Catalytic Pt nanodots formed by pulsed / continuous CVD or atomic layer deposition

Abstract

The present disclosure describes a method for depositing a plurality of Pt metal-containing nanodots on a catalyst carbon support structure by forming a vapor of Pt(PF3)4, exposing the surface of the catalyst support to the vapor of Pt(PF3)4, purging the surface of the catalyst support with a purge gas to remove the vapor of Pt(PF3)4, exposing the surface of the catalyst support to a second reactant in gas form, purging the surface of the catalyst support with a purge gas to remove the second reactant, and repeating these steps to form a plurality of Pt metal-containing nanodots.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 072,562, filed on August 31, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The catalyst Pt nanodots were formed by pulsed / continuous CVD or atomic layer deposition. Background Art

[0004] Prior art is described in Van Bui, H., F. Grillo and JRVan Ommen. "Atomic and molecular layer deposition: off the beaten track." Chemical Communications 53.1 (2017): 45-71 (reference numbers omitted):

[0005] The development of Pt ALD began in 2003 with the seminal work of Aaltonen et al., who demonstrated thermal ALD of Pt thin films using methylcyclopentadienyl-(trimethyl)platinum (MeCpPtMe3) as a Pt precursor and O2 as a co-reactant. To date, this remains the most commonly used ALD method for growing both Pt thin films and nanoparticles on a wide range of substrates, such as flat surfaces, nanowires, nanoparticles, and carbon nanomaterials. Given the potential applications of Pt ALD, several research groups have conducted fundamental studies aimed at elucidating the surface chemistry behind the formation of metallic Pt. These studies have shown that the surface chemistry depends on the oxidation reactions of MeCpPtMe3 and O2 exposure. It is believed that the chemisorption of MeCpPtMe3 occurs via partial oxidation of the organic ligands by adsorbed reactive oxygen species on the substrate surface. This reaction then reaches saturation after the available reactive surface oxygen is consumed. The role of the oxidation step via O2 is therefore twofold: oxidation of the remaining ligands and restoration of the adsorbed oxygen layer, which is necessary for the subsequent chemisorption of MeCpPtMe3. These studies also indicate that oxygen dissociates on the platinum surface, forming a persistent monoatomic oxygen layer, which is particularly active for the combustion of the organic ligands of MeCpPtMe3. The ALD window typically reported for this surface chemistry is 200°C-350°C. Specifically, 200°C has been widely accepted as the lower temperature limit, although growth at slightly lower temperatures (i.e., 175°C) has recently been obtained. This lower limit is attributed to the low reactivity of oxygen for ligand combustion at temperatures below 200°C. Such high deposition temperatures make thermal methods unsuitable for heat-sensitive substrates. In addition, when used for the deposition of NPs, high temperatures are undesirable because they may promote sintering and therefore limit the ability to control NP size. In order to avoid this limitation, the use of plasma and ozone has been explored. However, plasma methods are mainly suitable for the deposition of Pt films and NPs on flat substrates, and their application on substrates with complex geometries such as powders is still limited.

[0006] As discussed in the aforementioned review article, prior art approaches to plasma-enhanced deposition have not yet been successfully used to reduce the deposition temperature on cathode carbon supports for catalytic Pt nanodots. To date, the art still lacks a Pt deposition scheme for cathode carbon supports that achieves sufficient nanodot formation without excessive Pt oxide formation to meet the practical needs of fuel cells for vehicles, particularly those using polymer electrolyte membrane designs. Summary of the Invention

[0007] The present invention may be understood with reference to the following non-limiting, exemplary embodiments described as follows:

[0008] 1. A method for depositing Pt metal nanodots on a catalyst support structure, preferably a catalyst carbon support structure, comprising the following steps:

[0009] a. Formation of Pt(PF3)4 vapor,

[0010] b. exposing the surface of the catalyst support structure to the vapor of Pt(PF3)4,

[0011] c. purging the surface of the catalyst support structure with a purge gas to remove the Pt(PF3)4 vapor,

[0012] d. exposing the surface of the catalyst structure to a second reactant in gaseous form,

[0013] e. purging the surface of the catalyst support structure with a purge gas to remove the second reactant,

[0014] f. Repeating steps a.-e. to form a plurality of Pt metal-containing nanodots on the catalyst support structure,

[0015] Wherein the temperature of the catalyst support structure during step a. and / or step b. is from 50°C to 300°C, preferably from 100°C to less than 200°C, more preferably 100°C to 175°C or to less than 175°C, such as 100°C or 150°C.

[0016] 2. The method of claim 1, wherein the second reactant comprises an oxidant selected from the group consisting of H2O, O2, O3, oxygen radicals, and mixtures thereof; preferably O2.

[0017] 3. The method of claim 1, wherein the second reactant comprises a reducing agent selected from the group consisting of H2, NH3, SiH4, Si2H6, Si3H8, SiH2Me2, SiH2Et2, N(SiH3)3, hydrogen radical, hydrazine, methylhydrazine, amines, and mixtures thereof; preferably H2.

[0018] 4. The method of claim 1, wherein the second reactant is selected from the group consisting of H2, O2, and combinations thereof.

[0019] 5. The method of any one of statements 1-4, wherein steps a.-e. are repeated 5-20 times.

[0020] 6. The method of any one of statements 1-5, wherein the plurality of Pt metal-containing nanodots are formed by an atomic layer deposition reaction.

[0021] 7. The method of any one of clauses 1-6, wherein a maximum linear dimension of the nanodots has a range from 0.25 nm to 15 nm and / or an average value of 2 nm-7 nm.

[0022] 8. The method of any one of clauses 1 to 7, wherein the catalyst support structure comprises a plurality of discrete particles having an outer surface, and after step f. the discrete particles have a coverage of Pt metal-containing nanodots of at least 1 nanodot / nm 2 The average surface area of the particles.

[0023] 9. The method of any one of statements 1-8, wherein each nanodot contains sufficient Pt such that a) the atomic percentage of Pt of the catalyst support structure having the plurality of Pt-containing nanodots is from 0.5% to 3%, preferably 1% to 2%, and / or b) the weight percentage of Pt is from 5% to 50%, preferably 10% to 30%.

[0024] 10. The method of any one of statements 1-9, wherein the catalyst support structure is a catalyst carbon support structure.

[0025] 11. The method of clause 10, wherein the plurality of Pt nanodots are formed directly on the carbon component of the catalytic carbon support.

[0026] 12. The method of claim 10 or 11, wherein the catalyst carbon support structure is a single-walled fullerene such as C 60 and C 72 , multi-walled fullerenes, single-walled or multi-walled nanotubes, nanohorns, and / or having a density of about 0.2 g / cm3 to about 1.9 g / cm3, such as specialty carbons like VULCAN or Imerys' SUPER C65.

[0027] 13. The method of any one of statements 1-12, further comprising the step of exposing the surface of the catalyst structure to a third reactant in gaseous form, wherein if the second reactant is an oxidizing agent, the third reactant is a reducing agent, and vice versa.

[0028] 14. The method of claim 13, wherein the step of exposing the surface of the catalyst structure to the third reactant is separated from step d. by step e.

[0029] 15. The method of claim 14, wherein the second reactant is oxygen and the third reactant is hydrogen.

[0030] 16. A method for depositing Pt metal-containing nanodots on a catalyst support structure, preferably a catalyst carbon support structure, the method comprising the following steps:

[0031] a. Formation of Pt(PF3)4 vapor,

[0032] b. exposing the surface of the catalyst support structure to the vapor of Pt(PF3)4,

[0033] wherein step b. lasts for a time sufficient to form a plurality of Pt metal-containing nanodots on the catalyst support structure,

[0034] wherein the catalyst support structure is not exposed to any additional reactants to form the plurality of Pt metal-containing nanodots on the catalyst support structure, and

[0035] Wherein the temperature of the surface of the catalyst support structure during step a. and / or step b. is from 50°C to 300°C, preferably from 100°C to less than 200°C, more preferably 100°C to 175°C or to less than 175°C, such as 100°C or 150°C.

[0036] 17. The method of clause 16, wherein the largest linear dimension of the nanodots has a range from 0.25 nm to 15 nm and / or an average value of 2 nm-7 nm.

[0037] 18. The method of clause 16 or 17, wherein the catalyst support structure comprises a plurality of discrete particles having an outer surface, and after step b. the discrete particles have a coverage of Pt metal-containing nanodots of at least 1 nanodot / nm 2 The average surface area of the particles.

[0038] 19. The method of any one of statements 16-18, wherein each nanodot contains sufficient Pt such that a) the atomic percentage of Pt of the catalyst support structure having the plurality of Pt-containing nanodots is from 0.5% to 3%, preferably 1% to 2%, and / or b) the weight percentage of Pt is from 5% to 40%, preferably 10% to 30%.

[0039] 20. The method of any one of statements 16-19, wherein the catalyst support structure is a catalyst carbon support structure.

[0040] 21. The method of clause 20, wherein the plurality of Pt nanodots are formed directly on the carbon component of the catalytic carbon support.

[0041] 22. The method of claim 20 or 21, wherein the catalyst carbon support structure is a single-walled fullerene such as C 60 and C72 , multi-walled fullerenes, single-walled or multi-walled nanotubes, nanohorns, and / or having a density of about 0.2 g / cm3 to about 1.9 g / cm3, such as specialty carbons like VULCAN or Ingceramics' SUPER C65.

[0042] 23. A method for depositing Pt metal-containing nanodots on a catalyst support structure, preferably a catalyst carbon support structure, the method comprising the following steps:

[0043] a. Formation of Pt(PF3)4 vapor,

[0044] b. exposing the surface of the catalyst support structure to the Pt(PF3)4 vapor and the oxidant simultaneously,

[0045] wherein step b. lasts for a time sufficient to form a plurality of Pt metal-containing nanodots on the catalyst support structure,

[0046] wherein the catalyst support structure is not exposed to any additional reactants to form the plurality of Pt metal-containing nanodots on the catalyst support structure, and

[0047] Wherein the temperature of the surface of the catalyst support structure during step a. and / or step b. is from 50°C to 300°C, preferably from 100°C to less than 200°C, more preferably 100°C to 175°C or to less than 175°C, such as 100°C or 150°C.

[0048] 24. The method of claim 23, wherein the oxidant is selected from the group consisting of H2O, O2, O3, oxygen radicals, and mixtures thereof; preferably O2.

[0049] 25. The method of clause 23 or 24, wherein the largest linear dimension of the nanodots has a range from 0.25 nm to 15 nm and / or an average value of 2 nm-7 nm.

[0050] 26. The method of any one of clauses 23-25, wherein the catalyst support structure comprises a plurality of discrete particles having an outer surface, and after step b. the discrete particles have a coverage of Pt metal-containing nanodots of at least 1 nanodot / nm 2 The average surface area of the particles.

[0051] 27. A method as described in any of statements 23-26, wherein each nanodot contains sufficient Pt such that a) the atomic percentage of Pt of the catalyst support structure having the plurality of Pt-containing nanodots is from 0.5% to 3%, preferably 1% to 2%, and / or b) the weight percentage of Pt is from 5% to 40%, preferably 10% to 30%.

[0052] 28. The method of any one of statements 23-27, wherein the catalyst support structure is a catalyst carbon support structure.

[0053] 29. The method of clause 28, wherein the plurality of Pt nanodots are formed directly on the carbon component of the catalytic carbon support.

[0054] 30. The method of claim 28 or 29, wherein the catalyst carbon support structure is a single-walled fullerene such as C 60 and C 72 , multi-walled fullerenes, single-walled or multi-walled nanotubes, nanohorns, and / or having a density of about 0.2 g / cm3 to about 1.9 g / cm3, such as specialty carbons like VULCAN or Ingceramics' SUPER C65.

[0055] 31. The method of any of the preceding statements, wherein the plurality of Pt nanodots comprises face-centered cubic Pt crystals.

[0056] 32. The method of any of the preceding sentences, wherein the utilization efficiency is from 30 weight percent to 99 weight percent, preferably at least 50 weight percent, more preferably at least 75 weight percent, such as 50 weight percent to 90 weight percent or 75 weight percent to 80 weight percent. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 The vapor pressure of MeCpPtMe3 (lower line) and Pt(PF3)4 (upper line) is shown versus temperature;

[0058] Figure 2 shows the powder vapor deposition apparatus used to expose C65 powder to Pt(PF3)4 in the experiments described herein;

[0059] Figure 3 Deposition of Pt nanodots on C65 by CVD with hydrogen as co-reactant (replicating prior art) is shown. XPS data are presented as X-axis = normalized intensity (arbitrary units) and Y-axis = eV;

[0060] Figure 4 Deposition of Pt nanodots on C65 by ALD with hydrogen as co-reactant is shown. XPS data are presented as X-axis = normalized intensity (arbitrary units) and Y-axis = eV. Vertical lines indicate Pt 0 eV. Most Pt is deposited at 100 °C and most Pt 0 Deposition at 150°C;

[0061] Figure 5shows that for 100°C deposition from Figure 4 Scanning electron microscope (SEM) image of experimental C65;

[0062] Figure 6 Representative results from thermal decomposition deposition in the absence of hydrogen are shown. XPS data are presented as X-axis = normalized intensity (arbitrary units) and Y-axis = eV. Vertical bars indicate Pt 0 eV. The amount of Pt nanodots increases with each temperature increase. However, Pt is almost completely oxidized at all temperatures;

[0063] Figure 7 Representative results for oxygen CVD are shown. XPS data are presented as X-axis = normalized intensity (arbitrary units) and Y-axis = eV. Vertical bars indicate Pt 0 eV. Pt nanodot deposition increases with temperature up to 150°C and then decreases at 200°C to the level of the reaction at about 100°C. All conditions have a large amount of oxidized Pt, but the 150°C deposition produces the most Pt 0 ;

[0064] Figure 8 It is shown that oxygen as a co-reactant in continuous exposure (e.g., ALD) produces more Pt nanodots on C65. XPS data are presented as X-axis = normalized intensity (arbitrary units) and Y-axis = eV. The vertical line indicates Pt 0 eV. The amount of Pt and its Pt 0 The fraction of forms all increased with temperature from 50 to 150 °C, with 200 °C having results comparable to 150 °C;

[0065] Figure 9 shows that for 100°C deposition from Figure 8 Scanning electron microscope (SEM) image of experimental C65. DETAILED DESCRIPTION

[0066] "Nanodots" means, for example, discrete deposits of Pt having a largest cross-sectional dimension from 1 nm to 100 nm. Nanodots are most typically roughly hemispherical or roughly circular, but can be any shape, including irregularly shaped morphologies.

[0067] "Catalyst support structure" refers to a material used to support a catalytic material such as Pt nanodots in the cathode of a lithium-ion battery. See, for example, Ye, Siyu, Miho Hall, and Ping He. "PEM fuel cell catalysts: the importance of catalyst support." ECS Transactions 16.2 (2008): 2101; Shao, Yuyan et al. "Novel catalyst support materials for PEM fuel cells: current status and future prospects." Journal of Materials Chemistry 19.1 (2009): 46-59.

[0068] "Catalyst carbon support structure" means a catalyst support structure having carbon as a component. Examples include carbon black, graphite, graphene, C 60 ("buckyballs", "fullerenes"), C 72 (Ma, Jian-Li et al. "C 72 :A novel low energy and direct band gap carbon phase.[C 72 : A new low-energy and direct-bandgap carbon phase]" Physics Letters A [Physics Letters A] (2020): 126325), carbon-walled nanotubes (including multi-walled nanotubes), carbon nanofibers and silicon-mesoporous carbon composites such as C65.

[0069] "C65" means a catalyst carbon support structure having a silicon-mesoporous carbon composite material, such as those described in Spahr, Michael E. et al. "Development of carbon conductive additives for advanced lithium ion batteries." Journal of Power Sources 196.7 (2011): 3404-3413.

[0070] Tetrakis(trifluorophosphine)platinum (Pt(PF3)4) is a known chemical substance (CAS#19529-53-4). Figure 1As shown, Pt(PF3)4 has a much higher vapor pressure than the current platinum deposition precursor Pt(MeCp)Me3.

[0071] Previous work on Pt(PF3)4 describes its use as a CVD precursor for thin film deposition. Rand, Myron J. "Chemical Vapor Deposition of Thin-Film Platinum." Journal of The Electrochemical Society 120.5 (1973): 686-693. Previous work focused on thermal CVD for Pt thin film deposition. The operable temperature range was determined to be greater than 175°C, and specifically 200°C to 300°C, to form metallic Pt as the primary Pt component of the film. Lower temperatures resulted in incomplete pyrolysis and poorer film quality. Oxidizing environments are avoided, and even nitrogen has a negative effect on film quality.

[0072] We repeated and verified the foregoing. H2CVD at 50°C, 100°C, 150°C, and even 200°C produced negligible Pt nanodot formation on C65 substrates (discussed in the experimental section below). The small amount of Pt deposited was mostly oxidized. Therefore, the prior art and our own results indicate that Pt(PF3)4 is not a candidate for low-temperature Pt nanodot deposition. Thus, our subsequent work demonstrating successful deposition conditions was highly unexpected and surprising.

[0073] General conditions for Pt nanodot deposition using Pt(PF3)4

[0074] The target substrate for Pt nanodot deposition is conductive carbon black C-NERGY TM Super C65. Spahr, Michael E. et al. "Development of carbon conductive additives for advanced lithium ion batteries." Journal of Power Sources 196.7 (2011): 3404-3413.

[0075] exist Figure 2 Unless otherwise indicated, all Pt nanodot depositions were performed under the following conditions:

[0076] Pt precursor (provided by MFC)

[0077] Pt(PF3)4 flow rate: actual about 0.56 sccm (N2 MFC is 2 sccm)

[0078] Tank T: 30℃

[0079] Tank P: VP of PPF

[0080] Co-reactant O2 or H2 flow rate: 10sccm

[0081] Pressurize N2 35sccm

[0082] Reactor pressure: 10 Torr

[0083] Supporting base (carbon support): C-NERGY super C65: 1 gram (8 mm stainless steel balls were packed together with the carbon powder to prevent agglomeration).

[0084] XRD and XPS reference data were collected from pure C65, Pt metal foil, and C65+Pt metal mesh. XRD patterns corresponding to Pt patterns and C patterns were observed at 100°C, 150°C, 175°C, and 200°C, indicating that metallic platinum can be formed under these conditions. Based on the reference material, XPS Pt4f 7 / 2 The peak position is 71.2 eV (corresponding to Pt 0 ), and the peak position of C1 is 284.6 eV. XPS data are presented as X-axis = normalized intensity (arbitrary units) and Y-axis = eV.

[0085] Comparative Example: Pt(PF3)4CVD with Hydrogen

[0086] CVD was performed using the above conditions at 50°C, 100°C, 150°C, and 200°C for 2400 seconds. Representative XPS data are available at Figure 3 As expected based on the prior art, very little Pt was deposited under these conditions, even at 200°C (the maximum for this series of experiments), and the resulting Pt was largely oxidized. Thus, it was confirmed that at 200°C or below, in addition to thin film deposition, the prior art deposition methods are not suitable for Pt nanodot deposition.

[0087] Continuous deposition or atomic layer deposition of Pt(PF3)4 using hydrogen

[0088] In direct comparison to CVD results, alternating the delivery of Pt(PF3)4 and hydrogen into separate substrate exposure steps (such as atomic layer deposition methods) produces significantly different and surprising results. Representative results from ALD deposition with hydrogen are given in Figure 4(ALD cycle number: 12; ALD sequence: PPF 200s; purge 600s; H2 500s; purge 600s; 100°C, 150°C and 200°C). Figure 3 There is a clear and significant improvement in Pt deposition compared to , and this is sufficient to make Pt nanodot deposition feasible. Most of the Pt is metallic (indicated by the vertical lines ----) rather than oxidized (indicated by the lines -----), which is also preferred for catalytic materials. Figure 5 shows that for 150°C deposition from Figure 4 Scanning electron microscope (SEM) images of C65. Notably, the amount of deposited Pt actually decreases at 200°C, indicating that, contrary to prior art conclusions for Pt thin film deposition, the optimal temperature for Pt nanodot deposition is >100°C to <200°C. This result, along with the oxygen deposition results, demonstrates that, unexpectedly, there is no clear correlation between prior art Pt thin film deposition and Pt nanodot deposition on catalyst support structures or materials.

[0089] We performed additional analysis of the deposited Pt nanodots in air, specifically powder X-ray diffraction, differential thermal analysis, and thermogravimetric analysis. XRD results indicated that the metallic Pt deposited at 150°C was crystalline, with a face-centered cubic (FCC) structure. FCC-crystalline Pt, rather than amorphous Pt, is the preferred form of catalytically active metallic Pt.

[0090] For industrialization, the amount of metallic Pt deposited onto the catalytic support and its stability are important factors. TGA+DTA analysis showed that Pt nanodots formed at 150°C were thermally stable up to approximately 575°C. TGA analysis of the final residual mass at 1000°C revealed that approximately 9 weight percent of the material was deposited Pt. By varying the number of cycles, pulse length, and temperature, Pt concentrations of 30 weight percent (or higher) were achieved, with the best results achieved at 150°C among the temperatures tested.

[0091] Utilization efficiency means [amount of Pt deposited on the catalytic support] / [amount of Pt introduced as Pt(PF3)4] and can be expressed as a fraction or as a percentage. By varying the number of cycles, pulse length, and temperature, Pt utilization efficiencies of 75% (or higher) were achieved, with the best results at 150°C among the temperatures tested.

[0092] Pt(PF3)4 deposition without co-reactant (thermal decomposition)

[0093] In view of the unexpected and counter-intuitive results with alternating Pt(PF3)4 and hydrogen delivery, we investigated a pure thermal decomposition CVD method (2400 s reaction time; 50°C, 100°C, 150°C and 200°C) without any co-reactants. Representative results from thermal decomposition deposition without hydrogen are given in Figure 6 The SEM of C65 sample shows the same Figure 5 Pt nanodots similar to those seen in .

[0094] Pt(PF3)4: CVD deposition with oxygen; continuous deposition or atomic layer deposition with oxygen

[0095] Given the unexpected and surprising Pt nanodot deposition observed without a co-reactant and with an alternating hydrogen co-reactant, we explored the use of oxygen as a representative oxidizing co-reactant. Based on prior art, oxygen is incompatible with Pt film deposition using Pt(PF3)4. By replacing hydrogen with oxygen (but keeping the conditions otherwise identical), we determined that oxygen is not only compatible with Pt nanodot deposition, but also performs better than hydrogen in some respects.

[0096] Figure 7 Representative results of oxygen CVD are shown. Figure 3 The results shown in the case of hydrogen, oxygen co-reactant CVD produced significantly more Pt nanodots on C65 (SEM not shown). Similarly, oxygen as a co-reactant in a continuous exposure (such as ALD) produced more Pt nanodots on C65 ( Figure 8 ). Representative SEM images of Pt nanodots formed at 100°C are shown in Figure 9 Shown in.

[0097] Preferred Pt nanodot deposition

[0098] Compared to prior art Pt film deposition, Pt nanodot deposition occurs at temperatures below 200°C, preferably at or below 175°C, such as 150°C, 100°C, and even at 50°C (to a lesser extent). Based on the thermal tolerance of current catalyst substrate materials such as C65, the industry needs deposition, especially for temperatures of 175°C or lower. Although we have demonstrated robust Pt nanodot deposition at low temperatures, the preferred Pt state is metallic Pt rather than oxidized Pt. Therefore, conditions that favor the metallic Pt content in the Pt nanodots are preferred. Additional parameter optimization is expected to further improve these results. One exemplary optimization is to use continuous oxygen and then hydrogen co-reactant deposition to produce a mixed result of their relative benefits while mitigating their relatively undesirable characteristics. For example, oxygen (or any oxidant) can be used for most of the ALD cycle, followed by a hydrogen (or any other reducing agent) ALD cycle.

Claims

1. A method for depositing Pt-containing nanodots on a catalyst support structure, the method comprising the following steps: a. Formation of Pt(PF3)4 vapor, b. exposing the surface of the catalyst support structure to the vapor of Pt(PF3)4, c. purging the surface of the catalyst support structure with a purge gas to remove the Pt(PF3)4 vapor, d. exposing the surface of the catalyst support structure to a second reactant in gaseous form, e. purging the surface of the catalyst support structure with a purge gas to remove the second reactant, f. Repeating steps a.-e. to form a plurality of Pt-containing nanodots on the catalyst support structure, wherein the temperature of the catalyst support structure during step a. and / or step b. is from 50°C to 300°C.

2. The method according to claim 1, wherein The catalyst support structure is a catalyst carbon support structure.

3. The method according to claim 1, wherein The temperature of the catalyst support structure during step a. and / or step b. is from 100°C to less than 200°C.

4. The method according to claim 3, wherein: The temperature of the catalyst support structure during step a. and / or step b. is from 100°C to 175°C.

5. The method according to claim 4, wherein: The temperature of the catalyst support structure during step a. and / or step b. is from 100°C to less than 175°C.

6. The method according to claim 5, wherein: The temperature of the catalyst support structure during step a. and / or step b. is from 100°C to 150°C.

7. The method of claim 1, wherein: The second reactant comprises an oxidant selected from the group consisting of H2O, O2, O3, NO2, oxygen radicals, and mixtures thereof.

8. The method of claim 7, wherein: The oxidant is O2.

9. The method of claim 1, wherein: The second reactant comprises a reducing agent selected from the group consisting of: H2, NH3, SiH4, Si2H6, Si3H8, SiH2Me2, SiH2Et2, N(SiH3)3, hydrogen radical, hydrazine, methylhydrazine, amine, NO, N2O and mixtures thereof.

10. The method of claim 9, wherein: The reducing agent is H2.

11. The method according to claim 7, wherein: The catalyst support structure is not exposed to any additional reactants to form the plurality of Pt-containing nanodots on the catalyst support structure.

12. The method of claim 1, wherein: The maximum linear dimensions of these nanodots are: 1) in the range of 0.25 nm to 15 nm; and / or 2) Average value of 2nm-7nm.

13. The method of claim 7, wherein: The maximum linear dimensions of these nanodots are: 1) in the range of 0.25 nm to 15 nm; and / or 2) Average value of 2nm-7nm.

14. The method of claim 1, wherein: Each Pt-containing nanodot contains sufficient Pt such that a) the atomic percentage of Pt of the catalyst support structure having the plurality of Pt-containing nanodots is from 0.5% to 3%, and / or b) the weight percentage of Pt is from 5% to 50%.

15. The method of claim 7, wherein: Each Pt-containing nanodot contains sufficient Pt such that a) the atomic percentage of Pt of the catalyst support structure having the plurality of Pt-containing nanodots is from 0.5% to 3%, and / or b) the weight percentage of Pt is from 5% to 50%.

16. The method of claim 14, wherein: a) the atomic percentage of Pt in the catalytic carbon support structure having the plurality of Pt-containing nanodots is from 1% to 2%, and / or b) the weight percentage of Pt is from 10% to 30%.

17. The method of claim 15, wherein: a) the atomic percentage of Pt in the catalytic carbon support structure having the plurality of Pt-containing nanodots is from 1% to 2%, and / or b) the weight percentage of Pt is from 10% to 30%.

18. The method of claim 1, wherein: The catalyst support structure is a catalyst carbon support structure containing at least 30% by weight carbon.

19. The method of claim 7, wherein: The catalyst support structure is a catalyst carbon support structure containing at least 30% by weight carbon.

20. The method of claim 18, wherein: The plurality of Pt-containing nanodots are formed directly on the carbon component of the catalyst carbon support structure.

21. The method of claim 19, wherein: The plurality of Pt-containing nanodots are formed directly on the carbon component of the catalyst carbon support structure.

22. A method for depositing Pt-containing nanodots on a catalyst support structure, the method comprising the following steps: a. Formation of Pt(PF3)4 vapor, b. exposing the surface of the catalyst support structure to the vapor of Pt(PF3)4, wherein step b. lasts for a time sufficient to form a plurality of Pt-containing nanodots on the catalyst support structure, wherein the catalyst support structure is not exposed to any additional reactants to form the plurality of Pt-containing nanodots on the catalyst support structure, and wherein the temperature of the surface of the catalyst support structure during step a. and / or step b. is from 50° C. to 300° C., Wherein, the catalyst support structure is a catalyst carbon support structure containing at least 30% by weight of carbon.

23. The method of claim 22, wherein: The catalyst support structure is a catalyst carbon support structure.

24. The method of claim 22, wherein: The temperature of the catalyst support structure during step a. and / or step b. is from 100°C to less than 200°C.

25. The method of claim 24, wherein: The temperature of the catalyst support structure during step a. and / or step b. is from 100°C to 175°C.

26. The method of claim 25, wherein: The temperature of the catalyst support structure during step a. and / or step b. is from 100°C to less than 175°C.

27. The method of claim 26, wherein: The temperature of the catalyst support structure during step a. and / or step b. is from 100°C to 150°C.

28. The method of claim 22, wherein: The maximum linear dimensions of these Pt-containing nanodots are: 1) in the range of 0.25 nm to 15 nm; and / or 2) Average value of 2nm-7nm.

29. The method of claim 22, wherein: Each nanodot contains sufficient Pt such that a) the atomic percentage of Pt of the catalyst support structure having the plurality of Pt-containing metal nanodots is from 0.5% to 3%, and / or b) the weight percentage of Pt is from 5% to 50%.

30. The method of claim 28, wherein Each nanodot contains sufficient Pt such that a) the atomic percentage of Pt of the catalyst support structure having the plurality of Pt-containing metal nanodots is from 0.5% to 3%, and / or b) the weight percentage of Pt is from 5% to 50%.

31. The method of claim 29, wherein: a) the atomic percentage of Pt of the catalyst support structure having the plurality of Pt-containing nanodots is from 1% to 2%, and / or b) the weight percentage of Pt is from 10% to 30%.

32. The method of claim 30, wherein: a) the atomic percentage of Pt of the catalyst support structure having the plurality of Pt-containing nanodots is from 1% to 2%, and / or b) the weight percentage of Pt is from 10% to 30%.

33. The method of claim 22, wherein: The plurality of Pt-containing nanodots are formed directly on the carbon component of the catalyst carbon support.

34. A method as claimed in any one of the preceding claims, wherein The utilization efficiency is from 30 weight percent to 99 weight percent.

35. The method of claim 34, wherein: The utilization efficiency is at least 50 weight percent.

36. The method of claim 35, wherein: The utilization efficiency is at least 75 weight percent.

37. The method of claim 36, wherein: The utilization efficiency is 50 weight percent to 90 weight percent.

38. The method of claim 37, wherein: The utilization efficiency is 75 to 80 weight percent.

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