Amorphous carbon graphite structure precursors

Abstract

The invention relates to an amorphous carbon graphite structure precursor. A carbon precursor for manufacturing a carbon support having a graphite structure. The carbon precursor may include defective amorphous carbon spheres having a mass loss percentage compared to non-defective amorphous carbon spheres. The defective amorphous carbon spheres can form a single-layer graphite structure for use as a carbon support. The carbon graphite structure precursor may include amorphous carbon nanoclusters having a nominal nanocluster diameter of less than 3 nanometers. The amorphous carbon nanoclusters can form a single-layer graphite structure for use as a carbon support.

Description

Technical Field

[0001] The present disclosure relates to precursors of amorphous carbon graphite structures (e.g., precursors of amorphous carbon monolayer graphite structures). The precursors of amorphous carbon graphite structures can be used to form monolayer graphite structures and serve as catalyst supports in proton exchange membrane fuel cells (PEMFCs) and other electrochemical cells. Background Art

[0002] Proton exchange membrane fuel cells (PEMFCs) are an environmentally friendly energy conversion device. Utilizing the electrochemical reaction of H2 and O2 gases, PEMFCs provide an actual energy efficiency of over 60%, where H2O is the only product. The rapid diffusion of H- ions enables PEMFCs to operate properly even at relatively low temperatures of about 100 °C. In contrast, solid oxide fuel cells and molten carbonate fuel cells operate at about 600 °C and higher temperatures.

[0003] Despite the advantages of PEMFCs, their high production cost and relatively poor durability limit their applications in energy plants and more cost - effective transportation technologies. For example, the cost of the platinum (Pt) / carbon (C) electrocatalyst in the cathode of PEMFCs is at least half of the production cost of PEMFCs, and the electrochemically active surface area (ECSA) of the Pt catalyst deteriorates severely (e.g., 50% or more) during cycling. Summary of the Invention

[0004] In one embodiment, a carbon precursor for manufacturing a carbon support having a graphite structure is disclosed. The carbon precursor includes defective amorphous carbon spheres having a certain percentage of mass loss compared to defect - free amorphous carbon spheres. The defective amorphous carbon spheres are capable of forming a monolayer graphite structure that serves as a carbon support.

[0005] When the density of the defect - free amorphous carbon spheres is less than 2.5 g / cm 3 ³, the percentage of mass loss can be greater than 70%. When the density of the defect - free amorphous carbon spheres is greater than 2.5 g / cm 3 ³, the percentage of mass loss can be greater than 80%. The defective amorphous carbon spheres may include defects (e.g., cylindrical defects). The defective amorphous carbon spheres can be defective amorphous carbon nanospheres. The defect - free amorphous carbon spheres may include hollow spheres. The defective amorphous carbon spheres may include micropores with a size less than 2 nanometers, and the range is 0.5 - 2.0 cm 3 / g.

[0006] In another embodiment, a carbon precursor for manufacturing a carbon support having a graphite structure is disclosed. The carbon precursor includes amorphous carbon nanoclusters having a nominal nanocluster diameter of less than 3 nanometers. The amorphous carbon nanoclusters may be capable of forming a monolayer graphite structure that serves as a carbon support.

[0007] The amorphous carbon nanoclusters can have a density of 1 to 1.6 g / cm 3 for the amorphous carbon nanoclusters. When the amorphous carbon nanoclusters have a density of 1.6 to 2.4 g / cm 3 for the amorphous carbon nanoclusters, the nominal nanocluster diameter can be less than 2 nanometers. When the amorphous carbon nanoclusters have a density of 2.4 to 3.0 g / cm 3 for the amorphous carbon nanoclusters, the nominal nanocluster diameter can be less than 1.6 nanometers. The amorphous carbon nanoclusters can include defects.

[0008] In yet another embodiment, a method of manufacturing a single-layer graphite structure for use as a carbon support is disclosed. The method can include annealing amorphous carbon spheres to form a single-layer graphite structure and shaping the single-layer graphite structure into a carbon support.

[0009] When the amorphous carbon spheres are defective amorphous carbon spheres, the method can further include forming defective amorphous carbon spheres from starting amorphous carbon spheres. The forming step can include reducing the mass of the starting carbon spheres by a certain mass loss percentage to obtain defective amorphous carbon spheres. The step can include ion-bombarding the starting carbon spheres. The forming step can include etching the starting carbon spheres. The single-layer graphite structure can be a single-layer graphite shell. The carbon support can be configured to support an electrocatalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 A schematic side view of certain components of a proton exchange membrane fuel cell (PEMFC) according to an embodiment is described.

[0011] Figure 2A A schematic diagram of an amorphous carbon solid sphere that is graphitized into graphite carbon nano-onions is described.

[0012] Figure 2B A schematic diagram of an amorphous carbon hollow sphere that is graphitized into a single-layer graphite carbon hollow shell is described.

[0013] Figure 3A is a plot showing the carbon number per volume vs. the distance from the center of the graphite carbon nano-onions shown having different initial radii (i.e., about and about ) and an initial density of 2.97 g / cm 3 of the initial density Figure 2A .

[0014] Figure 3B is a plot showing the surface area change of nano-onion solid spheres and hollow spheres having different initial radii and an initial density of 2.97 g / cm 3 of the initial density.

[0015] Figure 4A is a plot showing that the density is 1.55 g / cm 3Graph showing the variation of the surface area of nano-onion solid spheres and hollow spheres with the initial sphere radius.

[0016] Figure 4B Shows the graph of the surface area of nano-onion solid spheres and hollow spheres with a density of 2.44 g / cm 3 Graph showing the variation of the surface area of nano-onion solid spheres and hollow spheres with the initial sphere radius.

[0017] Figure 5 Graph describing the surface area of graphitized carbon spheres with different mass losses.

[0018] Figure 6 Schematic diagram of an amorphous carbon sphere with cylindrical defects, with more than 70% of its mass reduced to graphitized single-layer graphite carbon clusters.

[0019] Figure 7A Schematic diagram of an amorphous carbon sphere with a radius of about 0.8 nm graphitized into single-layer graphite carbon clusters.

[0020] Figure 7B Schematic diagram of an amorphous carbon sphere with a radius of about 1.0 nm graphitized into double-layer graphite carbon clusters. Detailed Description

[0021] The embodiments of the present disclosure are described herein. However, it should be understood that the disclosed embodiments are merely examples, and other embodiments may take various and alternative forms. The drawings are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Thus, the specific structural and functional details disclosed herein should not be construed as limiting, but merely as a representative basis for teaching those skilled in the art to employ the embodiments in various ways. As will be understood by those of ordinary skill in the art, the various features shown and described with reference to any one of the drawings may be combined with the features shown in one or more other drawings to produce embodiments not explicitly shown or described. The combinations of the shown features provide representative embodiments for typical applications. However, various combinations and modifications of the features consistent with the teachings of the present disclosure may be desirable for a particular application or implementation.

[0022] Except where otherwise indicated in the examples or otherwise explicitly stated, all numerical quantities representing amounts of materials or numerical quantities of conditions of reaction and / or use in this specification should be understood to be modified by the word "about" when describing the broadest scope of the invention. Practice within the stated numerical ranges is generally preferred. Further, unless explicitly stated to the contrary: percentages, "parts" and ratios are by weight; the description of a given group or class of materials suitable or preferred for a given purpose in connection with the present invention means that a mixture of any two or more members of that group or class is equally suitable or preferred; the description of ingredients in chemical terms refers to the ingredients at the time of addition to any combination specified in the specification and does not necessarily preclude chemical interactions between the ingredients of the mixture once mixed.

[0023] The first definition of an acronym or other abbreviation applies to all subsequent uses of the same abbreviation in this document and, with necessary modifications, to normal grammatical variations of the initially defined abbreviation. Unless explicitly stated to the contrary, measurements of properties are determined by the same techniques as those cited previously or subsequently for the same property.

[0024] It must also be noted that, as used in the specification and the appended claims, the singular forms "a", "an" and "the" include plural referents unless the context clearly indicates otherwise. For example, reference to a single component in the singular is intended to include a plurality of components.

[0025] As used herein, the terms "substantially", "generally" or "about" mean that the quantity or value being discussed can be the specified particular value or some other value near it. Generally, the term "about" when used in reference to a value is intended to mean a range within ± 5% of that value. As an example, the phrase "about 100" means a range of 100 ± 5, i.e., a range from 95 to 105. Generally, when the term "about" is used, it can be expected that similar results or effects according to the present invention can be obtained within the range of ± 5% of the indicated value. The term "substantially" can modify the values or relative characteristics disclosed or claimed in this disclosure. In such cases, "substantially" can mean that the value or relative characteristic being modified is within ± 0%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5% or 10% of that value or relative characteristic.

[0026] It should also be understood that an integer range expressly includes all intermediate integers. For example, the integer range from 1 to 10 expressly includes 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10. Similarly, the range from 1 to 100 includes 1, 2, 3, 4,....97, 98, 99, 100. Similarly, when any range is required, the intermediate numbers that are the difference between the upper and lower limits divided by an increment of 10 can be considered as optional upper or lower limits. For example, if the range is from 1.1 to 2.1, the following numbers 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, and 2.0 can be selected as the lower or upper limits.

[0027] In the examples described herein, the concentration, temperature, and reaction conditions (such as pressure, pH, flow rate, etc.) can be implemented with an indicated value plus or minus 50%, and the value is rounded or truncated to two significant figures of the value provided in the example. In one improvement, the concentration, temperature, and reaction conditions (such as pressure, pH, flow rate, etc.) can be implemented with plus or minus 30% of the following values, and the values are shown as rounded or truncated to two significant figures of the value provided in the example. In another improvement, the concentration, temperature, and reaction conditions (such as pressure, pH, flow rate, etc.) can be implemented with plus or minus 10% of the following values, and the values are shown as rounded or truncated to two significant figures of the value provided in the example.

[0028] For all compounds represented by an empirical chemical formula with multiple letter and number subscripts (such as CH2O), the value of the subscript can be plus or minus 50% of the indicated value, rounded or truncated to two significant figures. For example, if CH2O is shown, then for the formula C (0.8-1.2) H (1.6-2.4) O (0.8-1.2) of the compound. In an improvement, the value of the subscript can be plus or minus 30% of the value shown as rounded or truncated to two significant figures. In yet another improvement, the value of the subscript can be plus or minus 20% of the value rounded or truncated to two significant figures.

[0029] As used herein, the term "and / or" means that all or only one of the elements of the group may be present. For example, "A and / or B" means "only A, or only B, or both A and B". In the case of "only A", the term also covers the possibility that B is absent, that is, "only A, not B".

[0030] It should also be understood that the present invention is not limited to the specific embodiments and methods described below, as the specific components and / or conditions can of course vary. In addition, the terms used herein are for the purpose of describing only the specific embodiments of the present invention and are not intended to be limiting in any way.

[0031] The terms "comprising", "including", "having", "containing", or "characterized by" are synonymous. These terms are inclusive and open-ended and do not exclude additional, unrecited elements or method steps.

[0032] The phrase "consisting of" excludes any element, step, or ingredient not specified in the claim. When this phrase appears in a clause of the body of the claim rather than immediately following the preamble, it limits only the elements set forth in that clause; other elements are not excluded from the overall claim.

[0033] The phrase "consisting essentially of" limits the scope of the claim to the specified materials or steps, plus those materials or steps that do not materially affect one or more of the basic and novel features of the claimed subject matter.

[0034] With respect to the terms "comprising", "consisting of", and "consisting essentially of", where one of these three terms is used herein, the subject matter disclosed and claimed in the present invention may include the use of either of the other two terms.

[0035] The term "one or more" means "at least one", and the term "at least one" means "one or more". The terms "one or more" and "at least one" include "a plurality" as a subset.

[0036] The description of a group or class of materials suitable for a given purpose in connection with one or more embodiments means that a mixture of any two or more members of that group or class is suitable. The description of ingredients in chemical terms refers to the ingredients when added to any combination specified in the specification and does not necessarily exclude chemical interactions between the ingredients of the mixture once mixed. The first definition of an acronym or other abbreviation applies to all subsequent uses of the same abbreviation herein, with necessary modifications to apply to the normal grammatical variations of the originally defined abbreviation. Unless expressly stated to the contrary, measurements of properties are determined by the same technique as that referenced previously or subsequently for the same property.

[0037] The cost of a platinum (Pt) / carbon (C) cathode electrocatalyst can be at least half of the manufacturing price of a commercial proton exchange membrane fuel cell (PEMFC), and its degradation during cycling limits the life of the PEMFC. By using high-surface-area carbon as the substrate, the price can be reduced with a smaller Pt loading while maintaining a high electrochemically active surface area of the Pt catalyst.

[0038] Optimizing the microstructure of the carbon support for Pt catalysts is a promising step for improving the durability of PEMFCs and reducing their cost. The correlation between the surface area of the carbon support and the ECSA of the Pt catalyst deposited on the carbon support can be considered in the optimization step. For example, when the same weight percentage of Pt loading is applied, the larger the surface area of the carbon support, the larger the ECSA of the Pt catalyst deposited on the carbon support. This trend may be due to the uniform small size (e.g., an average diameter of about 3 nm) and uniform distribution of Pt nanoparticles on the carbon support with a relatively high surface area. Although the Pt / C electrocatalyst with high surface area carbon (HSAC) achieves a relatively high ECSA at a lower Pt loading, the Pt / C electrocatalyst with HSAC still suffers from the same or similar severe ECSA degradation as the Pt / C electrocatalyst with low surface area carbon (LSAC) during cycling. One proposal to improve the cycling stability of Pt / C is to replace the oxidizing amorphous carbon with less reactive graphitized carbon.

[0039] One proposal for fabricating graphitic carbon with a very high surface area involves the silver templating method. According to this method, a mesoporous carbon nanodendrite (MCND) structure is synthesized to have primary particles containing bubble-like hollow graphitic carbon nanoparticles (HGCN) that have surface pores. While typical HGCN have wall thicknesses exceeding 5 nm (e.g., more than 10 graphene layers), the MCND structure can have single-layer graphene walls, resulting in a very high surface area (e.g., 1,610 m 2 / g).

[0040] Although the MCND structure has shown promise as a carbon support with a very high surface area, there is still a need to fabricate graphitic carbon nanoparticles with a very high surface area. Additionally, durability can be improved by replacing amorphous carbon with less oxidizing graphitic carbon.

[0041] In one or more embodiments, carbon precursors are disclosed for fabricating graphitic carbon nanoparticles having a single-layer graphite structure (e.g., a graphite shell or wall) with a very high surface area. The single layer can refer to a layer of a two-dimensional material (e.g., graphite). The shell or wall can refer to a single-layer structure that extends in three dimensions. The graphitic carbon nanoparticles can refer to carbon nanoparticles in which one or more graphitic materials (e.g., a crystalline form of carbon atoms in a hexagonal structure) are present. One or more graphitic materials can be formed from one or more graphene materials. In one or more embodiments, the carbon nanoparticles can be entirely graphitic, meaning that 100% of the carbon nanoparticles comprise one or more graphitic materials. The high surface area can be in the range of 500 to 3,000 m 2 / g, and in other embodiments, in the range of 1,400 m 2 / g and above (e.g., 1,400 to 3,000 m2 / g).

[0042] In one or more embodiments, a precursor carbon structure is disclosed that can be fabricated into a single-layer graphite carbon mesostructure having desired characteristics and alleviating the degradation and cost issues of the Pt / C electrocatalyst in PEMFCs. The carbon mesostructure can be a structure within the mesoscale range between the microscale and the macroscale. The mesoscale range can be from nanometers (10 -9 meters) to micrometers (10 -6 meters). The precursor carbon structure can include an amorphous carbon structure. An amorphous carbon structure can refer to a disordered or random arrangement of carbon atoms (e.g., lacking a well-defined crystal structure). The carbon structure can be completely amorphous. The single-layer graphite material can include carbon nanoclusters. A carbon nanostructure can refer to a carbon material having one or more dimensions within the nanoscale range (e.g., in the range of 1 to 100 nanometers). These structures can also be used to synthesize carbon structures for other applications specifying high surface area and good durability, such as anode materials for alkaline ion batteries.

[0043] Figure 1 A schematic side view of certain components of a PEMFC 110 according to one embodiment is shown. As Figure 1 shown, the PEMFC 110 includes an anode catalyst support 112 coated with an anode catalyst layer 114 formed of an anode catalyst material and a cathode catalyst support 16 coated with a cathode catalyst layer 118 formed of a cathode catalyst material. A polymer electrolyte material (PEM) 120 extends between the anode catalyst support 112 and the cathode catalyst support 116. The cathode catalyst material can be dispersed at the interface between the PEM 120 and a current collector (not shown) supported by the cathode catalyst support 118. The current collector can be a porous carbon current collector. The anode catalyst layer 114 is located between the anode catalyst support 112 and the PEM 120. The cathode catalyst layer 118 is located between the cathode catalyst support 116 and the PEM 120. The anode 122 generally can refer to the anode catalyst support 112 and the anode catalyst layer 114. The cathode 124 generally can refer to the cathode catalyst support 116, the cathode catalyst layer 118, and the current collector (not shown). The PEMFC 110 also includes first and second gas diffusion layers (GDLs) (not shown). The first GDL is adjacent to the outer surface 126 of the anode catalyst support 112, and the second GDL is adjacent to the outer surface 128 of the cathode catalyst support 116.

[0044] In one or more embodiments, a precursor carbon structure is disclosed that undergoes graphitization at an elevated temperature (e.g., 3,000 K) to form carbon nanoparticles having single-layer graphite walls. These precursor carbon structures can be confirmed by molecular dynamics simulations of the graphitization of amorphous carbon nanoparticles at elevated temperatures.

[0045] Figure 2A Schematic illustration of the graphitization of amorphous carbon solid spheres 200 into graphite carbon nano-onions 202 by annealing at about 3,000 K. The term nano-onion can refer to nested (e.g., concentric) graphite structures of carbon. Figure 2B Schematic illustration of the graphitization of amorphous carbon hollow spheres 204 into single-layer graphite carbon hollow shells 206 by annealing at about 3,000 K. Graphitization of solid and hollow amorphous carbon nanospheres occurs in a carbon environment comparable to that of amorphous carbon (with a density of 2.97 g / cm 3 , and an average coordination number (CN) of 3.85). As Figure 2A shown, carbon starting as solid spheres results in a graphite but onion-like shape, which may be undesirable as the onion shape reduces the available surface area of the carbon. For example, the inner layers of graphite carbon nano-onions 202 may be inaccessible for certain applications (such as platinum deposition), with an average CN of nearly 3 at about 3,000 K.

[0046] Figure 3A is a plot of the number of carbon atoms per volume of graphite carbon nano-onions vs. the distance from the center showing different initial radii (i.e., about and about ) and an initial density of 2.97 g / cm 3 . When starting with a smaller radius (e.g., about Figure 2A ), the annealed structure consists of a single layer of carbon. Larger radii (e.g., about ) result in a multi-layer graphite structure. As shown, the spacing between the peaks of the curve of the number of carbon atoms per volume vs. the distance from the center of the sphere ranges from about 0.3 to 0.4 nm. This range matches the experimentally measured interlayer distance between graphite layers (0.335 nm). In contrast, as Figure 3A shown, amorphous carbon hollow spheres graphitize into single-walled graphite shells. The characteristic differences between graphite solid spheres and graphite hollow spheres can lead to significant differences in surface area. Figure 2B shown, amorphous carbon hollow spheres graphitize into single-walled graphite shells. The characteristic differences between graphite solid spheres and graphite hollow spheres can lead to significant differences in surface area.

[0047] Figure 3B is a plot of the surface area variation of nano-onion solid spheres and hollow spheres with different initial radii and an initial density of 2.97 g / cm 3 . Figure 3B Supports the generation of carbon precursors for one or more embodiments starting from hollow carbon of any size described (e.g., about to about ). Figure 3B Also supports the generation of carbon precursors for one or more embodiments from non-hollow carbon clusters smaller than a certain radius (e.g., about ). As Figure 3BAs shown, the surface area of the graphite solid sphere decreases inversely with the radius of the amorphous carbon sphere precursor at 3,000 K, while the surface area of the graphite sphere remains unchanged above 1,400 m 2 / g.

[0048] Graphitization of amorphous carbon nanoparticles can also be observed in simulations of two other models with experimentally reported densities and respective average CNs. The first model can use 1.55 g / cm 3 and a CN equal to 2.97. Figure 4A is a graph showing the surface areas of the nano-onion solid and hollow spheres with a density of 1.55 g / cm 3 changing with the initial sphere radius. The second model can use 2.44 g / cm 3 and the CN is equal to 3.33. Figure 4B is a graph showing the surface areas of the nano-onion solid and hollow spheres with a density of 2.44 g / cm 3 changing with the initial sphere radius. For both densities of these models, a similar trend was observed, that is, the hollow spheres have a constant surface area above 1,400 m 2 / g, while the surface area of the nano-onion solid spheres decreases with the increase of the sphere radius. Figure 4A and 4B provide confirmation of the results starting from different initial carbon densities. The above observations on the graphitization of amorphous carbon nanoparticles can be the basis for developing one or more structures of amorphous carbon precursors, which can be annealed to a single-layer graphite structure at 3,000 K. Figure 3B

[0049] In one or more embodiments, the amorphous carbon precursor is a highly defective amorphous carbon nanocluster. The highly defective amorphous carbon nanocluster can have a large number of micropores (e.g., pores with a diameter less than 2 nanometers). A high number of micropores can exist in the range of 0.5 to 2.0 cm 3 / g. For amorphous carbon nanoparticles with a density less than 2.5 g / cm 3 , the percentage of the removed mass of the amorphous carbon nanoparticles can be at least 70%. The percentage of the removed mass can be any of the following percentages or within the range of any two of the following percentages: 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, and 90%. For densities greater than 2.5 g / cm 3 ​The amorphous carbon nanoparticles can have a mass reduction of at least 80%. The percentage of the removed mass can be any of the following percentages or within the range of any two of the following percentages: 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, and 90%. For example, if the mass reduction is 80%, 80% of the atoms can be ejected from the amorphous carbon structure through an ejection step using techniques such as ion bombardment or etching.

[0050] Figure 5 A graph depicting the surface area of graphitized carbon spheres with different mass losses is described. Figure 5 Indicates that a lower initial carbon mass results in a higher surface area and more graphitic carbon mesostructures. As Figure 5 Shown, the greater the percentage of mass loss, the higher the surface area after annealing at 3,000K. In one or more embodiments, for amorphous carbon nanoparticles with a density less than 2.5 g / cm 3 Structural annealing of amorphous carbon nanoparticles with a mass loss exceeding 70% produces a structure with a single graphitic wall and thus results in a high surface area above 1,400 m g / g, comparable to the surface area of graphitic hollow spheres with single walls.

[0051] Figure 6 A schematic diagram of an amorphous carbon sphere 600 with a cylindrical defect 602 is described, which has a mass reduction exceeding 70% and graphitizes into a single-layer graphitic carbon nanocluster 604. In this embodiment, the mesostructured carbon is mostly single-layered and entirely graphitic. Advanced experimental characterization techniques can be used to identify the mesostructured carbon structure. Non-limiting examples include transmission electron microscopy, Raman spectroscopy, and electron energy loss spectroscopy.

[0052] In one or more embodiments, the amorphous carbon precursor is an amorphous carbon nanocluster with an equivalent diameter less than 3 nanometers (e.g., less than 2 nanometers). Figure 7A A schematic diagram of an amorphous carbon sphere 700 graphitized into a single-layer graphitic carbon nanocluster 702 with a radius of approximately 0.8 nanometers is described. Figure 7B A schematic diagram of an amorphous carbon sphere 704 graphitized into a double-layer graphitic carbon nanocluster 706 with a radius of approximately 1.0 nm is described. The amorphous carbon sphere 700 and the amorphous carbon sphere 704 can have a density of 2.44 g / cm at 2,500K to 4,000K (e.g., 3,000K). 3The initial density. In one or more embodiments, at radii below a specific initial size (e.g., a radius less than about 0.9 nanometers), the annealing step predominantly produces monolayer graphite carbon mesostructures. This is observed even in the absence of mass loss. In one or more embodiments, for larger initial radii (e.g., a radius greater than about 0.9 nanometers), the mesostructured carbon is graphite but onion-like.

[0053] As Figure 7B shown, amorphous carbon spheres 704 with a radius of approximately 1.0 nanometers are graphitized into bilayer graphite carbon nanoclusters 706. In one or more embodiments, to obtain single-walled structures, the diameter of the amorphous carbon nanoparticles can be less than 2.0 nm, depending on the initial density. For initial densities of 1.55 g / cm 3 and 2.97 g / cm 3 and amorphous carbon nanoparticles with radii below 1.5 nanometers and 0.8 nanometers, respectively, can be used to obtain carbon nanoclusters with single-walled structures after annealing at 2,500 K to 4,000 K (e.g., 3,000 K). The amorphous carbon nanoclusters can have an amorphous carbon nanocluster density of 1 to 1.6 g / cm 3 . When the amorphous carbon nanoclusters have an amorphous carbon nanocluster density of 1.6 to 2.4 g / cm 3 , the nominal nanocluster diameter can be less than 2 nanometers. When the amorphous carbon nanoclusters have an amorphous carbon nanocluster density of 2.4 to 3.0 g / cm 3 , the nominal nanocluster diameter can be less than 1.6 nanometers. The amorphous carbon nanoclusters can include defects.

[0054] The processes, methods, or algorithms disclosed herein can be transferred to or implemented by a processing device, controller, or computer, which can include any existing programmable electronic control unit or dedicated electronic control unit. Similarly, the processes, methods, or algorithms can be stored in many forms as data and instructions executable by a controller or computer, including but not limited to information permanently stored on non-writable storage media such as ROM devices and information changeably stored on writable storage media such as floppy disks, magnetic tapes, CDs, RAM devices, and other magnetic and optical media. The processes, methods, or algorithms can also be implemented in software-executable objects. Alternatively, appropriate hardware components, such as application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), state machines, controllers, or other hardware components or devices, or combinations of hardware, software, and firmware components, can be used to implement the processes, methods, or algorithms, in whole or in part.

[0055] Although the exemplary embodiments have been described above, it does not mean that these embodiments describe all possible forms encompassed by the claims. The words used in the specification are descriptive rather than restrictive, and it should be understood that various changes can be made without departing from the spirit and scope of the present disclosure. As previously mentioned, the features of various embodiments can be combined to form other embodiments of the invention that may not be explicitly described or shown. Although various embodiments may have been described as providing advantages or being preferred over other embodiments or prior art implementations in one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics may be compromised to achieve the desired overall system attributes, depending on the specific application and implementation. These attributes can include, but are not limited to, cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, repairability, weight, manufacturability, ease of assembly, etc. Thus, to the extent that one or more features are described in any embodiment as being less desirable than other embodiments or prior art implementations, these embodiments are not outside the scope of the present disclosure and may be desirable for a particular application.

Claims

1. A carbon precursor for manufacturing a carbon support having a graphite structure, the carbon graphite structure precursor comprising: Defective amorphous carbon spheres having a certain mass loss percentage compared to defect-free amorphous carbon spheres, the defective amorphous carbon spheres being capable of manufacturing a single-layer graphite structure for use as a carbon support.

2. The carbon graphite structure precursor according to claim 1, wherein the density of the defect-free amorphous carbon spheres is less than 2.5 g / cm 3 , and the mass loss percentage is greater than 70%.

3. The carbon graphite structure precursor according to claim 1, wherein the density of the defect-free amorphous carbon spheres is greater than 2.5 g / cm 3 , and the mass loss percentage is greater than 80%.

4. The carbon graphite structure precursor according to claim 1, wherein the defective amorphous carbon spheres include defects.

5. The carbon graphite structure precursor according to claim 4, wherein the defects are cylindrical defects.

6. The carbon graphite structure precursor according to claim 1, wherein the defective amorphous carbon spheres are defective amorphous carbon nanospheres.

7. The carbon graphite structure precursor according to claim 1, wherein the defect-free amorphous carbon spheres include hollow spheres.

8. The carbon graphite structure precursor according to claim 1, wherein the defective amorphous carbon spheres comprise micropores with a diameter of less than 2 nanometers in the range of 0.5 to 2.0 cm 3 / g.

9. A carbon precursor for manufacturing a carbon support having a graphite structure, the carbon graphite structure precursor comprising: Amorphous carbon nanoclusters having a nominal nanocluster diameter of less than 3 nanometers, the amorphous carbon nanoclusters being capable of manufacturing a single-layer graphite structure for use as a carbon support.

10. The carbon graphite structure precursor according to claim 9, wherein the amorphous carbon nanoclusters have an amorphous carbon nanocluster density of 1 to 1.6 g / cm 3 3 11. The carbon graphite structure precursor according to claim 9, wherein the amorphous carbon nanoclusters have an amorphous carbon nanocluster density of 1.6 to 2.4 g / cm 3 , and the nominal nanocluster diameter is less than 2 nanometers.

12. The carbon graphite structure precursor according to claim 9, wherein the amorphous carbon nanoclusters have an amorphous carbon nanocluster density of 2.4 to 3.0 g / cm 3 and the nominal nanocluster diameter is less than 1.6 nanometers.

13. The carbon graphite structure precursor according to claim 9, wherein the amorphous carbon nanoclusters include defects.

14. A method for manufacturing a single-layer graphite structure for use as a carbon support, the method comprising: Annealing amorphous carbon spheres to form a single-layer graphite structure; And Shaping the single-layer graphite structure into the carbon support.

15. The method according to claim 14, wherein the amorphous carbon spheres are defective amorphous carbon spheres, and further comprising forming the defective amorphous carbon spheres from starting amorphous carbon spheres.

16. The method according to claim 15, wherein the forming step comprises reducing the mass of the starting carbon spheres by a certain mass loss percentage to obtain the defective amorphous carbon spheres.

17. The method according to claim 16, wherein the forming step comprises ion-bombarding the starting carbon spheres.

18. The method according to claim 16, wherein the forming step comprises etching the starting carbon spheres.

19. The method according to claim 14, wherein the single-layer graphite structure is a single-layer graphite shell.

20. The method according to claim 14, wherein the carbon support is configured to support an electrocatalyst.

Images