Near-infrared reflective copper-coated particles

Abstract

To provide a dark color pigment that absorbs electromagnetic radiation within a visible spectrum and reflects near IR electromagnetic radiation.SOLUTION: A copper oxide coated pigment includes a particle having an external surface and a copper oxide layer on the external surface. The pigment has a reflectance of 5% or less with regard to electromagnetic radiation within a visible spectrum and a reflectance of 5% or more with regard to electromagnetic radiation of near IR and within a LiDAR spectrum. The particle is of a cobalt oxide or carbon black. A manufacturing method of a copper oxide coated particle includes: combining a deposition agent and a solution of a copper nitrate and a particle to form a coated particle, in which the particle is a cobalt oxide or carbon black; washing the particle to obtain a washed coated particle; filtering the washed coated particle to obtain a filtered coated particle; drying the filtered coated particle to obtain a dried coated particle; and sintering the dried coated particle to form a copper oxide coated particle.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] This specification relates generally to particles that reflect near-infrared (near-IR) electromagnetic radiation, and more particularly to copper oxide coated particles that reflect near-IR electromagnetic radiation. [Background technology]

[0002] LiDAR systems using pulsed laser electromagnetic radiation having wavelengths of 905 nanometers (nm) or 1050 nm have been proposed and tested as obstacle detection and avoidance systems for autonomous vehicles. However, the dark (e.g., black) pigments used in paint systems to provide a dark color not only absorb visible electromagnetic radiation, which darkens the color, but also near-IR electromagnetic radiation, which has a wavelength greater than about 750 nanometers, including LiDAR electromagnetic radiation. Summary of the Invention [Problem to be solved by the invention]

[0003] Therefore, there is a need for alternative dark pigments that absorb electromagnetic radiation in the visible spectrum but reflect near-IR electromagnetic radiation having wavelengths of about 905 nm or 1050 nm. [Means for solving the problem]

[0004] A first aspect is a copper oxide-coated pigment comprising a particle having an outer surface and a layer of copper oxide on the outer surface of the particle, wherein the copper oxide-coated pigment has a reflectance of 5% or less for electromagnetic radiation in the visible spectrum, and the copper oxide-coated pigment has a reflectance of 5% or more for electromagnetic radiation in the near-IR and LiDAR spectrum, and the particle comprises a copper oxide-coated pigment selected from cobalt oxide (Co3O4) or carbon black.

[0005] A second embodiment includes the copper oxide coated pigment of the first embodiment, wherein the particles are cobalt oxide (Co3O4).

[0006] A third embodiment comprises the copper oxide coated pigment of the first embodiment, wherein the particles are carbon black.

[0007] A fourth embodiment comprises the copper oxide-coated pigment of any one of the first to third embodiments, wherein the copper oxide-coated pigment has a reflectance for electromagnetic radiation in the visible spectrum that is 2% or less.

[0008] A fifth embodiment comprises the copper oxide-coated pigment of any one of the first through fourth embodiments, wherein the copper oxide-coated pigment has a reflectance for electromagnetic radiation in the near-IR and LiDAR spectrum that is 20% or greater.

[0009] A sixth embodiment comprises the copper oxide-coated pigment of any one of the first to fifth embodiments, wherein the copper oxide-coated pigment has a reflectance for electromagnetic radiation in the visible spectrum of equal to or greater than 0.5% and equal to or less than 2%.

[0010] A seventh embodiment comprises the copper oxide-coated pigment of any one of the first to sixth embodiments, wherein the copper oxide-coated pigment has a reflectance for electromagnetic radiation in the near-IR and LiDAR spectrum that is equal to or greater than 10% and equal to or less than 65%.

[0011] An eighth aspect comprises the copper oxide-coated pigment of any one of the first to seventh aspects, wherein the copper oxide-coated pigment has a blackness of 150 or greater and 165 or less.

[0012] A ninth embodiment includes a paint comprising a paint binder and at least one copper oxide-coated pigment according to any one of the first to eighth embodiments.

[0013] A tenth embodiment includes the paint of the ninth embodiment, wherein the paint has a color with a value of 40 or less in the CIELAB color space.

[0014] An eleventh aspect includes a vehicle having a body panel painted with the paint of the ninth or tenth aspect.

[0015] A twelfth embodiment includes a method of forming copper oxide coated particles, the method including combining a precipitating agent with a solution including copper nitrate and particles, thereby forming coated particles, where the particles are cobalt oxide (Co3O4) or carbon black; washing the particles, thereby obtaining washed coated particles; filtering the washed coated particles, thereby obtaining filtered coated particles; drying the filtered coated particles, thereby obtaining dried coated particles; and calcining the dried coated particles to form the copper oxide coated particles.

[0016] A thirteenth embodiment includes the method of the twelfth embodiment, wherein the precipitating agent is selected from the group consisting of sodium hydroxide, sodium carbonate, and ammonium carbonate.

[0017] A fourteenth embodiment includes the method of the twelfth or thirteenth embodiment, wherein the precipitating agent is ammonium carbonate.

[0018] A fifteenth embodiment includes the method of any one of the twelfth to fourteenth embodiments, wherein the particles are cobalt oxide (Co3O4).

[0019] A sixteenth aspect includes the method of any one of the twelfth to fifteenth aspects, wherein the particles are carbon black particles.

[0020] A seventeenth aspect includes the method of any one of the twelfth to sixteenth aspects, wherein the coated particles include copper nitrate coated particles, copper hydroxide coated particles, or copper carbonate coated particles.

[0021] An eighteenth embodiment includes the method of any one of the twelfth to seventeenth embodiments, wherein washing the coated particles includes washing the coated particles in a mixture of ethanol and water.

[0022] A nineteenth embodiment includes the method of the fifteenth embodiment, wherein drying the filtered coated particles comprises drying the filtered coated particles at a temperature of at least 100°C and not more than 140°C for a time of at least 0.5 hours and not more than 5.0 hours.

[0023] A twentieth embodiment includes the method of the nineteenth embodiment, wherein calcining the dried coated particles comprises calcining the dried coated particles at a temperature of at least 430°C and at most 470°C for a time of at least 0.5 hours and at most 5.0 hours.

[0024] A twenty-first embodiment includes the method of the sixteenth embodiment, wherein drying the filtered coated particles comprises drying the filtered coated particles at a temperature of at least 100°C and not more than 140°C for a time period of at least 5 hours and not more than 15 hours.

[0025] A twenty-second embodiment includes the method of the twenty-first embodiment, wherein calcining the dried coated particles includes calcining at a temperature of at least 200°C and at most 300°C for at least 0.5 hours and at most 5.0 hours.

[0026] A twenty-third embodiment includes a method of forming copper oxide-coated cobalt oxide particles, the method including combining a sodium carbonate precipitating agent with a solution including copper nitrate and cobalt nitrate, thereby forming the coated cobalt oxide particles; washing the coated cobalt oxide particles, thereby obtaining washed coated cobalt oxide particles; filtering the washed coated cobalt oxide particles, thereby obtaining filtered coated cobalt oxide particles; drying the filtered coated cobalt oxide particles, thereby obtaining dried coated cobalt oxide particles; and calcining the dried coated cobalt oxide particles to form the copper oxide-coated cobalt oxide particles.

[0027] A twenty-fourth embodiment includes the method of the twenty-third embodiment, wherein the coated cobalt oxide particles comprise copper nitrate-coated cobalt oxide.

[0028] A twenty-fifth embodiment includes the method of the twenty-third or twenty-fourth embodiment, wherein drying the filtered coated cobalt oxide particles includes drying the filtered coated cobalt oxide particles at a temperature of at least 100°C and not more than 140°C for a time of at least 0.5 hours and not more than 5.0 hours.

[0029] A 26th embodiment includes the method of any one of the 23rd to 25th embodiments, wherein calcining the dried coated cobalt oxide particles includes calcining the dried coated cobalt oxide particles at a temperature of at least 430°C and not more than 470°C for a time period of at least 0.5 hours and not more than 5.0 hours.

[0030] These and additional features provided by the embodiments described herein will be more fully understood by reference to the following detailed description taken in conjunction with the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The embodiments set forth in the drawings are illustrative and representative in nature and are not intended to limit the subject matter defined by the claims. The following detailed description of exemplary embodiments can be understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which: [Brief explanation of the drawings]

[0032] [Figure 1A] FIG. 1A is a graph of reflectance versus wavelength for electromagnetic radiation for conventional colorants.

[0033] [Figure 1B] FIG. 1B is a graphical representation of reflectance versus wavelength for electromagnetic radiation for a colorant according to embodiments disclosed and described herein.

[0034] [Figure 2] FIG. 2 is a bar graph showing the blackness of commercial materials and black TiO2.

[0035] [Figure 3] FIG. 3 shows a schematic diagram of a system including copper oxide coated cobalt oxide particles according to embodiments disclosed and described herein.

[0036] [Figure 4A] FIG. 4A is a bar graph showing the blackness of various materials including copper oxide coated cobalt oxide before application of a clear coat according to embodiments disclosed and described herein.

[0037] [Figure 4B] FIG. 4B is a bar graph showing the blackness of various materials including copper oxide coated carbon black after application of a clear coat according to embodiments disclosed and described herein.

[0038] [Figure 5] FIG. 5 is an image taken with an IR detection camera showing the reflection of electromagnetic radiation in the near IR and LiDAR spectrum of copper oxide coated cobalt oxide according to embodiments disclosed and described herein.

[0039] [Figure 6] FIG. 6 illustrates a schematic of a vehicle having side panels painted with LiDAR reflective dark paint according to one or more embodiments disclosed and described herein.

[0040] [Figure 7] FIG. 7 is a schematic cross-sectional view of the side panel in FIG. 5 painted with the LiDAR reflective dark paint.

[0041] [Figure 8] FIG. 8 is a bar graph showing the blackness of panels with various pigments before the application of the clear coat.

[0042] [Figure 9] FIG. 9 is a bar graph showing the blackness of panels with various pigments after a clear coat is applied.

[0043] [Figure 10] FIG. 10 is a line graph showing the reflectance of panels with various pigments after a clear coat is applied.

[0044] [Figure 11] FIG. 11 is a bar graph showing the LiDAR intensity of panels with various pigments after a clear coat was applied.

[0045] [Figure 12A] FIG. 12A is an SEM image showing copper oxide coated carbon black according to embodiments disclosed and described herein. [Figure 12B] FIG. 12B is an SEM image showing copper oxide coated carbon black according to embodiments disclosed and described herein. [Figure 12C] FIG. 12C is an SEM image showing copper oxide coated carbon black according to embodiments disclosed and described herein.

[0046] [Figure 13] FIG. 13 is a bar graph showing the LiDAR intensity of panels with various pigments after a clear coat was applied. DETAILED DESCRIPTION OF THE INVENTION

[0047] According to one or more embodiments described herein, the copper oxide-coated cobalt oxide pigment includes cobalt oxide particles having an outer surface and a layer of copper oxide on the outer surface of the cobalt oxide particles, wherein the copper oxide-coated cobalt oxide pigment has a reflectance of 5% or less for electromagnetic radiation in the visible spectrum, and the copper oxide-coated cobalt oxide pigment has a reflectance of 5% or more for electromagnetic radiation in the near-IR and LiDAR spectrum.

[0048] According to one or more embodiments described herein, a copper oxide-coated carbon black pigment includes carbon black particles having an outer surface and a layer of copper oxide on the outer surface of the carbon black particles, wherein the copper oxide-coated carbon pigment has a reflectance of 5% or less for electromagnetic radiation in the visible spectrum, and the copper oxide-coated carbon black pigment has a reflectance of 5% or more for electromagnetic radiation in the near-IR and LiDAR spectrum.

[0049] Thus, the copper oxide-coated particles disclosed and described herein exhibit a dark color and reflect near-IR electromagnetic radiation (including LiDAR) having wavelengths between and including 850 nm and 1550 nm. In embodiments, the copper oxide-coated particles disclosed and described herein can be included in a paint system to form a near-IR and LiDAR-reflective dark paint that can be used in any application where traditional paints are used. For example, the paint systems disclosed and described herein can be used to coat portions of vehicles, buildings, roads, traffic markers, or any other object so that near-IR and LiDAR detection systems can detect the article coated with the near-IR and LiDAR-reflective dark paint. In embodiments, the copper oxide-coated particles disclosed and described herein can be used in black paint, or the copper oxide-coated particles can be used with other pigments or colorants in paints of any color.

[0050] As used herein, the term "near-IR electromagnetic radiation" refers to electromagnetic radiation having wavelengths between and including 750 nm and 950 nm, and "LiDAR" refers to electromagnetic radiation having wavelengths between and including 905 nm and 1550 nm.

[0051] As used herein, the term "visible spectrum" refers to electromagnetic radiation having wavelengths between and including 350 nm and 750 nm.

[0052] The LiDAR reflective paint may be disposed on a surface to provide a LiDAR-reflective colored surface. The surface color may be black, but may also be any other color by incorporating the copper oxide-coated particles disclosed and described herein along with other pigments and colorants. Non-limiting examples of applications of the paint disclosed and described herein include surfaces such as vehicle body panels, e.g., vehicle door panels, vehicle quarter panels, architectural surfaces, road surfaces, traffic sign surfaces, and other surfaces where near-IR or LiDAR reflection is desired. The use of LiDAR-reflective copper oxide-coated particles allows vehicles, even dark-colored vehicles, or other surfaces to be detected by LiDAR systems. Various embodiments of the LiDAR-reflective copper oxide-coated particles and methods of making and using the same are described in further detail herein with specific reference to the accompanying drawings.

[0053] One difficulty in forming dark (e.g., black) particles that reflect LiDAR or near-IR electromagnetic radiation and coating systems containing dark particles is the proximity of the visible spectrum of electromagnetic radiation to near-IR electromagnetic radiation or LiDAR. Materials that provide dark colors, such as black, do not reflect electromagnetic radiation within the visible spectrum of electromagnetic radiation. Such materials generally also do not reflect electromagnetic radiation just outside the visible spectrum of electromagnetic radiation, such as near-IR and LiDAR. Carbon black is one such material commonly used as a dark pigment, and it does not reflect electromagnetic radiation within the visible spectrum, nor does it reflect near-IR or LiDAR electromagnetic radiation. Therefore, a material that does not reflect electromagnetic radiation within the visible spectrum but reflects near-IR or LiDAR electromagnetic radiation is required to have a very sharp increase in reflectance just outside the visible spectrum of electromagnetic radiation.

[0054] Referring now to FIG. 1A, the reflectance of materials commonly used as colorants in paint systems is shown. The reflectance percentage is represented along the y-axis of FIG. 1A, and the wavelength of electromagnetic radiation is given along the x-axis of FIG. 1A. The reflectance of a conventional black colorant, such as carbon black, is shown along the bottom of the graph. As shown in FIG. 1A, the carbon black colorant does not reflect electromagnetic radiation within the visible spectrum (left side of the graph). As shown in FIG. 1A, the reflectance of this black colorant is approximately zero percent within the visible spectrum of electromagnetic radiation. This indicates that this colorant provides a dark, nearly pure black color. However, this conventional colorant reflects approximately zero percent of electromagnetic radiation outside the visible spectrum (right side of the graph), such as near-IR electromagnetic radiation or LiDAR electromagnetic radiation (e.g., from above about 750 nanometers (nm) to about 1550 nm). Similarly, near the top of the graph, the reflectance of white TiO, a conventional white colorant, is shown. As shown in FIG. 1A, white TiO2 reflects near-IR and LiDAR electromagnetic radiation at greater than 40% at 1550 nm and approximately 60% at 905 nm, as shown on the right side of the graph (e.g., from approximately above 750 nm to 1550 nm). However, as its name suggests, white TiO2 also reflects electromagnetic radiation within the visible spectrum. As shown in FIG. 1A, white TiO2 reflects nearly 80% of electromagnetic radiation within the visible spectrum. Therefore, neither of these colorants—carbon black or white TiO2—is suitable as a dark particle that also reflects near-IR or LiDAR electromagnetic radiation.

[0055] FIG. 1B is a graph illustrating the target condition for particles that do not reflect light in the visible spectrum of electromagnetic radiation but reflect near-IR and LiDAR electromagnetic radiation. In FIG. 1B, the percentage of reflectance is represented along the y-axis, and the wavelength of electromagnetic radiation is given along the x-axis. Along the bottom of the graph, the reflectance of a conventional black colorant is shown, which is the same as the reflectance of a conventional black colorant (such as carbon black) shown in FIG. 1A. As shown in FIG. 1B, particles that do not reflect electromagnetic radiation in the visible spectrum and reflect near-IR and LiDAR electromagnetic radiation have at least two distinct reflectance regions. The first reflectance region is in the visible spectrum of electromagnetic radiation, indicated as "1" on the left side of the graph in FIG. 1B. In this reflectance region, particles that do not reflect electromagnetic radiation in the visible spectrum and reflect near-IR and LiDAR electromagnetic radiation behave the same as conventional black colorants (such as carbon black) by not reflecting electromagnetic radiation in the visible spectrum. As shown in FIG. 1B, particles that do not reflect electromagnetic radiation in the visible spectrum and that reflect near-IR and LiDAR electromagnetic radiation reflect approximately zero percent of electromagnetic radiation in the visible spectrum, but these particles have a second region of reflection that is outside the visible spectrum of electromagnetic radiation.

[0056] The second reflective region encompasses electromagnetic radiation with wavelengths between and including 750 nm and 1050 nm (including near-IR and LiDAR electromagnetic radiation). In the second reflective region, particles that do not reflect electromagnetic radiation within the visible spectrum but reflect near-IR and LiDAR electromagnetic radiation behave similarly to white TiO by reflecting a large amount of electromagnetic radiation within the second reflective region. As shown in FIG. 1B, particles that do not reflect electromagnetic radiation within the visible spectrum but reflect near-IR and LiDAR electromagnetic radiation, for example, reflect approximately 60% of LiDAR electromagnetic radiation having a wavelength of 905 nm and more than 40% of LiDAR electromagnetic radiation having a wavelength of 1550 nm. By having a reflectivity in the second reflective region similar to white TiO, the particles can reflect a sufficient amount of near-IR and LiDAR electromagnetic radiation so that the particles can be detected by a LiDAR system.

[0057] FIG. 1B illustrates the difficulty of creating particles that do not reflect electromagnetic radiation in the visible spectrum and that reflect near-IR and LiDAR electromagnetic radiation. In particular, FIG. 1B shows a sharp increase in reflectance just outside the visible spectrum of electromagnetic radiation. In embodiments, this sharp increase in reflectance occurs at or about 905 nm, a wavelength of electromagnetic radiation commonly used in LiDAR systems. As shown in FIG. 1B, reflectance increases from about 0 percent to about 60 percent at about 905 nm. Creating particles that exhibit such a clear and sharp increase in reflectance is challenging and leaves little room for error. For example, if a material reflects excessive amounts of electromagnetic radiation in the visible spectrum, it will not appear pure black, but rather have a slight tint of red or purple, for example. However, if a material does not reflect a sufficient amount of near-IR or LiDAR electromagnetic radiation, the material will be unsuitable for detection by a LiDAR system.

[0058] Some materials do not reflect electromagnetic radiation within most of the visible spectrum and reflect near-IR and LiDAR electromagnetic radiation, but these materials have not been able to reproduce the visual appearance of carbon black (i.e., having approximately 0% reflectance for electromagnetic radiation within the visible spectrum). One such material that has attracted interest is iron chromium oxide and its derivatives. Iron chromium oxide materials are generally capable of reflecting near-IR and LiDAR electromagnetic radiation, but colorants made from iron chromium oxide materials have a slight red or blue color and are therefore commonly referred to as "cool black." Figure 2 is a bar graph showing the blackness of various materials on the y-axis. The blackness was measured using an X-Rite spectrophotometer. The leftmost image in Figure 2 is carbon black, a material commonly used as a black colorant, but which does not reflect near-IR or LiDAR electromagnetic radiation. As shown in Figure 2, carbon black has a blackness of approximately 165. Materials 1-7 are iron oxide chromium-containing materials that reflect near-IR or LiDAR electromagnetic radiation, but as can be seen in Figure 2, these materials have a blackness of approximately 142 or less. This difference in blackness is significant because Materials 1-7 have a red or blue tint. This significant gap in blackness between carbon black and Materials 1-7 indicates that Materials 1-7 are generally not suitable for use in applications where a pure black color is desired, such as paints in general and automotive paints.

[0059] Another material of interest for black applications is copper(II) oxide, or cupric oxide (CuO). CuO is a common inorganic compound that is a black solid material in its natural state. However, not all copper oxides have this black color. Another stable oxide of copper is cuprous oxide (CuO), which is a red solid in its natural state. Therefore, the oxidation state of copper is important to ensure a material has a black color. CuO is a product of the copper mining industry and a precursor to many other copper-containing products and chemical compounds. CuO has been used as a black pigment in certain applications, such as ceramics and glazes. However, CuO does not reflect near-IR or LiDAR electromagnetic radiation. That is, in its natural state, CuO behaves much like carbon black in that it does not reflect electromagnetic radiation in the visible spectrum, nor does it reflect electromagnetic radiation in the near-IR or LiDAR spectrum. Without being bound by any particular theory, CuO has a bandgap of 2.0 eV, which does not readily reflect electromagnetic radiation in the near-IR or LiDAR spectrum, as explained in more detail below. If CuO is engineered to have a bandgap that is more suited to reflecting electromagnetic radiation in the near-IR or LiDAR spectrum, the color of the CuO deteriorates to a brownish-black color, which is unsuitable for certain applications, such as paints in general and automotive paints in particular.

[0060] The term "band gap" generally refers to the energy difference (measured in electron volts or eV) between the top of the valence band (VB) and the bottom of the conduction band (CB). The VB is the band of electron orbitals from which electrons can jump and move to the CB when excited. The VB is the outermost electron orbital of an atom that an electron can actually occupy. The band gap is the energy required for an electron to move from the VB to the CB and can be used to measure the electrical conductivity of a material. In optics, the band gap correlates with the threshold at which a material can absorb photons. Therefore, the band gap determines which portion of the electromagnetic spectrum a material can absorb. Generally, materials with larger band gaps absorb more of the short-wavelength portion of the electromagnetic spectrum, while materials with smaller band gaps absorb more of the long-wavelength portion of the electromagnetic spectrum. In other words, a larger band gap means that more energy is required to excite valence electrons to the CB. On the other hand, when the valence band and conduction band overlap, as in metals, electrons can easily move between the two bands, which means the material is highly conductive. However, it has been found that by manipulating the band gap of a material, it is possible to control the types of electromagnetic radiation in the spectrum that the material absorbs.

[0061] Generally, a bandgap of 1.5 eV to 1.8 eV is required for a compound to absorb (i.e., not reflect) electromagnetic radiation in the visible spectrum and reflect electromagnetic radiation in the near-IR and LiDAR spectrum. Without engineering, bulk CuO does not meet these requirements. The reported bandgap of bulk CuO is 2.0 eV, with a blackness of 120. This bandgap lies outside the 1.5 eV to 1.8 eV range believed to reflect electromagnetic radiation in the near-IR and LiDAR spectrum. Furthermore, as discussed above with reference to FIG. 2, a blackness of 120 is significantly lower than the blackness of carbon black, which is 170. Therefore, in the embodiments disclosed and described herein, CuO is engineered by decreasing the particle size of CuO to decrease the bandgap and increase the blackness of CuO.

[0062] As noted above, bulk CuO absorbs (i.e., does not reflect) electromagnetic radiation in the visible spectrum, as indicated by its bandgap of approximately 2.0 eV, and is not suitable as a colorant for reflecting electromagnetic radiation in the near-IR or LiDAR spectrum. However, according to embodiments disclosed and described herein, reducing the size of the CuO particles reduces the bandgap and increases the blackness of the CuO particles. According to embodiments, the bulk CuO particles are reduced to nanoscale particles (also referred to herein as "nanoparticles"). This size reduction of the bulk CuO particles can be achieved by any suitable method, such as, for example, milling, ball milling, jet milling, etc. In embodiments, the bulk CuO particles are reduced to have a crystal size that is 100 nm or less, e.g., 95 nm or less, 90 nm or less, 85 nm or less, 80 nm or less, 75 nm or less, 70 nm or less, 65 nm or less, 60 nm or less, 55 nm or less, 50 nm or less, 45 nm or less, 40 nm or less, 35 nm or less, 30 nm or less, 25 nm or less, 20 nm or less, 15 nm or less, or 10 nm or less.

[0063] In embodiments, the bulk CuO particles have a size of 10 nm to 60 nm, e.g., 10 nm to 55 nm, 10 nm to 50 nm, 10 nm to 45 nm, 10 nm to 40 nm, 10 nm to 35 nm, 10 nm to 30 nm, 10 nm to 25 nm, 10 nm to 20 nm, 10 nm to 15 nm, 15 nm to 60 nm, 15 nm to 55 nm, 15 nm to 50 nm. 55 20nm or more below nm, 20nm or more below 50nm, 20nm or more below 45nm, 20nm or more below 40nm, 20nm or more below 35nm, 20nm or more below 30nm, 20nm or more below 25nm, 60nm or less 25 nm or more, 55 nm or more 25 nm or more, 50 nm or less 25 nm or more, 45 nm or more 25 nm or more, 40 nm or more 25 nm or more, 35 nm or more 25 nm or more, 30 nm or less 25 nm or more, 60 nm or more 30 nm 55 nm or more, 30 nm or more, 50 nm or more, 30 nm or more, 45 nm or more, 30 nm or more, 40 nm or more, 35 nm or more, 35 nm or more, 60 nm or more, 35 nm or more, 55 nm or more, 5 The bulk CuO particles reduced to nanoparticles are referred to herein as "CuO nanoparticles."

[0064] By reducing the size of bulk CuO particles, for example, to the average particle sizes disclosed herein, the band gap of CuO is reduced. In embodiments, the band gap of CuO nanoparticles measured by X-ray photoelectron spectroscopy (XPS) is 1.6 eV to 1.9 eV, e.g., 1.6 eV to 1.8 eV, 1.6 eV to 1.7 eV, 1.7 eV to 1.9 eV, 1.7 eV to 1.8 eV, 1.7 eV to 1.9 eV, 1.7 eV to 1.8 eV, 1.7 eV to 1.8 eV, 1.8 eV to 1.9 eV, etc. Without being bound by theory, it is believed that surface defects resulting from the reduction of bulk CuO to CuO nanoparticles reduce the band gap of the CuO nanoparticles compared to the band gap of the bulk CuO particles. Furthermore, it is believed that the smaller the average crystallite size of the CuO nanoparticles, the smaller the band gap of the CuO nanoparticles. Thus, by reducing bulk CuO particles to CuO nanoparticles according to the embodiments disclosed and described herein, the band gap of the CuO nanoparticles falls within a range that reflects electromagnetic radiation in the near-IR and LiDAR spectrum, such as having a band gap between 1.5 eV and 2.0 eV or between 1.5 eV and 1.8 eV.

[0065] Blackness (i.e., a measure of blackness) also increases as the size of the bulk CuO decreases. Thus, in embodiments, the blackness of the CuO nanoparticles is 130 to 145, e.g., 133 to 145, 135 to 145, 138 to 145, 140 to 145, 143 to 145, 130 to 143, 133 to 143, 135 to 143, 138 to 143, 140 to 143, 130 to 140, 133 to 140, 135 to 140, 138 to 140, 130 to 138, 133 to 138, 135 to 138, 130 to 135, 133 to 135, or 130 to 133. Although the blackness can be increased by reducing the particle size of bulk CuO, the blackness of CuO nanoparticles is less than desired for certain applications such as paints in general and automotive paints in particular.

[0066] According to embodiments disclosed and described herein, the low blackness of CuO nanoparticles (compared to the blackness of carbon black, which is 170) is addressed by depositing a CuO layer on the surface of the particles, which have a blackness greater than that of the CuO nanoparticles. According to embodiments, CuO is deposited on carbon black or cobalt oxide (Co3O4) particles to improve the blackness. As disclosed above, carbon black has a very high blackness. Co3O4 particles are also known to have a high blackness, for example, greater than that of CuO nanoparticles.

[0067] The effect of a system having a CuO layer coated on carbon black or Co3O4 particles is described with reference to FIG. 3. Copper oxide-coated particle system 300 comprises copper oxide-coated particles 310, including carbon black or Co3O4 particles 311 coated with a CuO layer 312. As shown in FIG. 3, according to an embodiment, CuO 312 is deposited on the outer surface of larger carbon black or Co3O4 particles 311 having a particle size of 1 μm or greater and 10 μm or less. As shown in FIG. 3, copper oxide-coated particles 310 may be suspended in a transparent carrier 330, which is not limited and can be any suitable carrier depending on the desired application. Carrier 330 is described in more detail below. Electromagnetic radiation in both the visible spectrum 340 and the near-IR and LiDAR spectrum 350 incident on copper oxide-coated particle system 300 enters copper oxide-coated particle system 300, passes through transparent carrier 330, and impinges on copper oxide-coated particles 310. A portion of the electromagnetic radiation in the visible spectrum 340 is absorbed by the copper oxide 312, and a portion of the electromagnetic radiation in the visible spectrum 340 is transmitted by the copper oxide 312 and incident on the carbon black or cobalt oxide particles 311. The portion of the electromagnetic radiation in the visible spectrum 340 that is incident on the carbon black or cobalt oxide particles 311 is absorbed by the carbon black or cobalt oxide particles 311, and very little electromagnetic radiation in the visible spectrum 340 is reflected out of the copper oxide coated particle system 300.

[0068] Electromagnetic radiation in the near-IR and LiDAR spectrum 350 incident on the copper oxide coated particles 310 is reflected by the copper oxide 312, with a majority of the electromagnetic radiation in the near-IR and LiDAR spectrum 350 being reflected out of the copper oxide coated particle system 300. Electromagnetic radiation in the near-IR and LiDAR spectrum 350 not reflected by the copper oxide 312 is absorbed by the carbon black or cobalt oxide particles 311.

[0069] An inverse correlation exists between the amount of copper oxide 312 on the copper oxide-coated particle 310 and the blackness of the copper oxide-coated particle 310. In other words, the less copper oxide 312 there is in the copper oxide-coated particle 310, the higher the blackness. However, there is a direct relationship between the amount of copper oxide 312 in the copper oxide-coated particle 310 and the reflectivity for electromagnetic radiation in the near-IR and LiDAR spectrum. In other words, the greater the amount of copper oxide 312 in the copper oxide-coated particle 310, the more electromagnetic radiation in the near-IR and LiDAR spectrum is reflected. Thus, embodiments of the copper oxide-coated particle 310 strike a balance between the amount of copper oxide 312 and the amount of carbon black or cobalt oxide 311.

[0070] In an embodiment, the copper oxide-coated particles 310 can contain copper oxide 312 in an amount of 1.0 mass% or more and 90.0 mass% or less, for example, 10.0 mass% or more and 90.0 mass% or less, 20.0 mass% or more and 90.0 mass% or less, 30.0 mass% or more and 90.0 mass% or less, 40.0 mass% or more and 90.0 mass% or less, 50.0 mass% or more and 90.0 mass% or less, 60.0 mass% or more and 90.0 mass% or less, 70.0 mass% or more and 90.0 mass% or less, 80.0 mass% or more and 90.0 mass% or less, 1.0 mass% or more and 80.0 mass% or less, 10.0 mass% or more and 80.0 mass% or less, 20.0 mass% or more and 80.0 mass% or less, 30.0 mass% or more and 80.0 mass% or less, 40.0 mass% or more and 80.0 mass% or less, 50.0 mass% or more and 80.0 mass% or less, 60.0 mass% or more and 80.0 mass% or less, 70.0 mass% or more and 80.0 mass% or less, 25.0 mass% or more and 75.0 mass% or less, 1.0 mass% or more and 70.0 mass% or less, 1.0 mass% or more and 70.0 mass%, 10.0 mass% or more and 70.0 mass% or less, 20.0 mass% or more and 70.0 mass% or less, 30.0 mass% or more and 70.0 mass% or less, 40.0 mass% or more and 70.0 mass% or less, 50.0 mass% or more and 70.0 mass% or less, 60.0 mass% or more and 70.0 mass% or less, 1.0 mass% or more and 60.0 mass% or less, 10.0 mass% or more and 60.0 mass% or less, 20.0 mass% or more and 60.0 mass% or less, 30.0 mass% or more and 60.0 mass% or less, 40.0 mass% or more and 60.0 mass% or less, 50.0 mass% or more and 60.0 mass% or less, 1.0 mass% or more and 50.0 mass% or less, 10.0 mass% or more and 50.0 mass% or less, 20.0 mass% or more and 50.0 mass% or less, 30.0 mass% or more and 50.0 mass% or less, 40.0 mass% or more and 50.0 mass% or less, 1.0 mass% or more and 40.0 mass% or less, 10.0 mass% or more and 40.0 mass% or less, 20.0 mass% or more and 40.0 mass% or less, 30.0 mass% or more and 40.0 mass% or less, 1.0 mass% or more and 30.0 mass% or less, 10.0 mass% or more and 30.0 mass% or less, 20.0 mass% or more and 30.0 mass% or less, 1.0 mass% or more and 20.0 mass% or less, 10.0 mass% or more and 20.0 mass% or less, or 1.0 mass% or more and 10.0 mass% or less, based on the total mass of the copper oxide-coated particles 310.

[0071] In an embodiment, the copper oxide-coated particles 310 can contain carbon black or cobalt oxide 311 in an amount such as 10.0 mass% or more and 99.0 mass% or less, for example, 20.0 mass% or more and 99.0 mass% or less, 30.0 mass% or more and 99.0 mass% or less, 40.0 mass% or more and 99.0 mass% or less, 50.0 mass% or more and 99.0 mass% or less, 60.0 mass% or more and 99.0 mass% or less, 70.0 mass% or more and 99.0 mass% or less, 80.0 mass% or more and 99.0 mass% or less, 90.0 mass% or more and 99.0 mass% or less, 10.0 mass% or more and 90.0 mass% or less, 20.0 mass% or more and 90.0 mass% or less, 30.0 mass% or more and 90.0 mass% or less, 40.0 mass% or more and 90.0 mass% or less, 50.0 mass% or more and 90.0 mass% or less, 60.0 mass% or more and 90.0 mass% or less, 70.0 mass% or more and 90.0 mass% or less, 80.0 mass% or more and 90.0 mass% or less, 10.0 mass% or more and 80.0 mass% or less, 20.0 mass% or more and 80.0 mass% or less, 30.0 mass% or more and 80.0 mass% or less, 40.0 mass% or more and 80.0 mass% or less, 50.0 mass% or more and 80.0 mass% or less, 60.0 mass% or more and 80.0 mass% or less, 70.0 mass% or more and 80.0 mass% or less, 10.0 mass% or more and 70.0 mass% or less, 20.0 mass% or more and 70.0 mass% or less, 30.0 mass% or more and 70.0 mass% or less, 40.0 mass% or more and 70.0 mass% or less, 50.0 mass% or more and 60.0 mass% or less, 60.0 mass% or more and 70.0 mass% or less, 10.0 mass% or more and 60.0 mass% or less, 20.0 mass% or more and 60.0 mass% or less, 30.0 mass% or more and 60.0 mass% or less, 40.0 mass% or more and 60.0 mass% or less, 50.0 mass% or more and 60.0 mass% or less, 10.0 mass% or more and 50.0 mass% or less, 20.0 mass% or more and 50.0 mass% or less, 30.0 mass% or more and 50.0 mass% or less, 40.0 mass% or more and 50.0 mass% or less, 10.0 mass% or more and 40.0 mass% or less, 20.0 mass% or more and 40.0 mass% or less, 30.0 mass% or more and 40.0 mass% or less, 10.0 mass% or more and 30.0 mass% or less, 20.0 mass% or more and 30.0 mass% or less, or 10.0 mass% or more and 20.0 mass% or less, based on the total mass of the copper oxide-coated particles 310.

[0072] According to an embodiment, the copper oxide coated particles 310 have a blackness of 150 to 165 inclusive before a clear coat is applied, such as 152 to 165 inclusive, 155 to 165 inclusive, 155 to 165 inclusive, 158 to 165 inclusive, 160 to 165 inclusive, 162 to 165 inclusive, 150 to 162 inclusive, 152 to 162 inclusive, 155 to 162 inclusive, 158 to 162 inclusive, 160 to 162 inclusive, 150 to 160 inclusive, 152 to 160 inclusive, 155 to 160 inclusive, 158 to 160 inclusive, 150 to 158 inclusive, 152 to 158 inclusive, 155 to 158 inclusive, 150 to 155 inclusive, 152 to 155 inclusive, or 150 to 152 inclusive.

[0073] The blackness of an embodiment of copper oxide-coated cobalt oxide is shown in Figure 4A in comparison with other materials before a clear coat is applied. As can be seen from Figure 4A, the standard (STD), carbon black, and uncoated cobalt oxide (Co3O4) all have a blackness of approximately 165, which is the standard for pigments used in true black applications, such as paints in general and automotive paints in particular. Figure 4A also shows that the blackness of cool black (a chromium-based pigment commonly used in multiple applications), bulk CuO, and CuO nanoparticles (nano-CuO) are all significantly below the standard for pigments used in true black applications. However, copper oxide-coated cobalt oxide (CuO-Co3O4) has a blackness similar to the standard for pigments used in true black applications, such as paints in general and automotive paints in particular.

[0074] Figure 4B shows the blackness of an embodiment of copper oxide-coated carbon black compared to other materials after a clear coat was applied to the sample. As can be seen from Figure 4B, the carbon black has a blackness of approximately 135, which is the standard for pigments used in true black applications, such as paints in general and automotive paints in particular. Figure 4B also shows that the blackness of cool black (a chromium-based pigment commonly used in several applications), bulk (commercially available) CuO, CuO nanoparticles (nano-CuO), a 50:50 mixture of CuO and carbon black, and a 25:75 mixture of CuO and carbon black all fall well below the standard for pigments used in true black applications. However, the 50:50 copper oxide-coated carbon black and the 25:75 copper oxide-coated carbon black have blacknesses similar to the standard for pigments used in true black applications, such as paints in general and automotive paints in particular.

[0075] Another way to measure the blackness of a particle is by its reflectance for electromagnetic radiation in the visible spectrum. According to embodiments, the copper oxide coated particles 310 have a reflectance for electromagnetic radiation in the visible spectrum of 5.0% or less, e.g., 4.5% or less, 4.0% or less, 3.5% or less, 3.0% or less, 2.5% or less, 2.0% or less, 1.5% or less, 1.0% or less, or 0.5% or less, as measured by a UV-Vis-NIR spectrophotometer. In one or more embodiments, the copper oxide coated particles have a reflectance for electromagnetic radiation in the visible spectrum of 0.5% to 5.0%, e.g., 0.5% to 4.5%, 0.5% to 4.0%, 0.5% to 3.5%, 0.5% to 3.0%, 0.5% to 2.5%, 0.5% to 2.0%, 0.5% to 1.5%, or 0.5%. 1.0% or more, 5.0% or less, 1.0% or more and 4.5%, 1.0% or more and 4.0%, 1.0% or more and 3.5%, 1.0% or more and 3.0% or less, 1.0% or more 2.5% or less, 1.0% to 2.0%, 1.0% to 1.5%, 1.5% to 5.0%, 1.5% to 4.5%, 1.5% to 4.0%, 1.5% to 3.5% , 1.5% to 3.0%, 1.5% to 2.5%, 1.5% to 2.0%, 2.0% to 5.0%, 2.0% to 4.5%, 2.0% to 4.0%, 2 .0% to 3.5%, 2.0% to 3.0%, 2.0% to 2.5%, 2.5% to 5.0%, 2.5% to 4.5%, 2.5% to 4.0%, 2.5 % or more and 3.5% or less, 2.5% or more and 3.0% or less, 3.0% or more and 5.0% or less, 3.0% or more and 4.5% or less, 3.0% or more and 4.0% or less, 3.0% or more and 3.5% or less, 3.5% or more and 5.0% or less, 3.5% or more and 4.5% or less, 3.5% or more and 4.0% or less, 4.0% or more and 5.0% or less, 4.0% or more and 4.5% or less, or 4.5% or more and 5.0% or less.

[0076] Copper oxide coated particles according to embodiments disclosed and described herein also reflect electromagnetic radiation in the near-IR and LiDAR spectrums in addition to absorbing electromagnetic radiation in the visible spectrum. According to one or more embodiments, the copper oxide coated particles have a reflectivity of 5% or more, e.g., 10% or more, 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, 45% or more, 50% or more, 60% or more, or 65% or more, for electromagnetic radiation in the near-IR and LiDAR spectrums. In one or more embodiments, the copper oxide coated particles have a reflectivity for electromagnetic radiation in the near-IR and LiDAR spectrum of 5% to 65% inclusive, e.g., 5% to 60% inclusive, 5% to 55% inclusive, 5% to 50% inclusive, 5% to 45% inclusive, 5% to 40% inclusive, 5% to 35% inclusive, 5% to 30% inclusive, 5% to 25% inclusive, 5% to 20% inclusive, 5% to 15% inclusive, 5% to 10% inclusive, etc. In one or more embodiments, the copper oxide coated particles have a reflectivity for electromagnetic radiation in the near-IR and LiDAR spectrum of, for example, 10% to 65%, 10% to 60%, 10% to 55%, 10% to 50%, 10% to 45%, 10% to 40%, 10% to 35%, 10% to 30%, 10% to 25%, 10% to 20%, or 10% to 15%.

[0077] Next, a method for forming copper oxide-coated cobalt oxide according to embodiments disclosed and described herein will be described. One method for depositing copper oxide on cobalt oxide is atomic layer deposition (ALD). ALD is a deposition technique that uses sequential gas-phase chemical processes. ALD uses a self-limiting, sequential reaction of two chemical precursors that react with the surface of the cobalt oxide particles. By repeated exposure to the different chemical precursors, a copper oxide film is slowly deposited on the cobalt oxide particles. For example, a first precursor reacts with the reaction sites on the surface of the cobalt oxide particles, and excess first precursor is purged from the system. Once the excess first precursor is purged, a second precursor is introduced into the system. The second precursor reacts with the first precursor to form a copper oxide layer on the surface of the cobalt oxide, and excess second precursor is purged from the system. Suitable copper precursors according to embodiments include Cu(NO), CuCl, CuSO, Cu(CHCOO), and combinations thereof.

[0078] Although ALD is a technically viable method for depositing copper oxide on cobalt oxide, the ALD process is expensive, time-consuming, and difficult to scale up to commercially viable levels. Therefore, other methods for depositing copper oxide on cobalt oxide include wet chemical methods.

[0079] According to an embodiment, a first usable wet chemical method begins with a solution of copper nitrate (Cu(NO)) having a concentration of 0.0001M to 0.1M, inclusive, and cobalt oxide (CoO) particles in the Cu(NO) solution. Sodium hydroxide (NaOH) at a concentration of 0.1M to 1M, inclusive, is introduced to the solution as a precipitant. The Cu(NO) reacts with the NaOH precipitant to form copper hydroxide (Cu(OH)) and sodium nitrate (NaNO). The Cu(OH) and NaNO begin to coat the CoO particles, thereby forming Cu(OH) and NaNO-coated CoO. Some Cu(OH) and / or NaNO precipitate out of solution. According to an embodiment, the mixture is stored at room temperature overnight (e.g., for 8 to 15 hours). The NaNO on the Co3O4 particles is removed by washing with water, ethanol, or a mixture of water and ethanol. After washing with water and ethanol, the solution is filtered to obtain Cu(OH2)-coated Co3O4. The Cu(OH)2-coated Co3O4 is then dried at a temperature of 100°C to 140°C for 0.5 to 5.0 hours.

[0080] According to the embodiment, the Cu(OH)2-coated Co3O4 is heated to 105°C or higher and 140°C or lower, for example, 110°C or higher and 140°C or lower, 115°C or higher and 140°C or lower, 120°C or higher and 140°C or lower, 125°C or higher and 140°C or lower, 130°C or higher and 140°C or lower, 135°C or higher and 140°C or lower, 100°C or higher and 135°C or lower, 105°C or higher and 135°C or lower, 110°C or higher and 135°C or lower, 115°C or higher and 135°C or lower, 120°C or higher and 135°C or lower, 125°C or higher and 135°C or lower, 130°C or higher and 135 .... The drying temperature may be from 100°C to 130°C, from 105°C to 130°C, from 110°C to 130°C, from 115°C to 130°C, from 120°C to 130°C, from 125°C to 130°C, from 100°C to 125°C, from 105°C to 125°C, from 110°C to 125°C, from 115°C to 125°C, from 120°C to 125°C, from 100°C to 120°C, from 105°C to 120°C, from 110°C to 120°C, from 115°C to 120°C, from 100°C to 115°C, from 105°C to 115°C, from 110°C to 115°C, from 100°C to 110°C, from 105°C to 110°C, or from 100°C to 105°C.

[0081] According to an embodiment, the Cu(OH)2-coated Co3O4 is heated for 1.0 hours or more and 5.0 hours or less, for example, 1.5 hours or more and 5.0 hours or less, 2.0 hours or more and 5.0 hours or less, 2.5 hours or more and 5.0 hours or less, 3.0 hours or more and 5.0 hours or less, 3.5 hours or more and 5.0 hours or less, 4.0 hours or more and 5.0 hours or less, 4.5 hours or more and 5.0 hours or less, 0.5 hours or more and 4.5 hours or less, 1.0 hour or more and 4.5 hours or less. 1.5 hours to 4.5 hours, 2.0 hours to 4.5 hours, 2.5 hours to 4.5 hours, 3.0 hours to 4.5 hours, 3.5 hours to 4.5 hours, 4.0 hours to 4 .5 hours or less, 0.5 hours to 4.0 hours, 1.0 hours to 4.0 hours, 1.5 hours to 4.0 hours, 2.0 hours to 4.0 hours, 2.5 hours to 4.0 hours, 3.0 hours or less Above 4.0 hours or less, 3.5 hours or more and 4.0 hours or less, 0.5 hours or more and 3.5 hours or more, 1.0 hours or more and 3.5 hours or less, 1.5 hours or more and 3.5 hours or less, 2.0 hours or more and 3.5 hours or less, 2.5 3.5 hours or more, 3.0 hours or more and 3.5 hours or more, 0.5 hours or more and 3.0 hours or more, 1.0 hours or more and 3.0 hours or more, 1.5 hours or more and 3.0 hours or less, 2.0 hours or more and 3.0 hours or less, 2 The drying time may be from 0.5 to 3.0 hours, from 0.5 to 2.5 hours, from 1.0 to 2.5 hours, from 1.5 to 2.5 hours, from 2.0 to 2.5 hours, from 0.5 to 2.0 hours, from 1.0 to 2.0 hours, from 1.5 to 2.0 hours, from 0.5 to 1.5 hours, from 1.0 to 1.5 hours, or from 0.5 to 1.0 hour.

[0082] The dried Cu(OH)2-coated Co3O4 is, according to an embodiment, calcined at a temperature of 430°C to 470°C for a time period of 0.5 hours to 5.0 hours.

[0083] In one or more embodiments, the dried Cu(OH)2-coated Co3O4 is heated to 435°C or higher and 470°C or lower, e.g., 440°C or higher and 470°C or lower, 445°C or higher and 470°C or lower, 450°C or higher and 470°C or lower, 455°C or higher and 470°C or lower, 460°C or higher and 470°C or lower, 465°C or higher and 470°C or lower, 430°C or higher and 465°C or lower, 435°C or higher and 465°C or lower, 440°C or higher and 465°C or lower, 445°C or higher and 465°C or lower, 450°C or higher and 465°C or lower, 455°C or higher and 465°C or lower, 460°C or higher and 465°C or lower, 430°C or higher and 460°C or lower, 435°C or higher and 460°C or lower, 440°C or higher and 465°C or lower, 440°C or higher and 465°C or lower, 450°C or higher and 465°C or lower, 455°C or higher and 465°C or lower, 430°C or higher and 460°C or lower, 435°C or higher and 460°C or lower, 440°C or higher and 465°C or lower, 440°C or higher and 465°C or lower, 430°C or higher and 460°C or lower, 435°C or higher and 460°C or lower, 440°C or higher and 465°C The firing temperature may be 60°C or less, 445°C to 460°C, 450°C to 460°C, 455°C to 460°C, 430°C to 455°C, 435°C to 455°C, 440°C to 455°C, 445°C to 455°C, 450°C to 455°C, 430°C to 450°C, 435°C to 450°C, 440°C to 450°C, 445°C to 450°C, 430°C to 445°C, 435°C to 445°C, 440°C to 445°C, 430°C to 440°C, 435°C to 440°C, or 430°C to 435°C.

[0084] According to an embodiment, the dried Cu(OH)2-coated Co3O4 is heated for 1.0 to 5.0 hours, e.g., 1.5 to 5.0 hours, 2.0 to 5.0 hours, 2.5 to 5.0 hours, 3.0 to 5.0 hours, 3.5 to 5.0 hours, 4.0 to 5.0 hours, 4.5 to 5.0 hours, 0.5 to 4.5 hours, 1.0 hour or more, or 4.5 hours or less, 1.5 hours to 4.5 hours, 2.0 hours to 4.5 hours, 2.5 hours to 4.5 hours, 3.0 hours to 4.5 hours, 3.5 hours to 4.5 hours, 4.0 hours More than 4.5 hours, 0.5 hours to 4.0 hours, 1.0 hours to 4.0 hours, 1.5 hours to 4.0 hours, 2.0 hours to 4.0 hours, 2.5 hours to 4.0 hours, 3.0 hours 3.5 hours to 4.0 hours, 0.5 hours to 3.5 hours, 1.0 hours to 3.5 hours, 1.5 hours to 3.5 hours, 2.0 hours to 3.5 hours, 2. 5 hours to 3.5 hours, 3.0 hours to 3.5 hours, 0.5 hours to 3.0 hours, 1.0 hours to 3.0 hours, 1.5 hours to 3.0 hours, 2.0 hours to 3.0 hours, 2 It is baked for a time such as 0.5 to 3.0 hours, 0.5 to 2.5 hours, 1.0 to 2.5 hours, 1.5 to 2.5 hours, 2.0 to 2.5 hours, 0.5 to 2.0 hours, 1.0 to 2.0 hours, 1.5 to 2.0 hours, 0.5 to 1.5 hours, 1.0 to 1.5 hours, or 0.5 to 1.0 hour.

[0085] After calcination, copper oxide (CuO) coated cobalt oxide (Co3O4) particles were obtained.

[0086] According to an embodiment, a second wet chemical method that can be used starts with a solution of copper nitrate (Cu(NO)) having a concentration of 0.0001M to 0.1M and cobalt oxide (CoO) particles in the Cu(NO) solution. Sodium carbonate (NaCO) is introduced into the solution as a precipitating agent. The Cu(NO) and NaCO precipitating agents react to form copper carbonate (CuCO) and sodium nitrate (NaNO) precipitates. The CuCO and NaNO begin to coat the CoO particles, thereby forming CuCO and NaNO-coated CoO. Some CuCO and / or NaNO precipitate out of solution. According to an embodiment, the mixture may be stored overnight (e.g., 8 hours to 15 hours) at room temperature (e.g., 20°C to 25°C). The NaNO on the CoO particles is removed by washing with water, ethanol, or a mixture of water and ethanol. After washing with water and ethanol, the solution was filtered to obtain CuCO3-coated Co3O4, which was then dried at a temperature of 100°C to 140°C for 0.5 to 5.0 hours.

[0087] According to the embodiment, the CuCO3-coated Co3O4 is heated to 105°C or higher and 140°C or lower, for example, 110°C or higher and 140°C or lower, 115°C or higher and 140°C or lower, 120°C or higher and 140°C or lower, 125°C or higher and 140°C or lower, 130°C or higher and 140°C or lower, 135°C or higher and 140°C or lower, 100°C or higher and 135°C or lower, 105°C or higher and 135°C or lower, 110°C or lower Upper 135℃ or lower, 115℃ or higher and 135℃ or lower, 120℃ or higher and 135℃ or lower, 125℃ or higher and 135℃ or lower, 130℃ or higher and 135℃ or lower, 100℃ or higher and 135℃ or lower, 10 5℃ to 135℃, 110℃ to 135℃, 115℃ to 135℃, 120℃ to 135℃, 125℃ to 135℃, 100℃ to 135℃ , 130℃ to 135℃, 100℃ to 130℃, 105℃ to 130℃, 110℃ to 130℃, 115℃ to 130℃, 120℃ to 130 ℃ or less, 125℃ or more and 130℃ or less, 100℃ or more and 125℃ or less, 105℃ or more and 125℃ or less, 110℃ or more and 125℃ or less, 115℃ or more and 125℃ or less, 120℃ or more Drying is performed at a temperature such as 125°C or less, 100°C to 120°C, 105°C to 120°C, 110°C to 120°C, 115°C to 120°C, 100°C to 115°C, 105°C to 115°C, 110°C to 115°C, 100°C to 110°C, 105°C to 110°C, or 100°C to 105°C.

[0088] According to an embodiment, the CuCO3-coated Co3O4 is heated for 1.0 hours or more and 5.0 hours or less, for example, 1.5 hours or more and 5.0 hours or less, 2.0 hours or more and 5.0 hours or less, 2.5 hours or more and 5.0 hours or less, 3.0 hours or more and 5.0 hours or less, 3.5 hours or more and 5.0 hours or less, 4.0 hours or more and 5.0 hours or less, 4.5 hours or more and 5.0 hours or less, 0.5 hours or more and 4.5 hours or less, 1.0 hour or more and 4.5 hours or less. The following: 1.5 hours to 4.5 hours, 2.0 hours to 4.5 hours, 2.5 hours to 4.5 hours, 3.0 hours to 4.5 hours, 3.5 hours to 4.5 hours, 4.0 hours to 4. 5 hours or less, 0.5 hours to 4.0 hours, 1.0 hours to 4.0 hours, 1.5 hours to 4.0 hours, 2.0 hours to 4.0 hours, 2.5 hours to 4.0 hours, 3.0 hours or more 4.0 hours or less, 3.5 hours to 4.0 hours, 0.5 hours to 3.5 hours, 1.0 hours to 3.5 hours, 1.5 hours to 3.5 hours, 2.0 hours to 3.5 hours, 2.5 hours 3.0 hours to 3.5 hours, 0.5 hours to 3.0 hours, 1.0 hours to 3.0 hours, 1.5 hours to 3.0 hours, 2.0 hours to 3.0 hours, 2 It is dried for a period of time such as 0.5 to 3.0 hours, 0.5 to 2.5 hours, 1.0 to 2.5 hours, 1.5 to 2.5 hours, 2.0 to 2.5 hours, 0.5 to 2.0 hours, 1.0 to 2.0 hours, 1.5 to 2.0 hours, 0.5 to 1.5 hours, 1.0 to 1.5 hours, or 0.5 to 1.0 hour.

[0089] The dried CuCO3-coated Co3O4 is, according to an embodiment, calcined at a temperature of 430°C to 470°C for a time period of 0.5 hours to 5.0 hours.

[0090] In one or more embodiments, the dried Cu(OH)2-coated Co3O4 is heated to a temperature of 435° C. to 470° C., e.g., 440° C. to 470° C., 445° C. to 470° C., 450° C. to 470° C., 455° C. to 470° C., 460° C. to 470° C., 465° C. to 470° C., 430° C. to 465° C., 435° C. to 465° C., 440° C. to 465° C., 445° C. to 465° C., 450° C. to 465° C., 455° C. to 465° C., 460° C. to 465° C., 430° C. to 460° C., 435° C. to 460° C., 440° C. to 465° C., The firing temperature may be 460°C or less, 445°C to 460°C, 450°C to 460°C, 455°C to 460°C, 430°C to 455°C, 435°C to 455°C, 440°C to 455°C, 445°C to 455°C, 450°C to 455°C, 430°C to 450°C, 435°C to 450°C, 440°C to 450°C, 445°C to 450°C, 430°C to 445°C, 435°C to 445°C, 440°C to 445°C, 430°C to 440°C, 435°C to 440°C, or 430°C to 435°C.

[0091] According to an embodiment, the dried CuCO3-coated Co3O4 is heated for 1.0 to 5.0 hours, e.g., 1.5 to 5.0 hours, 2.0 to 5.0 hours, 2.5 to 5.0 hours, 3.0 to 5.0 hours, 3.5 to 5.0 hours, 4.0 to 5.0 hours, 4.5 to 5.0 hours, 0.5 to 4.5 hours, 1.0 to 4. 5 hours or less, 1.5 hours to 4.5 hours, 2.0 hours to 4.5 hours, 2.5 hours to 4.5 hours, 3.0 hours to 4.5 hours, 3.5 hours to 4.5 hours, 4.0 hours or more 4.5 hours or less, 0.5 hours to 4.0 hours, 1.0 hours to 4.0 hours, 1.5 hours to 4.0 hours, 2.0 hours to 4.0 hours, 2.5 hours to 4.0 hours, 3.0 hours More than 4.0 hours, 3.5 hours to 4.0 hours, 0.5 hours to 3.5 hours, 1.0 hours to 3.5 hours, 1.5 hours to 3.5 hours, 2.0 hours to 3.5 hours, 2.5 3.5 hours or more, 3.0 hours or more and 3.5 hours or more, 0.5 hours or more and 3.0 hours or more, 1.0 hours or more and 3.0 hours or more, 1.5 hours or more and 3.0 hours or less, 2.0 hours or more and 3.0 hours or less, 2 It is baked for a time such as 0.5 to 3.0 hours, 0.5 to 2.5 hours, 1.0 to 2.5 hours, 1.5 to 2.5 hours, 2.0 to 2.5 hours, 0.5 to 2.0 hours, 1.0 to 2.0 hours, 1.5 to 2.0 hours, 0.5 to 1.5 hours, 1.0 to 1.5 hours, or 0.5 to 1.0 hour.

[0092] After calcination, copper oxide (CuO)-coated cobalt oxide (Co3O4) particles are obtained. According to embodiments, the Co3O4 particles originally present in the Cu(NO3)2 solution may be replaced with a cobalt nitrate (Co(NO3)2) solution. According to one or more embodiments, the cobalt to copper ratio is 1:1 or greater and 9:1 or less, e.g., 1:1 or greater and 8:1 or less, 1:1 or greater and 7:1 or less, 1:1 or greater and 6:1 or less, 1:1 or greater and 5:1 or less, 1:1 or greater and 4:1 or less, 1:1 or greater and 3:1 or less, or 1:1 or greater and 2:1 or less. According to embodiments, the precipitating agent may include NaOH, Na2CO3, (NH4)2CO3, and mixtures thereof.

[0093] According to an embodiment, a third wet chemical method that can be used starts with a solution of copper nitrate (Cu(NO)) having a concentration of 0.0001M or more and 0.1M or less, and cobalt oxide (CoO) particles in this solution of Cu(NO). Ammonium carbonate ((NH)CO) is introduced into the solution as a precipitant. In this wet chemical method, an ammonium-based precipitant is used instead of the sodium-based precipitant used in the first and second wet chemical methods. The sodium-based precipitant forms a sodium-based precipitate that can inhibit the reaction and reduce the yield of CuO-coated CoO. The Cu(NO) and (NH)CO precipitants react to form copper carbonate (CuCO) and ammonium nitrate ((NH)NO) precipitates. The CuCO3 and (NH4)2NO3 begin to coat the Co3O4 particles, thereby forming CuCO3 and (NH4)2NO3-coated Co3O4. Some CuCO3 and / or (NH4)2NO3 precipitates out of solution. According to an embodiment, the mixture may be stored overnight (e.g., 8 hours to 15 hours) at room temperature (e.g., 20°C to 25°C). The (NH4)2NO3 on the Co3O4 particles is removed by washing with water, ethanol, or a mixture of water and ethanol. After washing with water and ethanol, the solution is filtered to obtain CuCO3-coated Co3O4. The CuCO3-coated Co3O4 is then dried at a temperature of 100°C to 140°C for 0.5 hours to 5.0 hours.

[0094] According to the embodiment, the CuCO3-coated Co3O4 is heated to 105°C or higher and 140°C or lower, for example, 110°C or higher and 140°C or lower, 115°C or higher and 140°C or lower, 120°C or higher and 140°C or lower, 125°C or higher and 140°C or lower, 130°C or higher and 140°C or lower, 135°C or higher and 140°C or lower, 100°C or higher and 135°C or lower, 105°C or higher and 135°C or lower, 110°C or higher and 135°C or lower, 115°C or higher and 135°C or lower, 120°C or higher and 135°C or lower, 125°C or higher and 135°C or lower, 130°C or higher and 135 ... Drying is performed at temperatures such as 135°C or less, 100°C to 130°C, 105°C to 130°C, 110°C to 130°C, 115°C to 130°C, 120°C to 130°C, 125°C to 130°C, 100°C to 125°C, 105°C to 125°C, 110°C to 125°C, 115°C to 125°C, 120°C to 125°C, 100°C to 120°C, 105°C to 120°C, 110°C to 120°C, 115°C to 120°C, 100°C to 115°C, 105°C to 115°C, 110°C to 115°C, 100°C to 110°C, 105°C to 110°C, or 100°C to 105°C.

[0095] According to an embodiment, the CuCO3-coated Co3O4 is heated for 1 hour or more and 5 hours or less, for example, 1.5 hours or more and 5.0 hours or less, 2.0 hours or more and 5.0 hours or less, 2.5 hours or more and 5.0 hours or less, 3.0 hours or more and 5.0 hours or less, 3.5 hours or more and 5.0 hours or less, 4.0 hours or more and 5.0 hours or less, 4.5 hours or more and 5.0 hours or less, 0.5 hours or more and 4.5 hours or less, 1.0 hours or more and 4.5 hours or less, 1.5 hours or more and 5.0 hours or less. 2.0 to 4.5 hours, 2.5 to 4.5 hours, 3.0 to 4.5 hours, 3.5 to 4.5 hours, 4.0 to 4.5 hours, 0.5 to 4.0 hours, 1.0 to 4.0 hours, 1.5 to 4.0 hours, 2.0 to 4.0 hours, 2.5 to 4.0 hours, 2.5 to 4.0 hours, 3.0 hours to 4.0 hours, 3.5 hours to 4.0 hours, 0.5 hours to 3.5 hours, 1.0 hours to 3.5 hours, 1.5 hours to 3.5 hours, 2.0 hours to 3.5 hours Bottom, 2.5 hours to 3.5 hours, 3 hours to 3.5 hours, 0.5 hours to 3.0 hours, 1.0 hours to 3.0 hours, 1.5 hours to 3.0 hours, 2.0 hours to 3.0 hours The drying time may be 2.5 to 3.0 hours, 0.5 to 2.5 hours, 1.0 to 2.5 hours, 1.5 to 2.5 hours, 2.0 to 2.5 hours, 0.5 to 2.0 hours, 1.0 to 2.0 hours, 1.5 to 2.0 hours, 0.5 to 1.5 hours, 1.0 to 1.5 hours, or 0.5 to 1.0 hour.

[0096] The dried CuCO3-coated Co3O4 is, according to an embodiment, calcined at a temperature of 430°C to 470°C for a time period of 0.5 hours to 5.0 hours.

[0097] In one or more embodiments, the dried Cu(OH)2-coated Co3O4 is heated to 435°C or higher and 470°C or lower, e.g., 440°C or higher and 470°C or lower, 445°C or higher and 470°C or lower, 450°C or higher and 470°C or lower, 455°C or higher and 470°C or lower, 460°C or higher and 470°C or lower, 465°C or higher and 470°C or lower, 430°C or higher and 465°C or lower, 435°C or higher and 465°C or lower, 440°C or higher and 465°C or lower, 445°C or higher and 465°C or lower, 450°C or higher and 465°C or lower, 455°C or higher and 465°C or lower, 460°C or higher and 465°C or lower, 430°C or higher and 460°C or lower, 435°C or higher and 460°C or lower, 440°C or higher and 465°C or lower, 440°C or higher and 465°C or lower, 450°C or higher and 465°C or lower, 455°C or higher and 465°C or lower, 430°C or higher and 460°C or lower, 435°C or higher and 460°C or lower, 440°C or higher and 465°C or lower, 440°C or higher and 465°C or lower, 430°C or higher and 460°C or lower, 435°C or higher and 460°C or lower, 440°C or higher and 465°C It is fired at temperatures such as 60°C or less, 445°C or more to 460°C or less, 450°C or more to 460°C or less, 455°C or more to 460°C or less, 430°C or more to 455°C or less, 435°C or more to 455°C or less, 440°C or more to 455°C or less, 445°C or more to 455°C or less, 450°C or more to 455°C or less, 430°C or more to 450°C or less, 435°C or more to 450°C or less, 440°C or more to 450°C or less, 445°C or more to 450°C or less, 430°C or more to 445°C or less, 435°C or more to 445°C or less, 440°C or more to 445°C or less, 430°C or more to 440°C or less, 435°C or more to 440°C or less, or 430°C or more to 435°C or less.

[0098] According to an embodiment, the dried CuCO3-coated Co3O4 is heated for 1.0 to 5.0 hours, e.g., 1.5 to 5.0 hours, 2.0 to 5.0 hours, 2.5 to 5.0 hours, 3.0 to 5.0 hours, 3.5 to 5.0 hours, 4.0 to 5.0 hours, 4.5 to 5.0 hours, 0.5 to 4.5 hours, 1.0 to 4. .5 hours or less, 1.5 hours to 4.5 hours, 2.0 hours to 4.5 hours, 2.5 hours to 4.5 hours, 3.0 hours to 4.5 hours, 3.5 hours to 4.5 hours, 4.0 hours or less 4.5 hours or less, 0.5 to 4.0 hours, 1.0 to 4.0 hours, 1.5 to 4.0 hours, 2.0 to 4.0 hours, 2.5 to 4.0 hours, 3.0 hours 3.5 hours to 4.0 hours, 0.5 hours to 3.5 hours, 1.0 hours to 3.5 hours, 1.5 hours to 3.5 hours, 2.0 hours to 3.5 hours, 2. 5 hours to 3.5 hours, 3.0 hours to 3.5 hours, 0.5 hours to 3.0 hours, 1.0 hours to 3.0 hours, 1.5 hours to 3.0 hours, 2.0 hours to 3.0 hours, It is baked for a time such as 2.5 to 3.0 hours, 0.5 to 2.5 hours, 1.0 to 2.5 hours, 1.5 to 2.5 hours, 2.0 to 2.5 hours, 0.5 to 2.0 hours, 1.0 to 2.0 hours, 1.5 to 2.0 hours, 0.5 to 1.5 hours, 1.0 to 1.5 hours, or 0.5 to 1.0 hour.

[0099] After calcination, copper oxide (CuO) coated cobalt oxide (Co3O4) particles were obtained.

[0100] Next, a method for forming copper oxide (CuO)-coated carbon black particles will be described.

[0101] A thin layer of CuO can be applied to the surface of carbon black by ALD similar to the method for depositing CuO on Co3O4 described above, but by using the precursors disclosed above, CuO can be deposited on carbon black particles.

[0102] As disclosed above, ALD is a technically viable method for depositing copper oxide on the surface of carbon black, but the ALD process is expensive, time-consuming, and difficult to scale up to commercially viable levels. Therefore, other methods for depositing copper oxide on carbon black include wet chemical methods.

[0103] According to an embodiment, a usable wet chemical method begins with a solution of copper nitrate (Cu(NO)) having a concentration of 0.0001M or more and 0.1M or less, and carbon black particles in this solution of Cu(NO). NaCO, (NH)CO, or NaOH is introduced into the solution as a precipitating agent. A certain ratio of Cu(NO) reacts with the precipitating agent to form a Cu(OH) or CuCO (depending on the precipitating agent) and a NaNO or (NH)NO precipitate (depending on the precipitating agent). The (Cu(OH)) and / or CuCO coat the carbon black particles. The precipitate is then washed with water and ethanol to remove the NaNO and / or (NH)NO. The solution is then filtered to obtain Cu(OH)-coated carbon black or CuCO-coated carbon black. The precipitate is then dried at a temperature of 100° C. to 140° C. for a period of 5 hours to 15 hours.

[0104] According to an embodiment, the CuCO and / or Cu(OH) coated carbon black is heated to a temperature of 105°C or higher and 140°C or lower, for example, 110°C or higher and 140°C or lower, 115°C or higher and 140°C or lower, 120°C or higher and 140°C or lower, 125°C or higher and 140°C or lower, 130°C or higher and 140°C or lower, 135°C or higher and 140°C or lower, 100°C or higher and 135°C or lower, 105°C or higher and 135°C or lower, 110°C or higher and 135°C or lower, 115°C or higher and 135°C or lower, 120°C or higher and 135°C or lower, 125°C or higher and 135°C or lower, 130°C or higher and 135°C or lower, 100°C or higher and 135°C or lower, 105°C or higher and 135°C or lower, 110°C or higher and 135°C or lower, 115°C or higher and 135°C or lower, 120°C or higher and 135°C or lower, 125°C or higher and 135°C or lower. Lower, 130℃ to 135℃, 100℃ to 130℃, 105℃ to 130℃, 110℃ to 130℃, 115℃ to 130℃, 120℃ to 13 Below 0°C, above 125°C and below 130°C, above 100°C and below 125°C, above 105°C and below 125°C, above 110°C and below 125°C, above 115°C and below 125°C, above 120°C The drying temperature may be from 100°C to 120°C, from 105°C to 120°C, from 110°C to 120°C, from 115°C to 120°C, from 100°C to 115°C, from 105°C to 115°C, from 110°C to 115°C, from 100°C to 110°C, from 105°C to 110°C, or from 100°C to 105°C.

[0105] According to an embodiment, the CuCO and / or Cu(OH) coated carbon black can be cured for 6 hours or more and 15 hours or less, 7 hours or more and 15 hours or less, for example, 8 hours or more and 15 hours or less, 9 hours or more and 15 hours or less, 10 hours or more and 15 hours or less, 11 hours or more and 15 hours or less, 12 hours or more and 15 hours or less, 13 hours or more and 15 hours or less, 14 hours or more and 15 hours or less, 5 hours or more and 14 hours or less, 6 hours or more and 14 hours or less, 7 hours or more and 14 hours or less, 8 hours or more and 14 hours or less, 9 hours or more and 14 hours or less, 10 hours or more and 14 hours or less, 11 hours or more and 14 hours or less, 12 hours or more and 14 hours or less, 13 hours or more and 14 hours or less, 5 hours or more and 13 hours or less, 6 hours or more and 13 hours or less, 12 hours or more and 14 hours or less, 5 hours or more and 13 hours or less, 12 hours or more and 14 hours or less, 13 hours or more and 14 hours or less, The drying time may be from 5 to 12 hours, from 6 to 12 hours, from 7 to 12 hours, from 8 to 12 hours, from 9 to 12 hours, from 10 to 12 hours, from 11 to 12 hours, from 5 to 11 hours, from 6 to 11 hours, from 7 to 11 hours, from 8 to 11 hours, from 9 to 11 hours, from 10 to 11 hours, from 5 to 10 hours, from 6 to 10 hours, from 7 to 10 hours, from 8 to 10 hours, from 9 to 10 hours, from 5 to 9 hours, from 6 to 9 hours, from 7 to 9 hours, from 8 to 9 hours, from 5 to 8 hours, from 6 to 8 hours, from 7 to 8 hours, from 5 to 7 hours, from 6 to 7 hours, or from 5 to 6 hours.

[0106] According to an embodiment, the dried CuCO and / or Cu(OH) coated carbon black is calcined at a temperature of 200° C. to 300° C. for 0.5 to 5.0 hours, resulting in CuO coated carbon black.

[0107] In one or more embodiments, the dried CuCO and / or Cu(OH) coated carbon black is heated to a temperature of 210° C. or higher and 300° C. or lower, e.g., 220° C. or higher and 300° C. or lower, 230° C. or higher and 300° C. or lower, 240° C. or higher and 300° C. or lower, 250° C. or higher and 300° C. or lower, 260° C. or higher and 300° C. or lower, 270° C. or higher and 300° C. or lower, 280° C. or higher and 300° C. or lower, 290° C. or higher and 300° C. or lower, 200° C. or higher and 290° C. or lower, 210° C. or higher and 290° C. or lower, 220℃ to 290℃, 230℃ to 290℃, 240℃ to 290℃, 250℃ to 290℃, 260℃ to 290℃, 270℃ to 290℃, 280℃ to 290℃, 200℃ and above 280℃ or less, 210℃ or more and 280℃ or less, 220℃ or more and 280℃ or less, 230℃ or more and 280℃ or less, 240℃ or more and 280℃ or less, 250℃ or more and 280℃ or less, 260℃ or more and 280℃ or less, 270℃ or more and 280℃ or less, 200℃ to 270℃, 210℃ to 270℃, 220℃ to 270℃, 230℃ to 270℃, 240℃ to 270℃, 250℃ to 270℃, 260℃ to 270℃, 200℃ and above 260℃ or less, 210℃ or more and 260℃ or less, 220℃ or more and 260℃ or more, 230℃ or more, 260℃ or less, 240℃ or more and 260℃ or less, 250℃ or more and 260℃ or less, 200℃ or more and 250℃ or less, 210℃ or more and 250℃ or less , 220°C or more and 250°C or less, 230°C or more and 250°C or less, 240°C or more and 250°C or less, 200°C or more and 240°C or less, 210°C or more and 240°C or less, 220°C or more and 240°C or less, 230°C or more and 240°C or less, 200°C or more and 230°C or less, 210°C or more and 230°C or less, 220°C or more and 230°C or less, 200°C or more and 220°C or less, 210°C or more and 220°C or less, or 200°C or more and 210°C or less.

[0108] The method disclosed above can be used to form carbon black coated with scattering CuO nanoparticles. While any one or combination of NaCO, NaOH, or (NH)CO can be used in the process, (NH)CO generally provides better yields.

[0109] Referring again to FIG. 3 , an embodiment of a copper oxide-coated particle system 300 is further described, in which the particles can be copper oxide-coated cobalt oxide or copper oxide-coated carbon black. According to embodiments, the copper oxide-coated particle system 300 can be a paint layer having a plurality of copper oxide-coated particles 310 in a carrier 330. According to embodiments disclosed and described herein, the carrier 330 can be a binder or any type of solvent for the paint system, such as an organic solvent or water. Non-limiting examples of binders include enamel paint binders, urethane paint binders, combination enamel-urethane paint binders, acrylic binders, latex binders, and the like. In embodiments, the copper oxide-coated particle system 300 appears dark to an observer viewing the copper oxide-coated particle system 300 and can reflect electromagnetic radiation within the near-IR and LiDAR spectrum, such as electromagnetic radiation having wavelengths greater than about 750 nm to 1550 nm. That is, when exposed to sunlight and viewed by an observer, the near-IR and LiDAR reflective copper oxide coated particle system 300 has a color with a lightness in the CIELAB color space of 20 or less, and reflects, on average, more than 20% of electromagnetic radiation in the near-IR and LiDAR spectrum, e.g., electromagnetic radiation having wavelengths greater than about 750 nm to 1550 nm. In embodiments, the near-IR and LiDAR reflective copper oxide coated particle system 300, when exposed to sunlight, reflects, on average, less than 10% of electromagnetic radiation in the visible spectrum and has a lightness in the CIELAB color space of 15 or less. In such embodiments, the near-IR and LiDAR reflective copper oxide coated particle system 300, when exposed to sunlight, can have a lightness in the CIELAB color space of 10 or less. As used herein, the term "average" refers to the average of 10 reflectance values ​​equidistantly spaced along the specified reflectance spectrum of the near-IR and LiDAR reflective dark pigment or near-IR and LiDAR reflective copper oxide coated particle system 300 described herein. Additionally, in this specification, unless otherwise specified, the terms "reflects more than..." and "reflects less than..." mean "reflects more than average..." and "reflects less than average...", respectively.

[0110] However, in one or more embodiments, the copper oxide-coated particles 310 may be one of many different types of pigments and / or colorants in the carrier 330 of the copper oxide-coated particle system 300. For example, the copper oxide-coated particles 310 disclosed and described herein may be used in combination with other types of pigments and / or colorants added to the carrier to make the copper oxide-coated particle system darker. As a non-limiting example, to create a dark green copper oxide-coated particle system 300, the copper oxide-coated particles 310 may be added to the carrier 330 along with a conventional green pigment. The copper oxide-coated particles 310 in the dark green copper oxide-coated particle system 300 reflect a sufficient amount of near-IR or LiDAR electromagnetic radiation so that the dark green copper oxide-coated particle system 300 is detectable by a near-IR or LiDAR sensor. The copper oxide-coated particles according to the embodiments disclosed and described herein can be used in any paint system to darken the visual appearance of the paint system. Thus, the copper oxide coated particles disclosed and described herein can be used, without limitation, wherever black pigments, such as carbon black, cobalt oxide, and copper oxide, are used in paint or coloring systems.

[0111] 6 and 7, an embodiment of a vehicle "V" painted with the near-IR and LiDAR reflective dark paint having copper oxide coated particles as disclosed and described herein is depicted. In particular, FIG. 6 depicts vehicle V having a side panel S coated with near-IR and LiDAR reflective dark paint 50 having copper oxide coated particles as disclosed and described herein, and FIG. 7 depicts a cross section of one of side panels S having near-IR and LiDAR reflective dark paint 50. The near-IR and LiDAR reflective dark paint 50 may include multiple layers that provide surface protection and a desired color. For example, the near-IR and LiDAR reflective dark paint 50 may include a phosphate layer 122, an electrodeposit layer 124, a primer layer 126, a color layer 112 or 114 (also referred to as a base coat or base coat layer), and a clear coat layer 128. Non-limiting examples of phosphate layers include a manganese phosphate layer, an iron phosphate layer, a zinc phosphate layer, and combinations thereof. Non-limiting examples of electrodeposited layers include anodic electrodeposited layers and cathodic electrodeposited layers. Non-limiting examples of primer layers include epoxy primer layers and urethane primer layers. Non-limiting examples of clearcoat layers include urethane clearcoat layers and acrylic lacquer clearcoat layers. It should be understood that the near-IR and LiDAR reflective dark paint 50 appears dark to an observer viewing the near-IR and LiDAR reflective dark paint and reflects electromagnetic radiation within the near-IR and LiDAR spectrum, e.g., electromagnetic radiation having wavelengths from about greater than 750 nm to 1550 nm. That is, when exposed to sunlight and viewed by an observer, the near-IR and LiDAR reflective dark paint 50 has a color with a value of 20 or less in the CIELAB color space and reflects more than 40% of electromagnetic radiation within the near-IR and LiDAR spectrum, e.g., electromagnetic radiation having wavelengths from about greater than 750 nm to 1550 nm. In some embodiments, the near-IR and LiDAR reflective dark paint 50 exposed to sunlight reflects, on average, less than 10% of electromagnetic radiation in the visible spectrum and has a color value in the CIELAB color space of less than or equal to 15. In such embodiments, the LiDAR reflective dark paint 50 exposed to sunlight can have a color value in the CIELAB color space of less than or equal to 10.

[0112] The blackness of the paint system with the clearcoat may be lower than the blackness of the pigment itself. Without being bound by any particular theory, it is believed that the lower blackness value is due to less light scattering from the smooth surface of the clearcoat or less refractive index contrast caused by the clearcoat. According to embodiments, the near-IR and LiDAR reflective dark paint with copper oxide coated particles has a blackness of 100 to 140, e.g., 105 to 140, 110 to 140, 115 to 140, 120 to 140, 125 to 140, 130 to 140, 135 to 140, 100 to 135, 105 to 135, 110 to 135, 115 to 135, 120 to 135, 125 to 135, 130 to 135, 100 to 130, 105 to 14 ... The blackness may be 30 or less, 110 to 130, 115 to 130, 120 to 130, 125 to 130, 100 to 125, 105 to 125, 110 to 125, 115 to 125, 120 to 125, 100 to 120, 105 to 120, 110 to 120, 115 to 120, 100 to 115, 105 to 115, 110 to 115, 100 to 110, 105 to 110, or 100 to 105.

[0113] As described above, the near-IR and LiDAR reflective copper oxide coated particles according to embodiments disclosed and described herein can be used in paints to provide near-IR and LiDAR reflective dark articles that can be detected by systems that detect near-IR or LiDAR electromagnetic radiation. The types of articles that can be coated with the near-IR and LiDAR reflective paints according to embodiments disclosed and described herein are not limited. Objects such as automobiles, motorcycles, bicycles, buildings, doorways, road lines, signs, and articles in factories, shipyards, and warehouses can be coated with the near-IR and LiDAR reflective dark paints described herein to provide dark articles that have a desired dark color and are detectable by systems that detect electromagnetic radiation within the near-IR and LiDAR spectrum, such as electromagnetic radiation having wavelengths from greater than about 750 nm to 1550 nm. [Example]

[0114] The following examples further illustrate embodiments.

[0115] Example 1 - Synthesis of Copper Oxide-Coated Cobalt Oxide Pigment

[0116] The following example demonstrates the synthesis of a 1:1 CuO / CoO mixture, i.e., 50% CuO and 50% CoO, using NaCO as the precipitant. In a typical synthesis procedure, 14.6 grams of Cu(NO) were dissolved in 300 ml of water. Five grams of CoO were then dispersed in the Cu(NO) solution. In a separate container, 10 grams of NaCO were dissolved in 300 ml of water. The NaCO solution was then slowly added to the Cu(NO) / CoO solution until the precipitation of Cu(NO) to CuCO was complete. The precipitate was then aged overnight and filtered. The precipitate was then washed with 1000 ml of water and dried at 120°C for 12 hours at a ramp rate of 2°C / min. Finally, the material was calcined at 500° C. for 1 hour at a ramp rate of 5° C. / min.

[0117] The above process was repeated with copper oxide concentrations of 23% and 33% by weight. Figure 5 shows photographs of several copper oxide-coated cobalt oxide particles with varying percentages of copper oxide on the cobalt oxide, taken with an IR camera equipped with SOLOMARK digital night vision binoculars. Figure 5 shows the increase in reflectivity for electromagnetic radiation in the near-IR and LiDAR spectra as the mass percent of copper oxide in the copper oxide-coated cobalt oxide increases. The highest reflectivity shown in Figure 5 is for 100% copper oxide (the two groups labeled 510 in Figure 5). However, Figure 5 also shows significant reflectivity for the copper oxide-coated cobalt oxide particles as disclosed above. In particular, FIG. 5 shows the reflectivity for electromagnetic radiation in the near-IR and LiDAR spectra of copper oxide-coated cobalt oxide particles containing 23% copper oxide by weight (520), copper oxide-coated cobalt oxide particles containing 33% copper oxide by weight (530), and copper oxide-coated cobalt oxide particles containing 50% copper oxide by weight (540).

[0118] The blackness of copper oxide coated cobalt oxide with 50 wt% copper oxide is shown in Figure 4 (CuO-Co3O4 bar) as measured by X-rite Ci7600. The blackness was measured to be about 160 Mc.

[0119] Example 2 - Copper oxide coated cobalt oxide paint system

[0120] Three inch by five inch aluminum panels coated with black and white coatings were obtained, and the paint system was applied to the panels using an 8-path wet film applicator from Paul N. Gardner Company, Inc. (Pompano Beach, Florida).

[0121] Two grams of Basecoat Balancer ChromaBase 150K and 0.5 grams of the as-prepared pigment were mixed on a vortex mixer for one minute and then sonicated for 30 minutes. The mixture was then transferred to an A-250 mixer and mixed for an additional 10 seconds to form a uniform paste. To prepare the coating, a drawdown was applied to an aluminum panel with an 8 mil (0.20 mm) clearance using an applicator, followed by overnight curing at room temperature. The blackness of the panel was then measured as described above (before the clear coat was applied). The blackness was greater than 156 My and is shown in Figure 8.

[0122] Comparative samples were made by replacing the pigment according to embodiments disclosed and described herein with carbon black, Cool Black, commercially available copper oxide, ball-milled copper oxide (commercially available copper oxide that has been ball-milled to reduce particle size), synthetic copper oxide, and copper oxide mixed with cobalt oxide. The blackness of these comparative samples is also shown in Figure 8. As can be seen, the blackness of the copper oxide-coated cobalt oxide according to embodiments disclosed and described herein is similar to that of carbon black and much higher than that of Cool Black, commercially available copper oxide, ball-milled copper oxide (commercially available copper oxide that has been ball-milled to reduce particle size), synthetic copper oxide, and copper oxide mixed with cobalt oxide.

[0123] To apply the clearcoat, PPG Deltron DC4000 and Deltron DCH 3085 were mixed in a 4:1 ratio on a vortex mixer for 1 minute and then sonicated for 5 minutes. The mixture was then transferred to an A-250 mixer and mixed for an additional 30 seconds to form a uniform, clear liquid. To obtain the clearcoat, a drawdown was applied to the masstone coating using an applicator with an 8 mil (0.20 mm) clearance, followed by curing at room temperature for 10 minutes and at 60°C for 20 minutes. The blackness of the panel was then measured as described above (after application of the clearcoat). The blackness was greater than 132 My and is shown in Figure 9. Comparative samples were also clearcoated, and the blackness of these clearcoated comparative samples was measured. The blackness of these comparative samples is also shown in Figure 9. As can be seen, the blackness of the copper oxide coated cobalt oxide according to the disclosed and described embodiments is similar to that of carbon black and much higher than that of Cool Black, commercial copper oxide, ball milled copper oxide (commercial copper oxide that has been ball milled to reduce particle size), synthetic copper oxide, and copper oxide mixed with cobalt oxide.

[0124] The reflectance of a panel having a clearcoat pigmented with copper oxide-coated cobalt oxide was measured as disclosed herein and is shown in Figure 10. The reflectance of a comparative sample was also measured and is reported in Figure 10. As shown, the reflectance of copper oxide-coated cobalt oxide is approximately the same as carbon black in the visible spectrum, but has significantly higher reflectance than carbon black in the near-IR and LiDAR electromagnetic radiation wavelength ranges. It is also believed that the reflectance of a panel having a clearcoat pigmented with copper oxide-coated cobalt oxide in the near-IR and LiDAR electromagnetic radiation wavelength ranges can be increased by increasing the loading of the copper oxide-coated cobalt oxide pigment in the paint system.

[0125] The LiDAR intensity of a panel having a clearcoat pigmented with copper oxide-coated cobalt oxide was measured as disclosed herein and is shown in Figure 11. The LiDAR intensity of a comparative sample was also measured and is reported in Figure 11. As shown, the LiDAR intensity of the copper oxide-coated cobalt oxide is significantly higher than that of carbon black.

[0126] The above samples and comparative samples demonstrate that pigments formed from copper oxide-coated cobalt oxide have blackness and reflectance in the visible spectrum similar to that of carbon black, the current standard for many black pigment applications (such as automotive paint systems). However, copper oxide-coated cobalt oxide pigments also provide reflectance in the near-IR and LiDAR electromagnetic wavelengths that exceeds that of carbon black. Thus, none of the carbon black, cool black, commercially available copper oxide, ball-milled copper oxide, synthetic copper oxide, or copper oxide mixed with cobalt oxide used in the comparative samples can provide the balance of blackness and reflectance in the near-IR and LiDAR electromagnetic wavelength ranges achieved by the copper oxide-coated cobalt oxide disclosed and described herein.

[0127] Example 3 - Copper Oxide Coated Carbon Black Pigment

[0128] Copper oxide-coated carbon black pigment was produced by a wet chemical method using (NH)CO as a precipitating agent introduced into a solution containing Cu(NO) and carbon black particles. The mass ratio of Cu(NO) to carbon black was 1:3, and the molar ratio of Cu to carbon was 0.07. The precipitating agent was added until a precipitate formed. The formed CuCO coated the carbon black particles. The precipitate was then washed with water and ethanol to remove the (NH)NO. The solution was then filtered to obtain CuCO-coated carbon black particles. The precipitate was dried at 120°C for 12 hours and then calcined at 300°C for 3 hours to form CuO-coated carbon black particles. A scanning electron microscope (SEM) image of the resulting copper oxide-coated carbon black with a CuO:C ratio of 25:75 is shown in Figure 12A. More detailed SEM images shown in Figures 12B and 12C show the antireflection moth-eye structure of the copper oxide coated carbon black with a CuO:C ratio of 25:75.

[0129] The LiDAR intensity of the copper oxide-coated carbon black with a CuO:C ratio of 25:75 prepared as described above was measured using standard carbon black, Cool Black, commercial CuO, a physical mixture of 25:75 CuO and carbon black (CuO mixed with C in FIG. 13), and 25:75 CuO-coated carbon black (CuO deposited on C in FIG. 13) as controls. After applying a clear coat, the LiDAR intensity was measured as described above. The results of this test are shown in FIG. 13. As shown in FIG. 13, the 25:75 CuO-coated carbon black has LiDAR intensity significantly superior to carbon black but lower than Cool Black and commercial CuO. However, Cool Black and commercial CuO do not have a blackness comparable to that of the 25:75 CuO-coated carbon black, as shown in FIG. 4B. Thus, the 25:75 ratio CuO coated carbon black provides a significantly improved balance of LiDAR intensity and blackness that cannot be achieved with either carbon black, cool black, commercial CuO, or physical mixtures of CuO and carbon black.

[0130] Example 4

[0131] To verify the performance of the CuO-coated carbon black disclosed in Example 3 in a dynamic environment, a robot (model TurtleBot 3 Burger) was equipped with a 905 nm 2D laser scanner. This laser scanner can sense 360° and collect a series of data about the robot's surroundings, which can be used for simultaneous localization and mapping (SLAM) and navigation, as well as stopping when an obstacle is detected. A painted panel was placed in front of the autonomously moving robot. When the panel was painted with carbon black, the robot collided with the obstacle without stopping. However, when the panel was painted with the copper oxide-coated carbon black prepared according to Example 3, the robot stopped before colliding with the panel.

[0132] While particular embodiments have been illustrated and described herein, it should be understood that various other changes and modifications can be made without departing from the spirit and scope of the claimed subject matter. Moreover, although various aspects of the claimed subject matter have been described herein, such aspects need not be utilized in combination. It is therefore intended that the appended claims cover all such changes and modifications that are within the scope of the claimed subject matter. Some of the embodiments of the invention related to the present invention are shown below. [Embodiment 1] a particle having an outer surface; a layer of copper oxide on the outer surface of the particle; A copper oxide coated pigment comprising: the copper oxide coated pigment has a reflectance of 5% or less for electromagnetic radiation in the visible spectrum; the copper oxide coated pigment has a reflectance of 5% or greater for electromagnetic radiation in the near IR and LiDAR spectrum; The particles are made of cobalt oxide (Co 3 O 4 ) or carbon black; Copper oxide coated pigment. [Embodiment 2] The particles are cobalt oxide (Co 3 O 4 2. The copper oxide-coated pigment of embodiment 1, wherein [Embodiment 3] 2. The copper oxide-coated pigment of embodiment 1, wherein the particles are carbon black. [Embodiment 4] 2. The copper oxide-coated pigment of embodiment 1, wherein the copper oxide-coated pigment has a reflectance of 2% or less for electromagnetic radiation in the visible spectrum. [Embodiment 5] 2. The copper oxide-coated pigment of embodiment 1, wherein the copper oxide-coated pigment has a reflectance of 20% or greater for electromagnetic radiation in the near-IR and LiDAR spectrum. [Embodiment 6] 2. The copper oxide-coated pigment of embodiment 1, wherein the copper oxide-coated pigment has a reflectance of greater than or equal to 0.5% and less than or equal to 2% for electromagnetic radiation in the visible spectrum. [Embodiment 7] 2. The copper oxide-coated pigment of embodiment 1, wherein the copper oxide-coated pigment has a reflectance of greater than or equal to 10% and less than or equal to 65% for electromagnetic radiation in the near-IR and LiDAR spectrum. [Embodiment 8] 2. The copper oxide-coated pigment of embodiment 1, wherein the copper oxide-coated pigment has a blackness index of 150 or greater and 165 or less. [Embodiment 9] Paint binders and at least one copper oxide-coated pigment according to embodiment 1; and Paint containing. [Embodiment 10] 10. The paint of embodiment 9, wherein the paint has a color with a value of 40 or less in the CIELAB color space. [Embodiment 11] A vehicle having a body panel painted with the paint of embodiment 9. [Embodiment 12] 1. A method for forming copper oxide coated particles, comprising: combining a precipitating agent with a solution containing copper nitrate and particles, thereby forming coated particles, wherein the particles are coated with cobalt oxide (Co 3 O 4 ) or carbon black; washing the particles, thereby obtaining washed coated particles; filtering the washed coated particles to obtain filtered coated particles; drying the filtered coated particles, thereby obtaining dried coated particles; and calcining the dried coated particles to form copper oxide coated particles; A method comprising: [Embodiment 13] 13. The method of embodiment 12, wherein the precipitating agent is selected from the group consisting of sodium hydroxide, sodium carbonate, and ammonium carbonate. [Embodiment 14] 14. The method of embodiment 13, wherein the precipitating agent is ammonium carbonate. [Embodiment 15] The particles are cobalt oxide (Co 3 O 4 13. The method of embodiment 12, wherein [Embodiment 16] 13. The method of embodiment 12, wherein the particles are carbon black particles. [Embodiment 17] 13. The method of embodiment 12, wherein the coated particles comprise copper nitrate-coated particles, copper hydroxide-coated particles, or copper carbonate-coated particles. [Embodiment 18] 13. The method of embodiment 12, wherein washing the coated particles comprises washing the coated particles in a mixture of ethanol and water. [Embodiment 19] 16. The method of embodiment 15, wherein drying the filtered coated particles comprises drying the filtered coated particles at a temperature of at least 100°C and not more than 140°C for a time period of at least 0.5 hours and not more than 5.0 hours. [Embodiment 20] 20. The method of embodiment 19, wherein calcining the dried coated particles comprises calcining the dried coated particles at a temperature of from 430°C to 470°C for a time period of from 0.5 to 5.0 hours. [Embodiment 21] 17. The method of embodiment 16, wherein drying the filtered coated particles comprises drying the filtered coated particles at a temperature of at least 100°C and not more than 140°C for a time period of at least 5 hours and not more than 15 hours. [Embodiment 22] 22. The method of embodiment 21, wherein calcining the dried coated particles comprises calcining the dried coated particles at a temperature of at least 200°C and at most 300°C for a time period of at least 0.5 hours and at most 5.0 hours. [Embodiment 23] 1. A method for forming copper oxide-coated cobalt oxide particles, comprising: combining a sodium carbonate precipitant with a solution containing copper nitrate and cobalt nitrate, thereby forming coated cobalt oxide particles; washing the coated cobalt oxide particles, thereby obtaining washed coated cobalt oxide particles; filtering the washed coated cobalt oxide particles, thereby obtaining filtered coated cobalt oxide particles; drying the filtered coated cobalt oxide particles, thereby obtaining dried coated cobalt oxide particles; and calcining the dried coated cobalt oxide particles to form copper oxide-coated cobalt oxide particles; A method comprising: [Embodiment 24] 24. The method of embodiment 23, wherein the coated cobalt oxide particles comprise copper nitrate coated cobalt oxide. [Embodiment 25] 24. The method of embodiment 23, wherein drying the filtered coated cobalt oxide particles comprises drying the filtered coated cobalt oxide particles at a temperature of at least 100°C and not more than 140°C for a time period of at least 0.5 hours and not more than 5.0 hours. [Embodiment 26] 24. The method of embodiment 23, wherein calcining the dried coated cobalt oxide particles comprises calcining the dried coated cobalt oxide particles at a temperature of from 430° C. to 470° C. for a time period of from 0.5 to 5.0 hours.

Claims

1. a particle having an outer surface; a layer of copper oxide on the outer surface of the particle; A copper oxide coated pigment comprising: the copper oxide coated pigment has a reflectance of 5% or less for electromagnetic radiation in the visible spectrum; the copper oxide coated pigment has a reflectance of 5% or greater for electromagnetic radiation in the near-IR and LiDAR spectrum; The particles are made of cobalt oxide (Co 3 O 4 ) or carbon black; Copper oxide coated pigment.

2. The particles are made of cobalt oxide (Co 3 O 4 2. The copper oxide-coated pigment according to claim 1, wherein

3. 2. The copper oxide coated pigment of claim 1, wherein the particles are carbon black.

4. 10. The copper oxide-coated pigment of claim 1, wherein the copper oxide-coated pigment has a reflectance of 2% or less for electromagnetic radiation in the visible spectrum.

5. 10. The copper oxide-coated pigment of claim 1, wherein the copper oxide-coated pigment has a reflectance of 20% or greater for electromagnetic radiation in the near-IR and LiDAR spectrum.

6. 2. The copper oxide-coated pigment of claim 1, wherein the copper oxide-coated pigment has a reflectance of 0.5% or greater and 2% or less for electromagnetic radiation in the visible spectrum.

7. 10. The copper oxide-coated pigment of claim 1, wherein the copper oxide-coated pigment has a reflectance of 10% or greater and 65% or less for electromagnetic radiation in the near-IR and LiDAR spectrum.

8. 2. The copper oxide-coated pigment according to claim 1, wherein the copper oxide-coated pigment has a blackness of 150 or greater and 165 or less.

9. Paint binders and At least one copper oxide-coated pigment according to claim 1; Paint containing.

10. 10. The paint of claim 9, wherein the paint has a color with a value of 40 or less in the CIELAB color space.

11. A vehicle having a body panel painted with the paint of claim 9.

12. 1. A method for forming copper oxide coated particles, comprising: combining a precipitating agent with a solution containing copper nitrate and particles, thereby forming coated particles, wherein the particles are coated with cobalt oxide (Co 3 O 4 ) or carbon black; washing the coated particles, thereby obtaining washed coated particles; filtering the washed coated particles to obtain filtered coated particles; drying the filtered coated particles, thereby obtaining dried coated particles; and calcining the dried coated particles to form copper oxide coated particles; Including, The method wherein the precipitating agent is selected from the group consisting of sodium hydroxide, sodium carbonate, and ammonium carbonate.

13. 13. The method of claim 12, wherein the precipitating agent is ammonium carbonate.

14. The particles are cobalt oxide (Co 3 O 4 13. The method of claim 12, wherein

15. The method of claim 12 wherein the particles are carbon black particles.

16. 13. The method of claim 12, wherein the coated particles comprise copper nitrate coated particles, copper hydroxide coated particles, or copper carbonate coated particles.

17. The method of claim 12 , wherein washing the coated particles comprises washing the coated particles in a mixture of ethanol and water.

18. 15. The method of claim 14, wherein drying the filtered coated particles comprises drying the filtered coated particles at a temperature of at least 100°C and at most 140°C for a time period of at least 0.5 hours and at most 5.0 hours.

19. 20. The method of claim 18, wherein calcining the dried coated particles comprises calcining the dried coated particles at a temperature of from 430°C to 470°C for a time period of from 0.5 hours to 5.0 hours.

20. 16. The method of claim 15, wherein drying the filtered coated particles comprises drying the filtered coated particles at a temperature of at least 100°C and at most 140°C for a time period of at least 5 hours and at most 15 hours.

21. 21. The method of claim 20, wherein calcining the dried coated particles comprises calcining the dried coated particles at a temperature of from 200°C to 300°C for a time period of from 0.5 hours to 5.0 hours.

22. 1. A method for forming copper oxide-coated cobalt oxide particles, comprising: combining a sodium carbonate precipitant with a solution containing copper nitrate and cobalt nitrate, thereby forming coated cobalt oxide particles; washing the coated cobalt oxide particles, thereby obtaining washed coated cobalt oxide particles; filtering the washed coated cobalt oxide particles, thereby obtaining filtered coated cobalt oxide particles; drying the filtered coated cobalt oxide particles, thereby obtaining dried coated cobalt oxide particles; and calcining the dried coated cobalt oxide particles to form copper oxide-coated cobalt oxide particles; A method comprising:

23. 23. The method of claim 22, wherein the coated cobalt oxide particles comprise copper nitrate coated cobalt oxide.

24. 23. The method of claim 22, wherein drying the filtered coated cobalt oxide particles comprises drying the filtered coated cobalt oxide particles at a temperature of at least 100°C and at most 140°C for a time period of at least 0.5 hours and at most 5.0 hours.

25. 23. The method of claim 22, wherein calcining the dried coated cobalt oxide particles comprises calcining the dried coated cobalt oxide particles at a temperature of at least 430°C and at most 470°C for a time period of at least 0.5 hours and at most 5.0 hours.

Images