Method for synthesizing a platinum group metal-based catalyst on a carbon support

Abstract

A method for producing a platinum group metal-based catalyst on a carbon support includes the following steps: mixing a weighed quantity of a carbon support, ethylene glycol and a solvent, homogenizing the mixture and subsequently adding a palladium precursor, heating the reaction mixture to 80°С, holding the mixture at a constant temperature, adding a platinum precursor, heating the reaction mixture to 80°С, cooling the resulting suspension, adding a sedimentation agent in the form of 1 M NaCl, sedimenting the resulting mixture for 5 hours, filtering and drying. The technical result is the production of a catalyst that has improved activity indices and a reduced degradation rate.

Description

[0001]Method for Synthesizing a Platinum Group Metal (PGM)-Based Catalyst on a Carbon Support and Its Use in Catalytic Reactions Technical Field The invention relates to the production of a platinum group metal (PGM)-based catalyst on a carbon support, which is used on the cathode of a hydrogen-air fuel cell with a proton exchange membrane, and its use in catalytic reactions. Prior Art Field of Application: This invention relates to a method for producing a platinum group metal (PGM)-based catalyst on a carbon support, which is used for sputtering on the cathode of a fuel cell with a proton exchange membrane. Document CN 107482230 A discloses a method for producing a palladium carbon catalyst for a fuel cell.The method comprises the following steps: (1) respectively weighing a certain amount of palladium chloride and glycol, adding 50 ml of distilled water and dissolving to form a solution; (2) mechanically uniformly stirring the solution for 3-4 minutes; (3) stirring, and then taking a certain amount of carbon black and formaldehyde, adding to the solution, ultrasonic stirring and uniformly stirring; (4) heating the solution to 80 °C, stirring for 18-24 hours at a constant temperature, then raising the temperature to 100 °C and reacting for 10-20 minutes; (5) filtering impurities from the stirred solution and then washing; (6) drying after washing, thereby acquiring a palladium-carbon catalyst. The production method disclosed in the present invention has advantages such as low cost, excellent performance properties, etc.Document CN 101890347 B relates to a method for producing a catalyst supported on a proton-exchange membrane for a fuel cell. The method comprises dispersing soluble precursors of a carbon carrier and a metal active component in a mixed solvent of water and glycol in a reactor, stirring, and heating to 70-90°C. o C; adding formaldehyde solution and stirring at a temperature of 70 to 90 oC for 2-3 hours to obtain a solution containing a solid product; and filtration, elution, drying and calcination to obtain a catalyst supported on the proton exchange membrane of a fuel cell. When using the method of the invention, the reaction conditions are mild, the operation is simple, controllability is high, a high-temperature and non-aqueous system is not required, the addition of a surfactant is not required, and the pH of the system does not require adjustment. The obtained supported catalyst has high dispersibility. Document RU 2395339 describes catalysts for fuel cells, in particular a catalyst for a fuel cell cathode, as well as a method for producing the same. A catalyst for a fuel cell cathode is described, comprising an alloy of palladium and a metal selected from cobalt, chromium, vanadium, silver, copper, gold, platinum or a mixture thereof, on a carbon support, characterized in that it additionally contains amorphized carbon.Document RU 2455070 pertains to catalytic chemistry, specifically to the preparation of a catalyst with nanoscale platinum alloy particles on a carbon support for use in chemical power sources. The catalyst is produced using electrodes made of platinum alloys with transition metals in alkali metal hydroxide solutions with a concentration of 8 to 30% (by weight) under the action of alternating current at a frequency of 50 Hz and an average current per unit electrode surface area of ​​0.1-1.0 A / cm. 2The technical result enables the production of highly active catalysts with nanosized platinum alloy particles on a carbon support in a single step, without toxic reducing agents and elevated temperatures, which contributes to the improvement of the economic and environmental aspects of the technology. Document RU 2695999 relates to a method for producing catalysts with nanosized platinum particles and its alloys with metals for the cathode and anode of low-temperature fuel cells and electrolyzers, including the preparation of a solution of chloroplatinic acid or a mixture of chloroplatinic acid with metal salts in water or in an aqueous-organic solvent, mixing it with a powder of dispersed carbon or non-carbon supports, their mixtures and compositions with a specific surface area of ​​more than 60 m 2 / g, dispersing the resulting mixture. In this case, the chemical reduction of platinum compounds and a metal salt followed by the deposition of nanoparticles of metallic platinum or its alloys on a dispersed carrier is carried out by passing one of the gases, for example, nitrogen oxides (N2O, NO, NO2), or carbon oxides (CO, CO2), or sulfur oxide (SO2), or ammonia (NH3), or mixtures thereof, through the solution at a solution temperature of 5 to 98 °C. The technical result is the production of a catalyst with specified parameters with high values ​​of catalytic activity in the oxygen electroreduction reaction and specified values ​​of structural characteristics: small and medium-sized platinum / alloy nanoparticles in combination with a narrow size distribution, highly uniform distribution of nanoparticles over the carrier surface, and a high electrochemically active surface area of ​​platinum.The disadvantages of these methods include high energy consumption, the production of catalysts with low activity and low productivity of the proposed processes, and high raw material costs. The method for producing a catalyst according to patent CN 104174392 A comes closest to the essential features of the invention. The method, according to the prototype, involves a single-stage preparation process and contains specific steps: uniformly mixing the support with an aqueous solution of a reducing agent, a surfactant, a platinum metal precursor, and a non-platinum metal precursor, conducting the reaction for 0.5-5 hours, and repeated washing at a low temperature (less than or equal to 100°C) to effectively remove the surfactant and other byproducts. A disadvantage of this method is the production of a catalyst with low activity and a high degree of power degradation.Thus, there is a need to develop a new method for preparing an efficient catalyst with improved activity and reduced degradation. Brief description of the drawings Figure 1. X-ray diffraction patterns of iridium–palladium catalysts in mini-batches. Red circles indicate the peaks attributed to the metallic phase. Figure 2. TEM images of local areas of the studied prototype in different approximations. Histogram of the size distribution of nanoparticles. Figure 3. Examples of typical cyclic voltammograms of intermediate mini-batches. 0.1 M HClO4 solution saturated with Ar. Figure 4. Linear voltammograms of the oxygen reduction reaction. Rotation speed 1600 rpm. Potential scan rate 20 mV / s, 0.1 M HClO4 solution saturated with O2. Figure 5. Histograms of ESA change during stress testing: initial value (black); after 1000, 5000 and 10,000 cycles (shaded); residual value after 20,000 cycles (gray). Figure 6.Cyclic voltammograms of the electrocatalyst before and after 10,000 stress testing cycles. Potential range 0.6 – 1.0 V (ORH), 10,000 cycles; 0.1 M HClO4 solution saturated with Ar. Figure 7. Linear voltammograms of the oxygen reduction reaction before and after stress testing. Rotation speed 1600 rpm. Potential scan rate 20 mV / s, 0.1 M HClO4 solution saturated with O2. Figure 8. Polarization and loading curves of the OEA with test prototype #4-FC on the cathode. Three measurement reproductions (deposition, assembly, measurement). Figure 9. Polarization and load curves of the initial MEA after 1000, 5000 and 10000 cycles during the stability measurement of the prototype for testing #4-FC and the commercial analogue HiSPEC4000. Figure 10. Power curves of the initial MEA of the prototype for testing #4-FC after 1000, 5000, 10000 and 30000 cycles during the stability measurement. Figure 11.Histograms of power changes during long-term testing in the OIE: initial value (black); after 1000, 5000 and 10000 cycles (shaded); residual value after 30000 cycles (gray). Figure 12. TEM images of local areas of the studied prototype and a commercial comparison sample. Histograms of the size distribution of nanoparticles in the samples. The essence of the invention The technical result consists in obtaining a catalyst based on a platinum group metal (PGM) on a carbon support, which has improved characteristics, such as activity in the catalytic reaction, electrochemically active surface area, as well as a reduced degree of degradation and reduced degradation in power and activity compared to a commercial analogue. Methods and materials 1.1 Reagents, concentration • Palladium (II) chloride, PdCl2 (mass fraction of Pd 60.02%, Aurat, TU 2625-048-00205067-2003) • Hexachloroiridic acid, H2PtCl6*6H2O (mass fraction of Pt 37.78%, Aurat, TU 2612-034-00205067-2003) • Vulcan XC-72 (Cabot Corporation) • Ethylene glycol, C2H4(OH)2, (analytical grade, 99.5%, GOST 10164-75, JSC EKOS-1, Russia) • Isopropanol, C3H7OH (special purity grade, 99.8%, TU 2632-181-44493179-2014, JSC EKOS-1) • Formaldehyde, HCOH (FM, premium grade, 37.5%, GOST 1625-2016, JSC VEKTON) • Sodium chloride, NaCl (analytical grade, 99.9%, GOST 4166-76, OOO «МЗХР») • Sodium hydroxide, NaOH (analytical grade, 98%, GOST 4328–77, Komponent-Reaktiv LLC) • Double-distilled water (electrical conductivity <5 μS / cm, GOST 58144–2018) • Universal indicator paper (EKROSKHIM, TU 2642-054-23050963-2008) 1.2 Chemical glassware • Reactor (tall chemical beaker, 600 ml, made of heat-resistant glass) – 1 pc. • Tall chemical glass beaker, 50 ml – 2 pcs. • Glass rod, 220 mm – 1 pc. • Heat-resistant glass container, 2 l – 1 pc. • Dispenser tip (mechanical pipette), single-channel, 5 ml – 4 pcs. • Double-sided chemical spoon, stainless steel – 2 pcs. • Glass chemical spoon – 2 pcs.• Glass graduated cylinder, 100 ml – 4 pcs. • Graduated flask, 100 ml – 3 pcs. • Graduated flask, 200 ml – 1 pc. • Watch glass, d-100 mm – 2 pcs. • Glass laboratory funnel, d-30 mm – 2 pcs. • Petri dish – 1 pc. • Penicillin bottle, 10 ml – 1 pc. • Ash-free filter, blue tape, d-9 cm (TU 2642-001-42624157-98) – 2 pcs. • Buchner funnel, d-10 cm – 1 pc. • Bunsen flask, 500 ml – 1 pc. • Double-sided chemical spatula, stainless steel, 20 cm – 1 pc. • Glass chemical beaker, 1000 ml – 1 pc. 1.3 Instrumentation • Laboratory scales VLTE-410S – 1 pc. • Glass double-distiller BS (TU 25–11.1592–81, 5.5 kVA) – 1 pc. • Mercury thermometer (GOST 13646–68) – 1 pc. • Magnetic stirrer IKA C-MAG HS 7 – 1 pc. • Flat Teflon magnetic anchor, 40x8 mm – 1 pc. • Vacuum drying oven with heating 250 °C (VAC-52) – 1 pc. • Ultrasonic homogenizer (SX-SONIC 1200N1935) – 1 pc. • Dispenser (mechanical pipette) for 5 ml – 1 pc. • Magnetic anchor extractor – 1 pc.• Laboratory vacuum pump 2VP-2, 120 l / min (Stegler) – 1 pc. • Laboratory vacuum pump VP-10L, 10 l / min (JOANLAB) – 1 pc. 1.4 Preparation of reagents The required amounts of metal precursors and reagents were calculated based on the catalyst composition and the metal ratio. Preparation of metal precursor solutions • PdCl2 solution 0.05 mol / l. A sample of PdCl2 weighing 0.8873 g, weighed on an electronic scale, was dissolved in 100 ml of an aqueous solution of 0.1 M hydrochloric acid (36.23% HCl). A sample of the salt was weighed on a watch glass, then the sample was transferred to a 100 ml measuring flask, washing off the residue from the watch glass with an aqueous solution of 0.1 M hydrochloric acid. Then the volume of hydrochloric acid was brought to the mark and mixed. To obtain a catalyst of the given composition, 11.57 ml of a palladium precursor solution were used. • H2PtCl6*6H2O solution 0.05 mol / l. A sample of H2PtCl6*6H2O weighing 5.1615 g, weighed on an electronic scale, was dissolved in 200 ml of bidistilled water.A weighed portion of the salt was weighed on a watch glass, then transferred to a 200 ml measuring flask, washing away the residue from the watch glass with bidistilled water. Then, the volume was brought to the mark with bidistilled water and mixed. To obtain a catalyst of the given composition, 34.70 ml of a platinum precursor solution were used. Preparation of reagent solutions • 1 mol / L NaOH solution. A weighed portion of NaOH weighing 3.9997 g, weighed on an electronic scale, was dissolved in 100 ml of bidistilled water. A weighed portion of the alkali was weighed in a 50 ml chemical glass beaker, then transferred to a 100 ml measuring flask, washing away the residue from the beaker with bidistilled water. Then, the volume was brought to the mark with bidistilled water and mixed. To obtain a catalyst of the given composition, 23.15 ml of a sodium hydroxide solution were used. • NaCl solution 1 mol / l. A sample of NaCl weighing 5.8440 g, weighed on an electronic scale, was dissolved in 100 ml of bidistilled water.A sample of salt was weighed in a 50 ml chemical glass beaker, then the sample was transferred to a 100 ml measuring flask, washing away the residue from the beaker with bidistilled water. Then the volume was brought to the mark with bidistilled water and mixed. For sedimentation of the catalyst of the given composition, 100.00 ml of sodium chloride solution were used. Preparation of reagent solutions • Ethylene glycol C2H4(OH)2 (99.5%) was measured out with a graduated cylinder 215 ml. • Formaldehyde HCOH (37.5%) was measured out with a dispenser 11 ml. Examples of the invention Example No. 1. Catalyst Synthesis 1.1 To obtain 1 g of electrocatalyst, 215 ml of ethylene glycol (used as a solvent and stabilizing agent (solvent medium)) measured with a graduated cylinder were poured into a 600 ml chemical tall beaker (reactor). Next, a weighed portion of Vulcan XC-72 carbon support (0.6 g) and a magnetic anchor were placed in the reactor, and the mixture was stirred for 10 minutes at 400 rpm. Reagents were used at room temperature (23 ℃). 1.2 Next, the reaction mixture was homogenized in an ultrasonic homogenizer 3 times for 1 minute with an amplitude of 50%. Before each homogenization, the reaction mixture was stirred at room temperature for 10 minutes. After three homogenizations, the mixture was stirred for 20 minutes at 400 rpm. 1.3 Then, 11.57 ml of palladium precursor, 23.15 ml of 1 M sodium hydroxide solution and 11 ml of formalin were added to the reaction mixture using a dispenser with a 5 ml dispenser and stirred for 10 minutes at 400 rpm. Next, using universal indicator paper, the pH of the reaction medium was determined (the pH should be within 11). A sample was performed by immersing a glass rod into the reaction medium in order to transfer a microquantity of the solution to the indicator paper. 1.4 The reactor was immersed in a laboratory bath with a coolant. The laboratory bath is a 2-liter heat-resistant glass container filled with ethylene glycol as a coolant.The laboratory bath was placed on a magnetic stirrer with heating and stirred at 400 rpm, while simultaneously turning on heating on a magnetic stirrer to 80 ℃ in the reaction mixture. After reaching a temperature of 80 ℃, the reaction mixture was kept at a constant temperature (80 ℃) and continuous stirring at 400 rpm for 4 hours. 1.5 Then, 34.70 ml of platinum precursor was added using a dispenser. After reaching a temperature of 80 ℃, the reaction mixture was kept at a constant temperature (80 ℃) and continuous stirring at 400 rpm for 4 hours. 1.6 Upon completion of the synthesis, the suspension was cooled at room temperature for 12 hours, after which a solution of sedimentation agent (1 M NaCl) in an amount of 100 ml was added using a measuring cylinder and the reaction mixture was stirred for 5 hours. Then the magnetic anchor was removed from the reaction medium and the mixture was left without stirring for 5 hours for sedimentation. 1.The filtration of the resulting suspension was carried out at room temperature (23°C). The filtration system was assembled by connecting a Bunsen flask to a pump. Next, a Buchner funnel was inserted into the neck of the flask, and two Blue Ribbon filters were placed inside. The filters were moistened with 10 ml of bidistilled water, and the pump was turned on so that they fit tightly to the surface of the funnel. First, the upper layer of the mother liquor was poured into the Buchner funnel by turning on the pump and creating pressure. If the solution that passed through the filter turned black, it was filtered again. Next, the precipitate was similarly filtered until the solution in the flask was clear. The precipitate on the filter was washed with five 30 ml portions of bidistilled water, measured using a graduated cylinder. The precipitate was then washed with a mixture of water and isopropanol. To prepare the mixture, 90 ml of isopropanol, measured out using graduated cylinders, were mixed with 210 ml of bidistilled water in a 1000 ml glass beaker.Next, the sediment was washed to remove residual isopropanol with five 30 ml portions of bidistilled water. The resulting filter cake was transferred to a Petri dish using a chemical spatula. The filter and sediment in the Petri dish were dried in a vacuum drying oven at 70°C for 5 hours. The Petri dish with the filter cake was then transferred to a desiccator and dried over P2O5 for 12 hours. The dried sample was scraped from the filter, transferred to a penicillin vial, and the mass of the resulting material was recorded on an analytical balance. Table 1. Target characteristics of prototype #4-FC for testing, weighing 10.0 grams. Example 2. Prototype Composition Study 2.1 Gravimetric Analysis The gravimetric method involves determining the mass fraction of metals contained in prototype for test #4-FC based on the change in mass before and after measurement. Ceramic crucibles were pre-calcined in a muffle furnace (UED-7-10D, Russia) at 800°C. After complete cooling, they were weighed, recording their mass (mcrucible), and filled with a catalyst sample (mweight ≈ 0.02g). The crucibles were then re-immersed in the furnace at the same temperature and left for 40 min. After this time, the crucibles with the metal component were cooled to room temperature, and the mass of the residue (mresist) was recorded. The mass fraction was calculated using the formula: ^=(mcrucible+rest-mcrucible) / mweight ×100%. The determined mass fraction of all mini-batches is shown in Table 2. 2.2 Study of the prototype structural characteristics using powder diffractometry (XRD). X-ray diffraction patterns were recorded on an ARL X`TRA powder diffractometer (ThermoScientific, USA) (Faculty of Chemistry, Southern Federal University). An ARL X`TRA diffractometer with Bragg-Brentano (θ-θ) geometry and CuKα radiation (λ = 0.154056 nm) was used at room temperature. X-ray diffraction patterns of the studied samples were recorded in the angular range of 150 ≤ 2θ ≥ 750 using the step-by-step scanning method with a detector movement step of 0.02̊. X-ray diffraction patterns were processed using the SciDavis software. The X-ray diffraction patterns of the mini-batches show peaks in the 2-theta angle ranges of 40-41, 46-47, and 68-69 degrees, confirming the presence of a metallic phase (Fig. 1). The location of the peaks in the X-ray diffraction patterns of the samples confirms the formation of a platinum-palladium alloy, as the peaks are shifted relative to the standard arrangement of platinum and palladium.The average crystallite size calculated using the Scherrer equation for the most intense peak is 2.0-2.4 nm for all mini-batches (Table 2). The obtained values ​​do not exceed 10% error from the established target value (Table 1) 2.3 Determination of Chemical Composition by TXRF The metal ratio in the samples was determined by X-ray fluorescence analysis (TXRF) using an RFS-001 total external reflection X-ray spectrometer (Research Institute of Physics, Southern Federal University, Rostov-on-Don). The sample exposure time was 300 s. Registration and processing of X-ray fluorescence spectra were performed using the UniveRS software (Southern Federal University, Rostov-on-Don). Then, the metal ratio (Pt:Pd) was determined by TXRF (Table 2). Based on the analysis results, it was established that the composition of the materials is within the permissible error limits (10%).The table also shows deviations from the specified content in atomic units of platinum and palladium (Tables 1, 2). The ratio of metals in the samples was determined by X-ray fluorescence analysis (TXRF) on an RFS-001 total external reflection X-ray spectrometer (Physics Research Institute, Southern Federal University, Rostov-on-Don). The sample exposure time was 300 s. Registration and processing of X-ray fluorescence spectra were performed using the UniveRS program (Southern Federal University, Rostov-on-Don). Table 2. Results of determining the content of components (Pt and Pd) in the sample by TXRF. The mass content of metals was converted to the atomic ratio: The Pt / Pd atomic ratio of the metallic component determined by TXRF is 2.96, which corresponds to the Pt composition 75 Pd 25. The obtained value corresponds to the declared target value of this parameter. 2.4 Determination of chemical composition by the ICP AC method Samples were mineralized on an electric hotplate at a temperature of 200 degrees for 2 hours with a mixture of concentrated hydrochloric and nitric acids (aqua regia) in a Milestone Ethos-1 microwave mineralization unit. The measurement was carried out using a ThermoiCap 7400Duo ICP-AC spectrometer. The ICP-AC spectrometer was calibrated using a multi-element standard including the components to be determined. According to the results of determining the mass content of the components in the studied sample, Pt is 36±11%, and Pd is 6.8±2.0%. When recalculating the mass content of the components to the atomic content, the Pt / Pd ratio is 2.89, which corresponds to the composition of the metal component Pt74Pd26. The obtained value does not exceed the established requirement for an error of no more than 10% of the specified target value (Table 1). 2.5 Study of the Microstructure of the Material Based on the Results of Transmission Electron Microscopy (TEM) The microstructural features of the sample were studied by transmission electron microscopy (TEM) using a JEOL JEM F200 microscope (JEOL, Japan) with an attachment for elemental mapping of the sample surface area (High-Resolution Microscopy Collective Use Center of the Southern Federal University). Sample preparation was performed by preparing a catalyst suspension in isopropanol and applying a 3 μl aliquot to a copper grid for measurement. Histograms of the size distribution of nanoparticles in the catalysts were constructed based on the results of determining the sizes of at least 100 particles randomly selected from TEM images in different areas of the sample using DigimizerImageAnalysisSoftware. The calculated average size of nanoparticles in the studied sample, according to TEM data, is 2.6 nm (Fig. 2). The obtained value corresponds to the established target value (Table1) Fig. 2 shows TEM images of local areas of the surface of a Pt prototype sample. 75 Pd 25 / C. The presence of a metallic phase is observed (dark areas in all TEM photographs). A large proportion of nanoparticles are uniformly distributed over the surface of the carbon support. Example 3. Electrochemical research methods (voltammetry) Electrochemical measurements were carried out in a three-electrode cell on a VersaSTAT potentiostat (AMETEK Scientific Instruments, USA) using a rotating disk electrode (Pine Research Instruments, USA). Saturated silver chloride was used as a reference electrode. A platinum wire was used as an auxiliary electrode. Activation of the catalyst surface was carried out in a three-electrode electrochemical cell, which was filled with 100 ml of 0.1 M HClO4 electrolyte. The electrolyte was bubbling with an inert gas (Ar) for 30 minutes. Cyclic voltammograms (CVA) were recorded in the potential range of 0.025–1.0 V with a potential scan rate of 500 mV / s for 100 cycles. Example 4.Determination of the active surface area (voltammetry for area determination) After activation, the cyclic voltammogram was recorded in the potential range of 0.025–1.0 V with a potential scan rate of 20 mV / s for 3 cycles. The electrochemically active surface area (ESA) of the sample was calculated from the hydrogen adsorption / desorption peaks from the obtained voltammograms (Figs. 3, 4). It was calculated from the amount of electricity spent on hydrogen desorption Q' and adsorption Q" using the formula: where mМПГ is the metal loading on the electrode; 0.2065 μC / cm 2 – the amount of electricity spent on the adsorption of hydrogen per 1 cm 2 surface of MPG (μC / cm 2). The calculated ESA values ​​(Table 2) of the mini-batches do not exceed 10% error from the established target value (Tables 1, 2). Example 5. Study of activity in the catalysis reaction (oxygen reduction reaction) (voltammetry for determining activity) After determining the ESA, a linear potential sweep voltammogram (LSV) was recorded in the potential range of 0.05–1.1 V (1 cycle) at an electrode rotation speed of 1600 rpm - background curve. Then, the electrolyte was replaced with fresh one and saturated with oxygen for 60 minutes. Voltammograms were recorded in the potential range of 0.05–1.1 V at electrode rotation speeds of 400, 900, 1600, 2500 rpm for 1 cycle at each speed. The potential was recalculated taking into account the resistance (iRcompensation) and the potential value in a deoxygenated solution (Ar atmosphere).Using the Koutecky–Levich relationship, we found the value of the kinetic parameters of the oxygen reduction reaction (mass activity) for an E1 / 2 value of 0.90 V. The calculated values ​​of catalytic activity (Table 2) of the mini-batches do not exceed 10% of the error from the established target value (Table 1). Conclusions For the 13 mini-batches obtained: – The yield of the target product was at least 80%. – The mass fraction of metals, determined by gravimetry, was at least 37.5%. – The presence of a metallic phase was confirmed by XRD. – The average crystallite size does not exceed 2.4 nm. – The composition of the metal component, determined by TXRF, ranged from Pt73Pd27 to Pt77Pd23. – The active surface area was 82−104 m. 2 / g(Pt). – Activity in the oxygen reduction reaction of at least 378 A / g(Pt). The total mass of 13 mini-batches (samples) for combining and studying was 11.77 (eleven point 77) grams. Example 6. Start-Stop Protocol (Toyota Protocol) (Toyota Protocol https: / / iopscience.iop.org / article / 10.1149 / 2.0161907jes) Step 1. The electrolyte (0.1 M HClO4) in the cell was saturated with argon for 30 minutes. Standardization of the working electrode surface was carried out by cyclic voltammetry, setting 100 potential sweep cycles in the range from 0.025 to 1.00 V, with a potential sweep rate of 500 mV / s. Step 2. The initial ESA was measured at the stationary electrode by recording three cyclic voltammograms in the potential range of 0.025–1.00 V with a potential scan rate of 20 mV / s. The ESA was calculated as the half-sum of the amount of electricity spent on the adsorption and desorption of the hydrogen monolayer in the second CV. Step 3.To evaluate the initial activity of the catalysts in the catalytic reaction (oxygen reduction reaction), the background potentiodynamic polarization curve was measured in an argon atmosphere at a disk electrode rotation speed of 1600 rpm in the potential range from 0.05 to 1.1 V with a potential scan rate of 20 mV / s. The electrolyte was then replaced with a freshly prepared one and saturated with oxygen for 1 hour. Subsequently, potentiodynamic curves were measured with a potential scan rate of 20 mV / s in the potential range from 0.05 to 1.1 V at four disk electrode rotation speeds: 400, 900, 1600, and 2500 rpm. Step 4. Stress testing was performed in an oxygen-saturated electrolyte on a stationary electrode at potentials of 0.4 and 1.0 V, holding at each potential for 3 seconds, and repeating the measurement for 10,000 cycles (17 hours). Step 5.Upon completion of the stress test, the electrolyte was replaced with fresh one, saturated with argon for 30 minutes, and ESA after the stress test was measured by repeating step 2 (Fig. 6). Step 6. To measure the final value of activity in the OCR reaction, step 3 was repeated (Fig. 7). The degradation rate (DR) value was calculated from the change in ESA and mass activity in OCR. The degree of degradation of ESA and mass activity in OCR (Fig. 5) was calculated using the following formulas: Degradation by ESA = ((ESAINitial – ESAafter ST) / ESAINitial)*100% Degradation by mass activity = ((IINitial – Iafter ST) / IINitial)*100%. The results of residual characteristics after stress testing and the degree of degradation are presented in Table 3. Table 3. Values ​​of residual ESA and mass activity after stress testing in two protocols and the degree of degradation. Example 7. Method of catalysis The catalyst obtained in Example 1 was converted into the form of catalytic ink using the procedure described below. A catalyst suspension (catalytic ink) was obtained by adding 3600 μl of isopropyl alcohol, 300 μl of deionized water, and 100 μl of a 1% aqueous emulsion of Nafion® polymer to a sample of 0.0060 g of the prototype. The suspension was then dispersed ultrasonically for 25 minutes while maintaining a temperature of no higher than 20 0 Before applying the suspension, the glassy carbon end of the rotating disk electrode was polished and then rinsed in isopropyl alcohol. The prepared catalytic ink was used to deposit a thin catalyst layer on the glassy graphite electrode. A 2.5 μL aliquot of the "ink" was collected using a microdispenser with continuous stirring and applied to the end of a polished and degreased glassy carbon electrode with an area of ​​0.196 cm. 2, after which the electrode was dried for 15 minutes in isopropyl alcohol vapor. After the first drop of catalytic ink had dried, a second drop of the same volume was applied. In this case, the total drop volume should be 5±1 μl, and the metal loading at the end of the RDE should be 20.0±1 μg / cm 2 . Thus, the electrode under study is a uniform catalyst layer fixed to the end of a rotating disk electrode. The resulting catalyst was then placed in a cell and the catalytic reactions (oxygen reduction reactions) were carried out, as described further in Example 8. Example 8. Testing in a single membrane-electrode assembly 8.1 Ink preparation method To prepare cathode ink and form an MEA with an active area of ​​5 cm 2To a catalyst sample containing 1.8 mg of MPG, add 450 µl of deionized water, 225 µl of high-purity isopropyl alcohol, and 20 µl of a 10% aqueous Nafion® solution. Losses during the formation of the catalytic layer by spraying must be taken into account; the values ​​given assume a 20% excess by weight and volume. Next, ultrasonic homogenization must be performed for 1-1.5 hours in an ultrasonic bath with an operating frequency of 35 kHz; the water temperature must not exceed 25°C. Mechanical shaking is additionally performed for 1-2 minutes every 15-20 minutes. The Nafion:carbon ratio for cathode ink should be 7:10 (0.7), according to the calculation below: Amount of carbon in the sample: – 0.0047 g sample weight (mcat) – platinum group metal content 38.2%, then C – 61.8% mc = mcat * 0.618 = 0.0047 * 0.618 = 0.0029 g – mass of carbon Mass of Nafion with Nafion / C ratio – 0.7: mNafion = mc * 0.7 = 0.0029 * 0.7 = 0.0020 g.Mass of 10% Nafion D1021 dispersion: mpolymer dispersion = 0.0020 g * 100% / 10% = 0.020 g Volume of 10% Nafion dispersion to be added: Vpolymer dispersion = m / p = 0.020 g / 1 g / ml = 0.020 ml = 20 μl p is the density of 1 g / ml. To prepare the anodic ink and form an MEA with an active area of ​​5 cm. 2To a catalyst sample containing 2.4 mg of MPG, add 600 µl of deionized water, 300 µl of high-purity isopropyl alcohol, and 25 µl of a 10% aqueous Nafion® solution. Losses during the formation of the catalytic layer by spraying must be taken into account; the values ​​given assume a 20% excess by weight and volume. Next, ultrasonic homogenization must be performed for 1-1.5 hours in an ultrasonic bath with an operating frequency of 35 kHz; the water temperature must not exceed 25°C. Mechanical shaking is additionally performed for 1-2 minutes every 15-20 minutes. The Nafion:carbon ratio for the anode ink should be 7:10 (0.7), according to the calculation below: Amount of carbon in the sample: – 0.006 g sample weight (mcat) – platinum group metal content 40%, then C – 60% mc = mcat * 0.6 = 0.006 * 0.6 = 0.0036 g – mass of carbon Mass of Nafion with a Nafion / C ratio of – 0.7: mNafion = mc * 0.7 = 0.0036 * 0.7 = 0.0025 g.Mass of 10% Nafion D1021 dispersion: mpolymer dispersion = 0.0025 g * 100% / 10% = 0.025 g Volume of 10% Nafion dispersion to be added: Vpolymer dispersion = m / p = 0.025 g / 1 g / mL = 0.019 mL = 25 µL p is the density of 1 g / mL. 8.2 Preparing the membrane for sputtering Protective films should be removed from both sides of the membrane cut to the required MEA size, then the membrane is weighed. Next, the membrane sample is soaked in deionized water saturated with argon at atmospheric pressure and stored in a dark place in a closed container for at least 24 hours (or more). After 24 hours or more of exposure, the wet membrane is placed in a special fixture, clamped, and kept in a desiccator over a saturated MgCl2 solution with sediment for at least 12 hours (or more) to remove excess moisture and water from the membrane surface. 8.3 Spraying catalytic ink onto the membrane 1.After the proton exchange membrane is dry and clamped, it is placed in a heating oven for ink application. 2. The catalyst ink is sprayed alternately onto both sides of the membrane. Detailed spraying parameters: JAS 1186 airbrush, nozzle diameter 0.2 mm. Platform heating - 90 ⁰С. 3. Weighing the membrane with the deposited catalyst layers to control the mass. 8.4 Single MEA Assembly The MEA is assembled by hot pressing. For this, the membrane with the deposited catalyst layers (anode and cathode) is placed between GDL sheets. The resulting MEA is then placed between two insulating gaskets, which are pre-wiped thoroughly with acetone, dried, and transferred to a press, where the assembly is pressed for 3 minutes at a temperature of 130 ⁰С and a pressure of 80 kg / cm. 2. After pressing, cool the assembly at room temperature for 10-15 minutes. 8.5 Storage of catalytic ink After preparation, store catalytic ink in a glass container with a tightly closed lid at a temperature of 10-25 ⁰C. Do not allow the ink to heat up. Do not store ink with the lid open for more than 15 seconds. The shelf life of catalytic ink is no more than 24 (twenty-four) hours. If the ink heats up or the lid is left open for more than 15 seconds, prepare a new batch of catalytic ink. 8.6 Study of the activity of catalytic materials in a membrane-electrode unit Study of the performance of the cathode catalyst in a single PaxiTech cell with an active area of ​​5 cm 2Conducted on the BioLogic FCT-50S station. Gas pressure 1.5 bar; humidifier temperature 59 ⁰C; gas channel temperature 80 ⁰C; cell temperature 75 ⁰C. Hydrogen with a purity of 99.999% serves as the anode gas, and filtered air (primary filtration from dust) with an oxygen content of 21% serves as the cathode gas. The anode gas flow is 220 ml / min, the cathode gas flow is 680 ml / min. Next, it is necessary to set the load to 3 A and maintain the cell until the cell potential does not fluctuate more than +- 5 mV for 15 minutes, but for a total of no more than 4 hours. Then set a step load from 1 A to 10 A in 1 A increments, with the lower current limit selected so that the cell potential does not fall below 0.2 V. Next, it is necessary to carry out the step load in the opposite direction to 0.1 A, and after 1 A, the step should be changed and the points set are 1 A - 0.5 A - 0.25 A - 0.1 A and back 0.1 A - 0.25 A - 0.5 A - 1 A (Fig. 8). Example 9.Characteristics of the MEA Next, the characteristics of the obtained sample were studied (Table 4) Table 4. Characteristics of the MEA with the prototype for testing No. 4-FC and a comparison sample with the commercial analogue HiSPEC4000. Example 10. Study of the stability of catalytic materials in a membrane-electrode unit over 10,000 cycles Study of the stability of the cathode catalyst in a catalysis reaction carried out in a single PaxiTech cell with an active area of ​​5 cm 2, carried out on the BioLogicFCT-50S station. The gas pressure is atmospheric, the temperature of the humidifiers, gas lines and cell is 80 ⁰C. Hydrogen with a purity of 99.999% serves as the anode gas, argon with a purity of 99.99% serves as the cathode gas. The anode gas flow is 200 ml / min, the cathode gas is 75 ml / min. Then it is necessary to carry out a square wave cycle of 0.6 V for 3 seconds and 0.95 V for 3 seconds (1 cycle) for 10,000 cycles. In this case, after 1000, 5000 and 10,000 cycles it is necessary to measure the performance of the cathode catalyst according to Fig. 9. According to the results of long-term testing at the OIE, the prototype for testing degrades by no more than 22% after 10,000 cycles (Table 5). Table 5. Comparative characteristics table of the prototype for testing No. 4-FC and the HiSPEC4000 analogue. Specific power characteristics (mW / cm 2 ) and mass (W / g(MPG)) Example 11. Study of the service life of catalytic materials in a membrane-electrode unit over 30,000 cycles Study of service life tests of a cathode catalyst in a single PaxiTech cell with an active area of ​​5 cm 2 carried out on the BioLogicFCT-50S station. The gas pressure is atmospheric, the temperature of the humidifiers, gas lines and cell is 80 ⁰С. Hydrogen with a purity of 99.999% serves as the anode gas, argon with a purity of 99.99% serves as the cathode gas. The anode gas flow is 200 ml / min, the cathode gas flow is 75 ml / min. Then it is necessary to carry out a square wave cycle of 0.6 V for 3 seconds and 0.95 V for 3 seconds (1 cycle) for 30,000 cycles. In this case, after 1000, 5000, 10,000 and 30,000 cycles it is necessary to measure the performance of the cathode catalyst (Figs. 10, 11) (Table 6). Table 6. Results of the power characteristics of the prototype for testing No. 4-FC during testing of 30,000 cycles Based on the results of a comprehensive study of the composition, structural, morphological, and electrochemical characteristics, the target characteristics of prototype for testing No. 4-FC were confirmed (Tables 7, 8). Table 7. Characteristics of prototype for testing No. 4-FCPt75Pd25 / C, determined during testing. Deviations from target values ​​(composition and activity) are indicated. Table 8. Comparative characteristics of the prototype for testing No. 4-FCPt 75 Pd 25 / C determined during testing, compared to the commercial equivalent HiSPEC4000 (JohnsonMatthey, 40% Pt) – Localized areas of test prototype #4-FC contain isolated agglomerates of nanoparticles measuring 5-7 nm. – The commercial comparison sample HiSPEC4000 is characterized by an uneven distribution of nanoparticles over the carbon support surface. There are localized areas with agglomerates measuring 20-25 nm. – The commercial comparison sample HiSPEC4000 is characterized by a broad nanoparticle size distribution of 4-6 nm. The average nanoparticle size is approximately 5 nm. The above-mentioned microstructural features of electrocatalysts affect the quality of the material, its electrochemical characteristics, and its efficiency in the MEA. The uniform distribution of nanoparticles over the carbon support surface, narrow size distribution, and average size of approximately 3 nm ensure high ESA values ​​and mass activity in the oxygen reduction reaction. These parameters also ensure the material's resistance to degradation due to slow migration and agglomeration of nanoparticles.All of the listed features allow us to conclude that the developed product has high quality and is promising for its use in the OIE.

Claims

Claim 1. A method for producing a catalyst based on a platinum group metal on a carbon carrier for use on the cathode of a hydrogen-air fuel cell with a proton exchange membrane, comprising the following stages: - mixing a weighed portion of the carbon carrier, ethylene glycol and a solvent; - homogenization followed by the addition of a palladium precursor; - heating the resulting reaction mixture to 80 ℃; - maintaining at a constant temperature with continuous stirring for 4 hours; - adding a platinum precursor; - heating the resulting reaction mixture to 80 ℃; - maintaining at a constant temperature with continuous stirring for 4 hours; - cooling the resulting suspension at room temperature for 12 hours; - adding a sedimentation agent 1 M NaCl with continuous stirring for 5 hours; - sedimentation of the resulting mixture without stirring for 5 hours;– filtration and drying to obtain a catalyst based on a platinum group metal on a carbon support.

2. The method according to claim 1, wherein the filtration does not necessarily include washing the precipitate with a water / isopropanol mixture.

3. The method according to claim 1, wherein the drying is carried out in a vacuum drying oven at 70 ℃ for 5 hours.

4. A method for catalyzing the oxygen reduction reaction, comprising the following steps:; – obtaining a catalyst by the method according to paragraphs 1-3 of the formula; – spraying the obtained catalyst onto the cathode of a hydrogen-air fuel cell with a proton exchange membrane; – carrying out a catalytic reaction.

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