Chem., 2009, 113, 19382-19385 (by J. Jagiello and J. P. Olivier).

[0040] As previously discussed, in any of the aspects or embodiments described herein, in addition to activation, the activated adsorbent material is not further modified. The modification of the substrate surface can introduce additional surface functional groups such that the number of functional groups covalently bonded to the adsorbent material and having the ability to bind metal species increases. Alternatively, the modification of the substrate surface can include coating with a material (e.g., surfactant) having the ability to bind metal species. Thus, the modification of the substrate surface can increase the density of adsorption sites on the surface. The surface of the activated adsorbent material that has not been further modified after activation can have a lower density of adsorption sites than the surface of the activated adsorbent material that has undergone further surface modification after activation. The ratio of heteroatoms such as oxygen, nitrogen, and phosphorus to carbon can be proportional to the density of adsorption sites on the surface of the activated adsorbent material.

[0041] One way to measure the density of adsorption sites is surface elemental analysis. Surface analysis techniques can provide information about the chemical composition of the material surface depending on the analytical method used. The density of elements (e.g., O, N, and P) can be measured using, for example, beam titration or Auger electron spectroscopy (AE).

[0042] Another way to measure the adsorption site density is bulk elemental analysis within a specified sampling depth from the surface. X-ray photoelectron spectroscopy (XPS) can be used at sampling depths of about 5 nm or less, or about 4 nm or less, or about 3 nm or less, or about 2 nm or less, or about 1 nm or less. XPS is performed to obtain the concentrations of carbon, chlorine, fluorine, sodium, nitrogen, oxygen, phosphorus, titanium, and palladium by sprinkling the sample powder onto double-sided adhesive tape and removing the excess before introducing it into the vacuum chamber. Data was acquired from an analyzed area having a diameter of approximately 1 mm using a monochromatic Al Kα X-ray source and a takeoff angle of 65°. A low-energy resolution survey scan was obtained from each sample to determine which elements were present. The atomic concentrations of these elements and their local chemistry were determined from more high-energy resolution multiple scans.

[0043] In any of the aspects or embodiments described herein, the bulk oxygen-to-carbon ratio at a sampling depth of about 5 nm or less is about 0.25 or less, about 0.20 or less, about 0.15 or less, about 0.10 or less, about 0.09 or less, about 0.08 or less, about 0.07 or less, about 0.06 or less, about 0.05 or less, about 0.01 to about 0.25, about 0.01 to about 0.25, about 0.01 to about 0.20, about 0.01 to about 0.15, or about 0.01 to about 0.10, including all overlapping ranges, inclusive ranges, and values therebetween.

[0044] In any of the aspects or embodiments described herein, the bulk phosphorus-to-carbon ratio at a sampling depth of about 5 nm or less is about 0.10, about 0.09, about 0.08, about 0.07, about 0.06, about 0.05 or less, including all overlapping ranges, inclusive ranges, and values therebetween.

[0045] In any of the aspects or embodiments described herein, the bulk nitrogen-to-carbon ratio at a sampling depth of about 5 nm or less is about 0.10, about 0.09, about 0.08, about 0.07, about 0.06, or about 0.05 or less, including all overlapping ranges, inclusive ranges, and values therebetween.

[0046] As used herein, "surface oxygen-to-carbon ratio" refers to the ratio of surface carbon bonded to oxygen to the total number of surface carbons. The total number of surface carbons includes unbonded surface carbons, carbon bonded to oxygen, and carbon bonded to other elements or groups. In any of the aspects or embodiments described herein, the surface oxygen-to-carbon ratio is less than about 1.0, less than about 0.95, less than about 0.90, less than about 0.85, less than about 0.80, less than about 0.75, less than about 0.70, less than about 0.65, less than about 0.60, less than about 0.55, less than about 0.50, less than about 0.45, less than about 0.40, less than about 0.35, less than about 0.30, less than about 0.25, less than about 0.20, less than about 0.15, less than about 0.10, from about 0.01 to less than about 1.0, from about 0.10 to less than about 1.0, from about 0.05 to less than about 1.0, from about 0.01 to less than about 0.95, from about 0.01 to less than about 0.90, from about 0.01 to less than about 0.85, from about 0.01 to less than about 0.80, from about 0.01 to less than about 0.75, from about 0.01 to less than about 0.70, from about 0.01 to less than about 0.65, from about 0.01 to less than about 0.60, from about 0.01 to less than about 0.55, from about 0.01 to less than about 0.50, from about 0.01 to less than about 0.45, from about 0.01 to less than about 0.40, from about 0.01 to less than about 0.35, from about 0.01 to less than about 0.30, from about 0.01 to less than about 0.25, from about 0.01 to less than about 0.20, including all overlapping ranges, inclusive ranges, and values therebetween.

[0047] As used herein, "surface phosphorus to carbon ratio" refers to the ratio of surface carbon bound to phosphorus to the total number of surface carbons. The total number of surface carbons includes unbound surface carbons, carbons bound to phosphorus, and carbons bound to other elements or groups. It is understood that surface phosphorus can be bound to surface carbon via a heteroatom linker (e.g., oxygen). Surface phosphorus can exist in an oxidized or non-oxidized state. In any of the aspects or embodiments described herein, the surface phosphorus to carbon ratio is less than or equal to about 0.33, about 0.30, about 0.25, about 0.20, about 0.15, about 0.10, including all overlapping ranges, encompassing ranges, and values therebetween.

[0048] As used herein, "surface nitrogen to carbon ratio" refers to the ratio of surface carbon bound to nitrogen to the total number of surface carbons. The total number of surface carbons includes unbound surface carbons, carbons bound to nitrogen, and carbons bound to other elements or groups. In any of the aspects or embodiments described herein, the surface nitrogen to carbon ratio is less than or equal to about 0.50, about 0.45, about 0.40, about 0.35, about 0.30, about 0.25, about 0.20, about 0.10, including all overlapping ranges, encompassing ranges, and values therebetween.

[0049] As used herein, the "ratio of surface oxygen of oxidized phosphorus to phosphorus" refers to the ratio of the number of surface phosphorus atoms that are oxidized to the total number of surface phosphorus atoms. The total number of surface phosphorus atoms includes both oxidized and non-oxidized phosphorus atoms. In any of the aspects or embodiments described herein, the ratio of surface oxygen of oxidized phosphorus to phosphorus is less than about 1.0, less than about 0.95, less than about 0.90, less than about 0.85, less than about 0.80, less than about 0.75, less than about 0.70, less than about 0.65, less than about 0.60, less than about 0.55, less than about 0.50, less than about 0.45, less than about 0.40, less than about 0.35, less than about 0.30, less than about 0.25, less than about 0.20, less than about 0.15, less than about 0.10, from about 0.01 to less than about 1.0, from about 0.10 to less than about 1.0, from about 0.05 to less than about 1.0, from about 0.01 to less than about 0.95, from about 0.01 to less than about 0.90, from about 0.01 to less than about 0.85, from about 0.01 to less than about 0.80, from about 0.01 to less than about 0.75, from about 0.01 to less than about 0.70, from about 0.01 to less than about 0.65, from about 0.01 to less than about 0.60, from about 0.01 to less than about 0.55, from about 0.01 to less than about 0.50, from about 0.01 to less than about 0.45, from about 0.01 to less than about 0.40, from about 0.01 to less than about 0.35, from about 0.01 to less than about 0.30, from about 0.01 to less than about 0.25, from about 0.01 to less than about 0.20, and includes all overlapping ranges, inclusive ranges, and values therebetween.

[0050] The structure includes metal species deposited on a substrate comprising an active adsorbent material. The metal species can be derived from a metal species precursor. The metal species precursor can include at least one metal and at least one ligand. The metal species precursor can include at least one metal and at least one ligand having the ability to be replaced, and the metal can form a bond with a functional group on the surface of the active adsorbent material. The metal species can include a single metal or multiple metals. The metal species can include metals such as Li, Be, Mg, Ca, Sr, Ba, Sc, Y, La, Ti, Zr, Hf, Ce, V, Nb, Ta, Pr, Cr, Mo, W, Nd, Mn, Fe, Ru, Sm, Co, Rh, Ir, Ni, Pd, Pt, Gd, Cu, Ag, Zn, Cd, B, Al, Ga, In, Si, Sn, Pb, P, Sb, and Bi; metal oxides such as titanium oxide, copper oxide, cerium oxide, phosphorus oxide, hafnium oxide, aluminum oxide, zirconium oxide, zinc oxide, silicon oxide, tantalum oxide, tungsten oxide, and vanadium oxide; perovskites having the formula ABO3 (such as CaTiO3); metal oxide phosphates or metal phosphates such as vanadium phosphate oxide (VPO), FePO4, and silica phosphate; polyoxometalates such as molybdates, tungstates, antimonates, and vanadates; noble metals, and noble metal compounds such as Ru, Pt, Pd, PdO; organometallic compounds such as metal sulfides, metal nitrides, metal phosphides, metal alkyl compounds, cyclopentadienyl compounds, and metallocenes (e.g., Al(CH3)3, MeCpPtMe3, ferrocene), or any combination thereof. In any of the aspects or embodiments described herein, the metal precursor includes palladium hexafluoro-acetylacetonate or bis(2,2,6,6-tetramethyl-3,5-heptanedionato)palladium(II).

[0051] The metal species deposited on the surface of the active sorbent material can be in the form of a layer or a coating. As used herein, the terms "film", "layer", and "coating" include not only complete films, layers, or coatings (i.e., continuous), but also partial films, layers, or coatings (i.e., incomplete, or not continuous or uniform). The layer containing the metal species can be disposed directly on the surface of the substrate without an intervening layer. The structure can include a single layer or multiple layers. In any of the aspects or embodiments described herein, the structure includes 0 to 10 layers, 1 to 10 layers, 0 to 5 layers, 1 to 5 layers, 2 to 10 layers, 2 to 8 layers, 2 to 5 layers, or 2 to 4 layers.

[0052] Based on the total weight of the structure, the structure can include from about 0.1 to about 50 weight percent, or from about 0.5 to about 50 weight percent, of the metal of the metal species. Based on the total weight of the structure, the structure can include from about 0.5 to about 45 weight percent, from about 0.5 to about 40 weight percent, from about 0.5 to about 35 weight percent, from about 0.5 to about 30 weight percent, from about 0.5 to about 25 weight percent, from about 0.5 to about 20 weight percent, from about 0.5 to about 15 weight percent, from about 0.5 to about 10 weight percent, or from about 0.5 to about 5 weight percent of the metal of the metal species. In any of the aspects or embodiments described herein, when the structure includes titanium(IV) oxide as the metal species, the structure includes from about 0.5 to about 50 weight percent titanium based on the total weight of the structure.

[0053] The structure is not limited to any particular use. Non-limiting examples of uses of the structures disclosed herein include applications in catalysis, filtration, antibacterial, antifungal, photoelectrochemical, antifungal, chemisorption, antiviral, textiles, ceramics, biotechnology, biomedicine, fuel cell systems, semiconductors, microelectronics, optics, and gas storage.

[0054] In an additional aspect, the present specification provides a method for preparing a structure by a process comprising: (a) providing in a reactor a substrate comprising an active adsorbent material, such as a porous active adsorbent material (e.g., activated carbon); and (b) performing or carrying out at least one atomic layer deposition cycle to deposit a metal species, such as a metal oxide, the at least one atomic layer deposition cycle comprising: (i) introducing a first precursor gas into the reactor to provide a metal species precursor deposited on the surface of the active adsorbent material; and (ii) introducing a second precursor gas into the reactor to provide a structure, and the process comprising repeating step (b) from 2 to about 10 times in any aspect or embodiment.

[0055] In any aspect or embodiment described herein, a structure prepared by atomic layer deposition (ALD) is a porous metal-coated structure.

[0056] The first precursor gas can comprise at least one metal and at least one ligand. The at least one ligand can have the ability to be replaced by surface functional groups of the active adsorbent material. The at least one ligand can have the ability to be replaced by atoms provided by a second precursor gas (e.g., O, H). In any of the aspects or embodiments described herein, the first precursor gas comprises a metal halide, a metal oxyhalide, a metal alkoxide, an organometallic compound such as an aluminum alkyl compound (e.g., Al(CH3)3), a metal alkene compound, a metal alkyne compound, a cyclopentadienyl compound (e.g., MeCpPtMe3), and a metallocene (e.g., ferrocene), hexafluoro-acetylacetonate, or a combination thereof. In any of the aspects or embodiments described herein, the first precursor gas comprises titanium chloride, titanium oxychloride, a titanium alkoxide, or a combination thereof. In any of the aspects or embodiments described herein, the first precursor gas comprises hexafluoro-acetylacetone.

[0057] The second precursor gas can replace at least one ligand of the metal species precursor deposited on the surface of the active adsorption material (e.g., oxidation, reduction). The second precursor gas can include a nitrogen-containing precursor gas (such as ammonia, 1,1-dimethylhydrazine, tert-butylamine, or allylamine), a sulfur-containing precursor gas (such as hydrogen sulfide), an oxygen-containing precursor gas (such as H2O, H2O2, O2, O3, or alcohol), a phosphorus-containing precursor gas (such as phosphine gas or P(O)OMe3), a hydrogen-containing gas (such as hydrogen gas), formalin, or a combination thereof. In any of the aspects or embodiments described herein, the second precursor gas can replace at least one ligand of a metal halide, a metal oxyhalide, a metal alkoxide, or a combination thereof. In an exemplary embodiment, the second precursor can replace at least one halogen of a metal halide. The second precursor gas can include an oxidizing agent. The second precursor gas can include a reducing agent. In any of the aspects or embodiments described herein, the second precursor gas includes H2O, H2O2, O2, O3, N2O, NO, NO2, NH3, ammonia, 1,1-dimethylhydrazine, tert-butylamine, or allylamine, alcohol, PH3, P(O)OMe3, hydrogen sulfide, H2, ambient air, formalin, or a combination thereof.

[0058] In any of the aspects or embodiments described herein, the first precursor gas includes palladium hexafluoro-acetylacetonate, and the second precursor gas includes formalin. In any of the aspects or embodiments described herein, the first precursor gas includes bis(2,2,6,6-tetramethyl-3,5-heptanedionato)palladium(II), and the second precursor gas includes ambient air.

[0059] In the method of the present disclosure, step b can be carried out at least twice, or 2 to 4 times.

[0060] The method is generally carried out under a vacuum pressure. The vacuum pressure is selected such that the first precursor gas is solid or liquid (and does not substantially vaporize) at room temperature. The first precursor can be heated to generate the first precursor gas. The second precursor can be heated to generate the second precursor gas. In an alternative embodiment, the second precursor gas is ambient air. The reactor can be opened to the atmosphere to expose the metal species precursor in the reactor to ambient air to oxidize the metal species precursor to a metal species. The method can include the foregoing combinations.

[0061] The method can include introducing an additional second precursor gas that is different from the second precursor gas introduced in step (b)(ii) of the method of the present disclosure. The additional second precursor gas can be used to convert the functional group bonded to the metal of the metal species to a different functional group.

[0062] The method can also include a purging step following step (b)(i) in which the first precursor gas is introduced, step (b)(ii) in which the second gas is introduced, or a combination thereof. The purging can be carried out using a vacuum, using an inert gas, or a combination thereof. The purging step can remove unreacted precursor gases and by-products from the reaction of the first precursor gas with the activated adsorbent material and / or the reaction of the second precursor gas with the metal species precursor deposited on the surface of the activated adsorbent material.

[0063] In any aspect or embodiment described herein, a method for preparing a modified activated adsorbent material includes (a) providing activated carbon in a reactor and (b) performing at least one atomic layer deposition cycle, the step of performing at least one atomic layer deposition cycle including (i) introducing TiCl4 gas into the reactor and (ii) introducing water vapor into the reactor to provide titanium oxide modified activated carbon.

[0064] Activated carbon powder modified with titanium oxide has excellent catalytic activity as determined by the 2-propanol temperature-programmed desorption (TPD) spectrum, compared to AEROXIDE® P25 TiO2 (commercially available from Evonik (Hanau-Wolfgang, Germany)). For a more detailed description, see Yi Y. Wu, Harold H. Kung, Probing properties of the interfacial perimeter sites in TiOx / Au / SiO2 with 2-propanol decomposition, Applied Catalysis A: General, Volume 548, 2017, Pages 150-163, which is incorporated by reference.

[0065] TPD of 2-propanol is widely used to characterize oxide surfaces. 2-Propanol is widely observed to disproportionate on oxide surfaces by both dehydrogenating to acetone and dehydrating to propene. The catalytic activity of the deposited TiO2 was characterized by comparing the yields of acetone and propene to those from P25.

[0066] In any of the described aspects or embodiments, the atomic layer deposition apparatus comprises a vacuum manifold, containers for each of a first precursor, a second precursor, and activated carbon, a vacuum pump, a cold trap, at least one heat source, and a heating controller. The vacuum manifold has a line with a valve connected to a manifold for a first precursor gas, a second precursor gas, and an activated carbon substrate; and containers for each of the first precursor, the second precursor, and the activated carbon substrate, each connected to a respective line of the manifold. The manifold and containers can be heated for efficient transfer of the precursor gas to the activated carbon.

[0067] In any of the described aspects or embodiments, the atomic layer deposition method can be performed in a suitable apparatus for batch mode, semi - continuous mode, continuous mode, or combinations thereof. In any of the aspects or embodiments described herein, the apparatus includes a fluidized bed reactor. Of course, the structure can be formed using any of the apparatuses known to those skilled in the art.

Example

[0068] Unless otherwise specifically indicated, the amount of each component is a weight percentage (wt%) based on the total weight of the composition.

[0069] The bulk nitrogen - to - carbon ratio, phosphorus - to - carbon ratio, and oxygen - to - carbon ratio of the substrate may be measured using energy - dispersive spectroscopy (EDS). The EDS Spectra were provided by Electral Analysis, Inc (Lexington, Kentucky, USA). Each sample was attached to carbon tape. For each sample analyzed, spectra were obtained using an Oxford X - Max 80 energy - dispersive spectrometer at three different sites. The spectra were acquired at 500× and 1,000× with an excitation voltage of 30 kV. The surface oxygen density may be measured using beam titration, Auger electron spectroscopy (AE), X - ray photoelectron spectroscopy (XPS), or low - energy ion scattering spectroscopy (LEIS). The metal filling may be measured using Auger electron spectroscopy (AE), atomic absorption spectroscopy (AAS), energy - dispersive spectroscopy (EDS), inductively coupled plasma spectroscopy (ICP), LEIS, or XPS.

[0070] [Example 1] ALD of TiO2 on activated carbon powder and catalyst characterization Example 1 describes the ALD of TiO2 on activated carbon powder and compares its performance with TiO2 powder. The activated carbon powder was NUCHAR® RGC (Ingevity South Carolina, LLC, North Charleston, South Carolina, USA) and had a d50 of 18.3 microns. The TiO2 powder was AEROXIDE® P25 (Evonik, Germany, Hanau-Wolfgang) and had a d50 of 2.95. The ALD apparatus was constructed in line with Figure 1. The apparatus included a vacuum manifold, a cold trap (104), a vacuum pump (105), and three feed lines with valve controls (107, 108, 109). The three feed lines were connected to flasks (101, 102, and 103) for the reaction precursors: activated carbon, TiCl4 (titanium(IV) chloride 99.9%, obtained from Sigma Aldrich), and the oxidizing agent (water). The manifold was coated with heating tape so that the manifold temperature was 200 °C. Activated carbon (2 g) was loaded into the flask, the flask was connected to the vacuum manifold, and the activated carbon was held at 150 °C for 2 hours to allow unrestricted deposition of TiCl4 and partial oxidation at the active sites, at about 10 -3It was evacuated to a vacuum pressure of Torr to remove contaminants. For example, when H2O remains on the surface, TiCl4 will be highly processable for excessive oxidation / deposition (CVD) and is also likely not to be fixed on the surface. The flask was cooled to room temperature, removed from the vacuum, and weighed to record the weight loss. The flask was attached to the manifold and evacuated overnight at room temperature. TiCl4 (5 mL) was added to a vial connected to the vacuum manifold. The vapor space in the vial was evacuated three times to equilibrate the contents of the vial between vacuum pulses. TiCl4 vapor (heated to 80 °C) was introduced into the reaction flask containing activated carbon at 150 °C by opening valves 108, 109, and 110, whereby the vacuum became less than 50 mTorr. Valve 110 was closed after 5 seconds. After 2 hours, valve 108 was closed and valve 110 was slowly reopened. The reaction flask was evacuated for 2 hours. The manifold was removed from the vacuum so as to be open to air. The vial containing water was heated to 60 °C and valves 107, 109, and 110 were opened to allow humid air to flow through the entire reaction flask or through the reaction flask. After 2 hours, the heating was removed and the manifold was left open to air overnight. The process was repeated three more times.

[0071] Figure 2 shows the results of the gravimetric analysis of activated carbon powder modified with titanium oxide after 1 - 4 cycles of ALD.

[0072] Figures 3A - 3D show the weight % of TiO2 for activated carbon powder modified with titanium oxide after 0 - 4 cycles of ALD.

[0073] Figures 4A - 4D are SEM images of activated carbon powder modified with titanium oxide after 0 - 4 cycles of ALD.

[0074] Figure 5 shows the TiO2 growth rate through 4 ALD cycles for activated carbon powder modified with titanium oxide.

[0075] Characterization method of TiO2 - modified RGC using temperature - programmed desorption.

[0076] To characterize the catalytic activity of the TiO2-modified RGC carbon sample, an in-situ temperature-programmed desorption setup and technique were developed. The TPD setup consists of a GC-MS (Shimadzu GCMS-QP2010S) connected to the exhaust port of a thermogravimetric analyzer (Perkin Elmer TGA 8000). The column in the GC-MS was bypassed, and the exhaust gas was injected directly into the GC-MS for real-time analysis of the TGA products. The sample was loaded into the TGA and saturated with 2-propanol. The 2-propanol-saturated sample was maintained at 25 °C for 30 min in N2 at 20 ml / min to remove excess 2-propanol. The sample was heated at 10 °C / min while simultaneously monitoring the desorption products using the GC-MS.

[0077] TiO2-modified RGC and commercially available P25 TiO2 were tested using the above-described characterization method. The 2-propanol temperature-programmed desorption spectra (TPD spectra) for each are shown in FIGS. 6A-6C. The desorption peaks were integrated to quantify the product yields. The desorption products were identified by their characteristic fragmentation patterns. The calculated mass spectrometer sensitivity coefficients were used to quantify the product yields. The characteristic masses (m / z) used to quantify the products from 2-propanol TPD were 45 (2-propanol), 18 (H2O), and 41 (propene). A comparison of the product spectra from 2-propanol TPD is shown in FIGS. 7A-7B. The acetone and propene yields from the TPD method are summarized in Table 1, which shows the excellent performance of the TiO2-modified RGC after 4 rounds of ALD.

[0078] [Table 1]

[0079] [Example 2] ALD of TiO2 on Granular Activated Carbon Example 2 describes the ALD of TiO2 on several activated carbons and graphites. All of the activated carbons and graphites were screened to a particle size of 20×60 mesh. The activated carbons included chemically activated, wood-based carbons from NUCHAR® (Ingevity South Carolina LLC, North Charleston, South Carolina, USA). These carbons were NUCHAR® RGC, NUCHAR® AquaGuard (AG), NUCHAR® BAX 1500, and NUCHAR® WV-A 1100. Thermally activated, coconut-based carbon (20×50 mesh, acid-washed, 85 - 90 CTC (Carbon Activated Corp, Compton, California, USA)), and graphite (SAG20 (MTI Corporation, Richmond, California, USA)) were also used. For tests using oxidized samples, both graphite and RGC were oxidized by placing each carbon in a beaker containing 70% nitric acid (Sigma-Aldrich). The carbon-to-nitric acid ratio was 1:10. The beaker containing the acid and carbon was heated to 80 °C and then stirred for 3 hours. The carbon was then removed from the acid using vacuum filtration. The filtered carbon was washed with distilled water until the pH was >5. The carbon was then placed in an oven at 110 °C overnight. Table 2 shows the BET surface area and pore volume for each of these carbons. Before subjecting the carbon to ALD, the carbon was analyzed by XPS for C, O, N, and P content, and the results are shown in Figure 10 and summarized in Table 3. Figures 9A - 9C show SEM photographs of unused WV-A1100 (Figure 9A), BAX1500 (Figure 9B), and graphite (Figure 9C).

[0080]

Table 2

[0081]

Table 3

[0082] The ALD device was constructed in alignment with Figure 8. The device includes a heated feed line with valve control in series with a vacuum pump. To generate humid air, the feed line was connected to a steam generator connected to a syringe filled with water. Air was introduced into the heated trace line. As shown in Figure 8, TiCl4 was present in one column and carbon was present in a second column. Prior to deposition, the device was evacuated overnight under a vacuum pressure of about 10 -3 Torr at room temperature by closing valve 906 and opening valves 908 and 909. The traced line was heated to 200 °C, and the columns containing TiCl4 and carbon were heated to 80 °C and 150 °C, respectively. To deposit TiCl4 on carbon, valve 909 was closed and valves 907 and 908 were opened for 2 hours. After 2 hours, valve 907 was closed and valve 909 was slowly reopened. The device was evacuated for 2 hours. Thereafter, valve 906 was opened to allow humid air to flow through the carbon column. After 2 hours, the heating was removed and the manifold was left open to air overnight. The process was repeated once more, but it can be repeated 2 - 4 times.

[0083] After 2 cycles of ALD using TiO2, the estimated surface coverage was calculated assuming monolayer coverage according to the following equation. (For example, Luo and a).

Equation

[0084] where ρ TiO2 is the bulk density of TiO2 (m3 / g), the carbon S.A. is the BET surface area (m2 / g), and α is the characteristic length of the TiO2 unit cell (lattice parameter, m).

[0085] Figure 11 shows a comparison of the estimated surface coverage of coconut, oxidized RGC, RGC, WVA1100, AquaGuard (AG), and graphite after varying ALD cycles. For the estimations presented in this figure, it is assumed that TiO2 is deposited as the rutile phase. This figure shows that the rate of TiO2 ALD is greatest for coconut and follows the order coconut > oxidized RGC, Aquaguard, WV-A 1100 RGC > graphite. Additionally, surface oxidation enhanced the deposition rate of TiO2 (comparing oxidized RGC to RGC).

[0086] Figures 12A - 12C show SEM images and XRD of oxidized RGC, AG, and graphite after 2 cycles of TiO2 ALD. Oxidized RGC had a higher incorporation of TiO2 compared to AG (non-oxidized). Graphite had very poor incorporation of TiO2.

[0087] Figure 13 shows the XPS spectra of WV-A 1100 before and after TiO2 ALD. The unused material is the bottom trace, the material after 1 cycle of ALD is the middle trace, and the material after 2 cycles of ALD is the top trace.

[0088] Figure 14 shows the XPS spectra of coconut, 1100, and RGC after 2 cycles of TiO2 ALD. RGC after 2 cycles of ALD is the bottom trace, 1100 after 2 cycles of ALD is the next highest trace, and coconut after 2 cycles of ALD is the top trace. The O1s peak corresponds to metal oxides. The Ti(2p) peaks at 2p3 / 2 and 2p1 / 2 correspond to fully oxidized Ti atoms (TiO2 formation).

[0089] Figure 15 shows the results of the butane isotherms for WVA1100 before and after TiO2 ALD. Figure 15A shows the isothermal results based on the total weight of the samples. The unused material is the top trace, the material after 1 cycle of ALD is the middle trace, and the material after 2 cycles of ALD is the bottom trace. After normalizing on a carbon weight basis, as shown in Figure 15B, there is substantial overlap in the plots of the unused material, the 1-cycle material, and the 2-cycle material.

[0090] [Example 3] Catalytic Characterization of TiO2-Modified Granular Carbon Using Temperature-Programmed Desorption (TPD) To test the catalytic activity of the TiO2-modified carbon samples, an in-house desorption setup and technique were developed. The TPD setup included a GC-MS (SHIMADZU GCMS-QP2010S) connected to the exhaust port of a thermogravimetric analyzer (PERKIN ELMER TGA 8000). The column in the GC-MS was bypassed, and the exhaust gas was injected directly into the mass spectrometer for real-time analysis of the TGA products. The sample was loaded into the TGA and saturated with 2-propanol. Nitrogen(g) was passed through at 20 mL / min for 30 minutes at 25 °C to remove excess 2-propanol, and the sample was heated at 10 °C / min while monitoring the desorption products with the mass spectrometer. The desorption products were identified by their characteristic fragmentation patterns. The product signals were corrected by their sensitivity coefficients. The characteristic masses (m / z) used to quantify the products from 2-propanol were 45 (2-propanol), 18 (H2O), and 41 (propene).

[0091] Figures 16A - 16B show the TPD spectra after 2 cycles of TiO2-ALD for WV-A1100 and RGC, respectively. For each of Figures 16A - 16B, the spectra of the ALD-modified materials are overlaid with those of the unused materials. The lower curves for acetone, CO2, and propene are for the materials subjected to 1 cycle of ALD, and the upper curves are for each of acetone, CO2, and propene after the second cycle of ALD.

[0092] Figure 17 shows the TPD spectrum of TiO2-modified graphite. No reaction products were detected, and rapid desorption was observed due to the lack of porosity in the material.

[0093] Figure 18 shows the TPD spectrum of TiO2-modified AQUAGUARD. The peak at 120 indicates reactive intermediates, and the oxygen of 2-propanol is bonded to titanium.

[0094] Figure 19 shows the TPD spectrum of TiO2-modified RGC oxide. Acetone and propene reaction products were detected.

[0095] [Example 4] Palladium Deposition on WV-A 1100 Pd deposition was carried out using palladium hexafluoro-acetylacetonate as the first precursor gas. The sample oven was set to 110 °C, a carbon sample was placed stationary in the sample column, the line heater was set to 180 °C, and it was evacuated for 2 hours. The sample oven and line heater were cooled to 70 °C. Palladium hexafluoro-acetylacetonate was added to the sample column. The vacuum pressure was re-established for 2 minutes by opening valve 909. At this point, valve 909 was closed, and precursor deposition was allowed to proceed for 30 minutes. After deposition, valve 909 was reopened, and the sample was evacuated using the following temperature ranges and times: (1) deposition at 70 °C for 30 minutes, (2) evacuation at 70 °C for 30 minutes, 110 °C for 30 minutes, and 180 °C for 2 hours. The line heater was heated to 180 °C, and the sample oven was left at 180 °C. Then, the sample column was opened to the atmosphere by opening valves 906 and 908, and 37% formalin (the second precursor gas) was pumped through the vapor generator using a nitrogen flow set to 500 sccm. This formalin was pumped through the system for 1 hour. When complete, the sample was removed and left in an oven at 110 °C overnight.

[0096] Figures 20A - 20C show SEM photographs and XRD of WV - A 1100 after 1 cycle of Pd ALD (Figure 20A), 2 cycles of ALD (Figure 20B), and 4 cycles of ALD (Figure 20C).

[0097] Figure 21 shows XPS of the Pd - modified samples of WV - A 1100 after 1, 2, and 4 cycles of ALD. The bottom trace is the unused material, the next trace above is after 1 cycle of ALD, the next trace above is after 2 cycles of ALD, and the top trace is after 4 cycles of ALD. The peak at 339.8 corresponds to Pd. It is clear that the peak at 335.8 eV increases with the number of ALD cycles.

[0098] Figure 22 shows the weight % of Pd deposited on WV - A 1100 after 1 cycle (1.29 wt%), 2 (2.84 wt%), and 4 cycles (5.21 wt%) of ALD.

[0099] The activity of the catalyst was tested with the reaction with abietic acid. Abietic acid has been shown to be easily converted to dehydroabietic acid in the presence of a conventional Pd catalyst (Linlin Wang, Xiaopeng Chen, Wenjing Sun, Jiezhen Liang, Xu, Zhangfa Tong, Kinetic model for the catalytic disproportionation of pine oleoresin over Pd / C catalyst, Industrial Crops and Products, Volume 49, 2013, pp. 1 - 9). The catalytic activity of the deposited Pd was characterized by evaluating the rate of disappearance of abietic acid and the rate of formation of the corresponding dehydroabietic acid. Figure 23 shows the disappearance of abietic acid over time. The two overlapping curves are the reactions without catalyst and the reaction of the unused material. The bottom curve corresponds to the reaction of abietic acid in the presence of the Pd - modified material (i.e., the catalyst) obtained after 2 cycles of ALD. The upper curve corresponding to the reaction of abietic acid in the presence of the Pd - modified material (i.e., the catalyst) was obtained after 1 cycle of ALD.

[0100] The activity of the catalyst (i.e., Pd deposited on WV - A 1100) was tested with the alcohol dehydrogenation reaction with 2 - propanol. Figure 24A shows the TGA spectra using air and N2. Figure 24B shows the evolved gas spectra.

[0101] [Example 5] Palladium Deposition on Other Carbons Pd deposition was carried out as described in Example 4.

[0102] Figure 25A shows the SEM photograph of graphite after 2 cycles of Pd ALD at a magnification of 10,000×. Figure 25B shows the SEM photograph of graphite after 2 cycles of Pd ALD at a magnification of 100,000×.

[0103] FIG. 26A shows an SEM photograph of graphite oxide after 2 cycles of Pd ALD at a magnification of 10,000×. FIG. 26B shows an SEM photograph of graphite after 2 cycles of Pd ALD at a magnification of 100,000×.

[0104] FIGS. 27A-27B show XPS of graphite and graphite oxide before and after 2 cycles of ALD. The bottom trace is unused graphite, and the upper trace is after the second cycle of ALD (FIG. 27A). Similarly, the upper trace is unused graphite oxide, and the upper trace is after the second cycle of ALD (FIG. 27A). FIG. 27B shows that there is no peak in the region corresponding to Pd. The absence of the detected Pd peak indicates that the deposition of Pd via ALD failed both on graphite oxide and on graphite.

[0105] The PIXE analysis of the Pd-modified carbon samples is summarized in Table 4 below.

[0106] [Table 4]

Claims

1. A structure comprising a substrate including an active adsorbent material and a metal species deposited thereon.

2. The structure according to claim 1, wherein the metal species deposited thereon is a film, a layer, or a coating.

3. The structure according to claim 1 or 2, wherein the active adsorbent material is not additionally modified other than activation.

4. The structure according to any one of claims 1 to 3, wherein the active adsorbent material includes activated carbon, charcoal, nanostructured carbon, expanded graphite, graphene, zeolite, clay, porous polymer, porous alumina, porous silica, molecular sieve, kaolin, titania, ceria, or a combination thereof.

5. The structure according to any one of claims 1 to 4, wherein the active adsorbent material includes activated carbon in the form of powder, granule, pellet, monolith, or honeycomb.

6. The structure according to claim 5, wherein the activated carbon is derived from at least one of wood, wood dust, wood flour, cotton linter, peat, coal, coconut, lignite, carbohydrate, petroleum pitch, petroleum coke, coal tar pitch, fruit pit, fruit stone, nut shell, nut pit, sawdust, palm, vegetable, synthetic polymer, natural polymer, lignocellulosic material, or a combination thereof.

7. The structure according to claim 5 or 6, wherein the activated carbon is activated using activation including at least one of phosphoric acid, sulfuric acid, boric acid, nitric acid, oxygenated acid, steam, air, peroxide, alkali hydroxide, metal chloride, ammonia, carbon dioxide, or a combination thereof.

8. The structure according to any one of claims 1 to 7, wherein the active adsorbent material is characterized by a mesoporous pore size, a macroporous pore size, or a combination thereof.

9. The structure according to any one of claims 1 to 8, wherein the active adsorbent material is characterized by a nitrogen B.E.T. surface area of about 600 to about 2500, or about 800 to about 1800, or about 1000 to about 1600 square meters per gram.

10. The structure according to any one of claims 5 to 7, wherein the activated carbon has a bulk oxygen-to-carbon ratio of about 0.25 or less at a depth of less than 5 nm.

11. The structure according to any one of claims 5 to 7 or claim 10, wherein the activated carbon has a bulk phosphorus-to-carbon ratio of about 0.10 or less at a depth of less than 5 nm.

12. The structure according to any one of claims 5 to 7, claim 10, or claim 11, wherein the activated carbon has a bulk nitrogen-to-carbon ratio of about 0.15 or less at a depth of less than 5 nm.

13. The structure according to any one of claims 5 to 7 or claims 10 to 12, wherein the activated carbon has a surface oxygen-to-carbon ratio of about 1 or less based on the total number of surface carbons.

14. The structure according to any one of claims 5 to 7 or claims 10 to 13, wherein the activated carbon has a surface phosphorus-to-carbon ratio of about 0.33 or less based on the total number of surface carbons.

15. The structure according to any one of claims 5 to 7 or claims 10 to 14, wherein the activated carbon has a surface nitrogen-to-carbon ratio of about 0.5 or less based on the total number of surface carbons.

16. The structure according to any one of claims 5 to 7 or claims 10 to 15, wherein the activated carbon has a ratio of surface oxygen to phosphorus of oxidized phosphorus of about 1.0 or less based on the total number of surface phosphorus atoms.

17. The structure according to any one of claims 1 to 16, wherein the metal species is derived from a metal species precursor containing at least one metal and at least one ligand.

18. The structure according to any one of claims 1 to 17, wherein the metal species includes a metal, a metal oxide, a metal oxide phosphate, a polymetal oxide, a perovskite, a metal sulfide, a metal nitride, a metal phosphide, an organometallic compound, or a combination thereof.

19. The structure according to any one of claims 1 to 18, wherein the metal species includes titanium oxide.

20. The structure according to any one of claims 1 to 19, wherein the metal species includes palladium.

21. The structure according to any one of claims 1 to 20, wherein the structure includes about 0.5 to about 50 wt% of the metal species based on the total weight of the structure.

22. a. providing an active adsorbent material in a reactor; b. performing at least one atomic layer deposition cycle to deposit a metal species, wherein the step of performing the at least one atomic layer deposition cycle includes: i. introducing a first precursor gas into the reactor to provide a metal species precursor deposited on the surface of the active adsorbent material; and ii. introducing a second precursor gas into the reactor to provide a structure, and a method for preparing a structure according to a process including this process.

23. The method according to claim 22, wherein step b is performed 2 to 10 times.

24. The method according to claim 22 or claim 23, further comprising a step of purging the reactor after step (b)(i), step (b)(ii), or a combination thereof.

25. The method according to any one of claims 22 to 24, wherein the active adsorbent material comprises activated carbon, carbonized charcoal, nanostructured carbon, expanded graphite, graphene, zeolite, clay, porous polymer, porous alumina, porous silica, molecular sieve, kaolin, titania, ceria, or a combination thereof.

26. The method according to any one of claims 22 to 25, wherein the first precursor gas comprises at least one metal and at least one ligand.

27. The method according to any one of claims 22 to 26, wherein the first precursor gas comprises a metal halide, a metal oxyhalide, an organometallic compound, or a combination thereof.

28. The method according to any one of claims 22 to 27, wherein the second precursor gas has the ability to replace the ligand of the metal species precursor deposited on the surface of the active adsorbent material.

29. wherein the second precursor gas is H ２ O, H ２ O ２ 、O ２ 、O ３ 、N ２ O, NO, NO ２ 、NH ３ 、ammonia, 1,1-dimethylhydrazine, tert-butylamine, or allylamine, alcohol, PH ３ 、P(O)OMe ３ 、hydrogen sulfide, H ２ 、ambient air, formalin, or a combination thereof, the method according to any one of claims 22 to 28.

30. The method according to any one of claims 22 to 29, wherein the active adsorbent material is derived from at least one of wood, wood dust, wood flour, cotton linter, peat, coal, coconut, lignite, carbohydrate, petroleum pitch, petroleum coke, coal tar pitch, fruit pit, fruit stone, nut shell, nut pit, sawdust, palm, vegetable, synthetic polymer, natural polymer, lignocellulosic material, or a combination thereof.

31. The method according to any one of claims 22 to 30, wherein the active adsorbent material is characterized by a nitrogen B.E.T. surface area of about 600 to about 2500, or about 800 to about 1800, or about 1000 to about 1600 square meters per gram.

32. The method according to any one of claims 22 to 31, wherein the adsorbent material comprises activated carbon in powder, granule, pellet, monolith, or honeycomb form.

33. The method according to claim 32, wherein the activated carbon has a bulk oxygen-to-carbon ratio of about 0.25 or less at a depth of less than 5 nm.

34. The method according to claim 32 or claim 33, wherein the activated carbon has a bulk phosphorus-to-carbon ratio of about 0.10 or less at a depth of less than 5 nm.

35. The method according to any one of claims 32 to 34, wherein the activated carbon has a bulk nitrogen-to-carbon ratio of about 0.15 or less at a depth of less than 5 nm.

36. The method according to any one of claims 32 to 35, wherein the activated carbon has a surface oxygen-to-carbon ratio of about 1.0 or less based on the total number of surface carbons.

37. The method according to any one of claims 32 to 36, wherein the activated carbon has a surface phosphorus-to-carbon ratio of about 0.33 or less based on the total number of surface carbons.

38. The method according to any one of claims 32 to 37, wherein the activated carbon has a surface nitrogen-to-carbon ratio of about 0.5 or less based on the total number of surface carbons.

39. The method according to any one of claims 32 to 38, wherein the activated carbon has a surface oxygen-to-phosphorus ratio of oxidized phosphorus of about 1.0 or less based on the total number of surface phosphorus atoms.

40. a. providing activated carbon powder in a reactor; b. performing at least one atomic layer deposition cycle to deposit a metal species containing titanium oxide, wherein performing the at least one atomic layer deposition cycle comprises: i. Introduce TiCl ４ gas into the reactor to provide titanium chloride deposited on the surface of the activated carbon powder, and ii. introducing water vapor or ambient air into the reactor to provide the titanium oxide deposited on the surface of the activated carbon powder; and

41. a. the active adsorbent material is activated carbon powder; b. the metal species contains palladium; c. the first precursor gas is palladium hexafluoro-acetylacetone; d. the second precursor gas is formalin or ambient air; or e. at least one of combinations thereof, the method according to claim 22.

42. a. providing activated carbon powder in a reactor; b. performing at least one atomic layer deposition cycle to deposit a metal species containing palladium, wherein performing the at least one atomic layer deposition cycle comprises: i. introducing bis(2,2,6,6-tetramethyl-3,5-heptanedionato)palladium(II) into the reactor to provide a palladium intermediate deposited on the surface of the activated carbon powder; and ii. introducing ambient air into the reactor to provide the palladium deposited on the surface of the activated carbon powder; and

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