Electrocatalyst for proton exchange membrane fuel cell and its process of preparation thereof

Abstract

The present invention relates to membrane fuel cells. Specifically, the present invention relates to an electrocatalyst comprising dual metal alloy enriched with 2D twin and grain boundary defects, controlled particle size and modulated d band center by hot injection modified polyol method. The invention also relates to a proton exchange membrane fuel cell comprising said electrocatalyst.

Description

[0001] PT / 2025 / 13854

[0002] ELECTROCATALYST FOR PROTON EXCHANGE MEMEBRANE FUEL CELL

[0003] AND ITS PROCESS OF PREPRATION THEREOF

[0004] FIELD OF THE INVENTION

[0005] The present invention relates to membrane fuel cells. Specifically, the present invention relates to an electrocatalyst comprising a dual metal alloy enriched with 2D twin and grain boundary defects by hot injection modified polyol method. The invention also relates to a proton exchange membrane fuel cell comprising said electrocatalyst.

[0006] BACKGROUND OF INVENTION

[0007] Many researchers, academics and companies as well are very interested in the study of the electrochemical catalytic conversion of carbon oxides and renewable power into chemical fuels. Through a closed technical carbon cycle in which chemical fuels, such hydrogen, are stored and then turned back into power through electrochemical reaction processes in fuel cells. This technique primarily aims to mitigate the global energy issue by the creation of stable and high-catalytic-activity nanomaterials combined with high-performance polymeric membranes to lessen the amount of platinum group metal used as a cathode in the construction of stacks of proton exchange membrane fuel cells (PEMFCs) that operate at low and moderate temperatures.

[0008] Proton-exchange membrane fuel cells show great promise for a variety of energy conversion technologies. The proton-exchange membrane (PEM) fuel cell is a device that includes three essential components; a cathode, an anode, and an electrolyte membrane. This fuel cell technology is a vital source of clean energy and is widely used in various industries for its efficiency and reliability. At the anode, hydrogen is oxidized while oxygen is reduced at the cathode. Electrons are carried over an external circuit load, while protons are transported through the electrolyte membrane from the anode to the cathode. On the cathode, oxygen reacts with protons and electrons, resulting in the generation of heat and the formation of water as a by-product.

[0009] The commercialization and development of Proton Exchange Membrane Fuel Cells (PEMFCs) is hindered by two significant factors: stability and durability. Also, while platinum is effective, stable, and has high exchange current density and work function, it's expensive and easily poisoned. Moreover, these systems suffer certain distress related to their activity, durability, PT / 2025 / 13854 and stability in the long run. The reason for these setbacks has been probed through theoretical studies, revealing stronger interactions between intermediates and platinum, which impede the reaction kinetics. Concerns regarding durability and stability arise from the formation of Pt-Oxspecies during the reaction process, leading to leaching and agglomeration of platinum particles, thereby diminishing active sites. Researchers seek an electrocatalyst to improve current and stability at a practical scale PEMFCs are expensive due to the use of platinum as catalysts, which account for 55% of manufacturing costs. These together snag the outcome of PEMFC in terms of final performance.

[0010] The field of proton exchange membrane fuel cells (PEMFCs) has long been recognized for its potential to provide clean and efficient energy solutions. However, the widespread adoption of PEMFCs has been hindered by several significant challenges, including high material costs, limited durability, and suboptimal catalytic activity. A considerable portion of these issues arises from the reliance on platinum (Pt)-based catalysts, which, while effective, are expensive and prone to degradation over time. Specifically, the strong interaction between platinum and oxygen intermediates during the oxygen reduction reaction (ORR) leads to sluggish reaction kinetics, the formation of Pt-Ox species, and eventual leaching or agglomeration of platinum particles. These phenomena reduce the number of active sites, thereby affecting the long-term stability and performance of the catalyst. Additionally, the high cost of platinum, which accounts for a substantial portion of PEMFC manufacturing expenses, has been a persistent barrier to commercialization.

[0011] In CN106040234 B a method for preparing platinum-gallium alloy nano catalysts using a hot injection technique, resulting in nanoparticles of 4-6 nm for membrane fuel cell applications is disclosed. However, the document does not disclose suitable particle sizes of shape transformations of the electrocatalyst or even any specific technical effect as apparent from a device comprising the electrocatalyst.

[0012] In another article “ Enhancement of oxygen reduction reaction activity by grain boundaries in platinum nanostructures" by Zhu et.al., Tsinghua University Press and Springer- Verlag GmbH Germany, Springer Nature 2020, it is disclosed that platinum nanostructures with high grain boundary densities exhibit significantly enhanced oxygen reduction reaction (ORR) activity, with ultrathin nanoplates showing up to 15.5 times higher specific activity than commercial Pt / C catalysts. However, the document does not elaborate on the kind of defects that are useful PT / 2025 / 13854 and does not utilize multiple defects to prepare a more advantageous electrocatalyst in an appropriate particle size.

[0013] Therefore, there is a need to develop an electrocatalyst which will be less expensive with good stability and durability. Thus, the inventors of the present invention have successfully addressed the drawbacks of the available literature in high-temperature proton exchange membrane fuel cells.

[0014] To summarize, the inventors of the present invention provides the interaction between platinum and oxygen can be effectively managed by leveraging 2D line defects such as twin and grain boundary defects. One of the most viable approaches to overcome these challenges is to reduce particle size, particularly through in situ alloying. This method offers a practical and scalable solution by depositing particles onto a support material in a single step. As a result, it is highly desirable for various applications and a reliable way to address the issue at hand.

[0015] OBJECTIVES OF THE INVENTION

[0016] An objective of the present invention is to provide an electrocatalyst comprising of platinum- metal alloy enriched with 2D twin and grain boundary defects.

[0017] Another objective of the invention is to provide a process of preparation of said electrocatalyst by hot injection modified polyol method.

[0018] Yet another objective of the invention is to provide a half fuel cell comprising electrocatalyst.

[0019] Yet another objective of the invention is to provide a full fuel cell comprising said electrocatalyst.

[0020] SUMMARY OF THE INVENTION

[0021] In one aspect, the present invention relates to an electrocatalyst for proton exchange membrane fuel cell, comprising: platinum-metal (Pt-M) alloy, on a support material wherein the Pt-M alloy is enriched with two-dimensional (2D) twin and grain boundary defects. PT / 2025 / 13854

[0022] In another aspect, the present invention provides a process of preparation of said electrocatalyst, comprising steps of: a) activating and functionalizing a support material selected from the group consisting of vulcanized carbon, metal oxide, carbon black, and graphite by treating the support with an oxidizing agent at a temperature in the range of 0°C to 5 °C under sonication to obtain a dispersion, followed by heating the dispersion at a temperature in the range of 50°C to 70°C under reflux conditions for a period of 7 to 9 hours to obtain an activated and functionalized support; b) preparing a support dispersion by adding the activated and functionalized support to a mixture of solvents under sonication for 7 to 10 hours, followed by refluxing at a temperature in the range of 160°C to 200°C for 3 to 8 hours to obtain mixture A; c) preparing an alloy dispersion by adding a platinum precursor and a metal precursor, wherein the metal is selected from the group consisting of cobalt, scandium, titanium, iron, nickel, zinc, yttrium, tin, magnesium, molybdenum, palladium, zirconium, iridium, ruthenium, and rhodium, to a mixture of solvents and heating at 70°C for 3 hours under sonication to obtain mixture B; d) heating mixture A to a temperature in the range of 160°C to 200°C in a reflux condenser setup, and injecting mixture B into mixture A, maintaining the reaction for 5 to 10 minutes to induce alloying and the formation of two-dimensional twin and grain boundary defects in the Pt-M alloy; e) filtering and drying the resulting crude electrocatalyst to obtain the electrocatalyst comprising a Pt-M alloy enriched with two-dimensional twin and grain boundary defects, wherein the particle size of the Pt-M alloy is in the range of 0.9 nm to 2.8 nm, and the electrocatalyst is substantially free of metallic impurities and oxide by-products.

[0023] The electrocatalyst of the present invention can be contained in a half-fuel cell along with working electrode, reference electrode, power supply, and electrolyte solution; wherein said electrocatalyst can be coated or decorated onto said working electrode. In another aspect, the electrocatalyst can be contained in a full fuel cell such that the fuel cell comprises: an anode, a cathode, proton exchange membrane, the said electrocatalyst, and gas diffusion layer; wherein said electrocatalyst is coated or deposited onto said gas diffusion layer. PT / 2025 / 13854

[0024] BRIEF DESCRIPTION OF THE DRAWING

[0025] Figure 1 shows HRTEM images of the prepared electrocatalyst samples covering structural features such as defects and boundaries in the metal alloy of said catalyst, wherein the images a, b, and c correspond to Pt3Co(2.3, t,g-b) / fVC-160; images d, e, and f belong to the sample Pt3Co(i.8, t,g-b) / fVC-180; and images g, h, and i correspond to Pt3Co(i.3,t,g-b) / fVC-200. Further, images j, k and 1 show particle size distribution histograms for Pt3Co(2.3, t,g-b) / fV C- 160, Pt Coi i ,s. t,g-b) / fVC-180 and Pt3Co(i.3,t,g-b) / fVC-200, respectively, and images m, n and o show inverse FFT images of the samples, respectively.

[0026] Figure 2 shows HRTEM images of the prepared electrocatalyst samples covering atomic features and depth of the metals contained in the catalyst wherein images a (ai, a2, as), b, and c correspond to Pt3Co(2.3, t,g-b) / fVC-160; images d (di, d2, ds), e, and f belong to the sample Pt3Co(i.8, t,g-b) / fVC-180 and g (gi, g2, g3), h, and i corresponds to Pt3Co(i.3,t, -b) / fVC-200; Here, the images a, d and g covers raw metals’ bulk mapping, wherein a (including al to a3) covers 30 nm resolution image, d (including dl to d3) covers 50 nm resolution image, and g (including gl to g3) covers 10 nm image; and specifically al, dl and gl cover Pt metal mapping, a2, d2 and g2 cover Co metal mapping, and a3, d3 and g3 cover mixed PtCo metal alloy mapping; images b, e and h show HRTEM line analysis; and images c, f and i show spot EDX.

[0027] Figure 3 shows (a) PXRD graph of all the prepared electrocatalyst samples, (b) Raman analysis of of all the prepared electrocatalyst samples, (c) BET pore distribution of all the prepared electrocatalyst samples, (d) XPS spectra of Pt(4f), (e) VB-XPS of of all the prepared electrocatalyst samples, and (f) TGA analysis of the sample Pt3Co(i.3,t, -b) / fVC-200.

[0028] Figure 4 shows electrochemical analysis of the all the prepared electrocatalyst samples in comparison with the state-of-the-art catalyst Pt / C (JM - Johnson Matthey), where it provides: (a) CV analysis at 50mVs-1N2saturated 0.1M HCIO4, (b) magnified region of hydrogen desorption, (c) magnified region for Pt-0 reduction, (d) LSV atlOmVs'Hn O2 saturated 0.1 M HC1O4, (e) Tafel analysis, (f) Kinetic current, (g) mass activity, (h) specific activity, and (i) K- L analysis for n value.

[0029] Figure 5 shows ADT analysis have been performed for the sample Pt3Co(2.3, t,g-b) / fVC-160 as indicated in (a) & (d), the sample Pt3Co(i.s,t,g-b) / fVC-180 in (b) & (e), and the sample Pt3Co(i.3, t,g-b) / fVC-200 in (c) & (f). PT / 2025 / 13854

[0030] Figure 6 shows (a) test station used for testing said electrocatalyst in HTPEMFC and LTPEMFC, (b) HTPEMFC testing in Hi-Air and H2-O2, (c) kinetic current, (d) tafel analysis, (e) solid state Cyclic voltammogram, (f) LTPEMFC testing for catalyst in H2-Air, (g) kinetic current plot, (h) tafel analysis, and (i) solid state cyclic voltammogram; Here the images (b) to (e) refer to testing and analysis of HTPEMFC, and the images (f) to (i) refer to testing and analysis of LTPEMFC.

[0031] Figure 7 shows stability test of the catalyst in the HTPEMFC with H2-Air feed.

[0032] DETAILED DESCRIPTION OF THE INVENTION

[0033] The present invention is directed towards an electrocatalyst comprising a platinum-metal (Pt- M) alloy enriched with two-dimensional (2D) twin and grain boundary defects. These structural features are engineered to optimize the interaction between platinum and oxygen intermediates, thereby enhancing ORR kinetics and improving both activity and durability. The electrocatalyst is prepared by novel hot injection modified polyol method, which enables precise control over particle size and the introduction of 2D defects. This method ensures uniform alloying of platinum with the secondary metal (M), selected from a range of transition metals, while avoiding the formation of metallic impurities or oxide by-products. The resulting electrocatalyst demonstrates a high ECSA, improved stability over extended cycles, and enhanced performance in both low-temperature and high-temperature PEMFCs.

[0034] Here, the obtained alloy catalyst is named as PcCo (nm, t,g-b) / fVC-160, 180, 200 where nm specifies particle size and t,g-b indicating twin and grain boundary defects. Here, the HTPEMFC refers to high temperature proton exchange membrane fuel cell, and LTPEMFC refers to low temperature proton exchange membrane fuel cell.

[0035] In an embodiment, the present invention relates to an electrocatalyst for a proton exchange membrane fuel cell, comprising: a platinum-metal (Pt-M) alloy, on a support material wherein the Pt-M alloy is enriched with two-dimensional (2D) twin and grain boundary defects.

[0036] In an embodiment, the metal in said alloy is selected from but limited to cobalt, scandium, titanium, iron, nickel, zinc, scandium, yttrium, scandium, tin, magnesium, molybdenum, PT / 2025 / 13854 palladium, zirconium, iridium ruthenium, and rhodium. In a preferred embodiment, the metal in said alloy is not platinum. The support material is selected from but not limited to vulcanized carbon, metal oxide, carbon black, and graphite. In a preferred embodiment, the support material is functionalized Vulcan XC-72 carbon.

[0037] In another embodiment, the atomic percentage of platinum in said alloy of the electrocatalyst is in the range of 72 to 82 %. In another embodiment, the atomic percentage of metal (M) in said alloy of the electrocatalyst is in the range of 20 to 28 %.

[0038] In another embodiment, the particle size of platinum is in the range of 0.9 to 2.8 nm.

[0039] The electrocatalyst is substantially free of metallic impurities and oxide by-products. In an embodiment, the Pt-M alloy of the electrocatalyst is a platinum-cobalt alloy.

[0040] In another embodiment, the electrocatalyst has increased D band centre in said alloy material.

[0041] In another embodiment, there is presence of 2d line defects in the planes of Pt, for instance, 2D twin and grain boundary defects. In a preferred embodiment, there is no 3d defects in Pt. In some embodiments, the two-dimensional twin and grain boundary defects are present predominantly in the (111) crystallographic planes of platinum.

[0042] In another embodiment, the content or amount of said metal (M) in said alloy of electrocatalyst is in the range of 8.3 to 10.3 mass %, and the rest to make 100 mass% is platinum.

[0043] In another embodiment, the electrocatalyst comprises fewer angles between twin boundaries leading to effective catalyst having better activity and stability for more cycles. In another embodiment, the electrocatalyst comprises modulation of angle between twin pair in the twin boundary defects which helps in increasing the strain, creating feasible kinetics.

[0044] In another embodiment, the metal (M) is incorporated in platinum planes leading to the compressive strain, resulting in an approximate 0.9° shift in platinum (111) planes.

[0045] In another embodiment, the electrocatalyst does not contain any metallic impurity or oxide side product, confirming the homogeneity and nearly 100% alloying of Pt with M without any impurities of the base metal. PT / 2025 / 13854

[0046] The process of preparation of the electrocatalyst is done via a hot injection modified polyol method, hydrothermal method or microwave method, for inducing twin and grain boundary defects in said electrocatalyst.

[0047] In another embodiment, the present invention provides a process of preparation of said electrocatalyst, comprising steps of: a) activating and functionalizing a support material selected from the group consisting of vulcanized carbon, metal oxide, carbon black, and graphite by treating the support with an oxidizing agent at a temperature in the range of 0°C to 5°C under sonication to obtain a dispersion, followed by heating the dispersion at a temperature in the range of 50°C to 70°C under reflux conditions for a period of 7 to 9 hours to obtain an activated and functionalized support; b) preparing a support dispersion by adding the activated and functionalized support to a mixture of solvents under sonication for 7 to 10 hours, followed by refluxing at a temperature in the range of 160°C to 200°C for 3 to 8 hours to obtain mixture A; c) preparing an alloy dispersion by adding a platinum precursor and a metal precursor, wherein the metal is selected from the group consisting of cobalt, scandium, titanium, iron, nickel, zinc, yttrium, tin, magnesium, molybdenum, palladium, zirconium, iridium, ruthenium, and rhodium, to a mixture of solvents and heating at 70°C for 3 hours under sonication to obtain mixture B; d) heating mixture A to a temperature in the range of 160°C to 200°C in a reflux condenser setup, and injecting mixture B into mixture A, maintaining the reaction for 5 to 10 minutes to induce alloying and the formation of two-dimensional twin and grain boundary defects in the Pt-M alloy; e) filtering and drying the resulting crude electrocatalyst to obtain the electrocatalyst comprising a Pt-M alloy enriched with two-dimensional twin and grain boundary defects, wherein the particle size of the Pt-M alloy is in the range of 0.9 nm to 2.8 nm, and the electrocatalyst is substantially free of metallic impurities and oxide by-products.

[0048] In an embodiment of the process, the atomic ratio of platinum to metal M in the alloy is approximately 3:1. PT / 2025 / 13854

[0049] In some embodiments, the platinum precursor and the metal precursor are selected from acetylacetonate, acetate, or nitrate salts. The mixture of solvents used in the process can comprise at least two alcohol-based solvents and at least one amide solvent. In some embodiment, the mixture of solvents comprises ethylene glycol, 1 -heptanol, and N,N- dimethylformamide in a volume ratio of 5:2: 1.

[0050] In another embodiment, the particle size of platinum in said alloy material (PtM) of the electrocatalyst is controlled by the temperature range as covered in step d) i.e., 160 to 200 C. Specifically, the particle size of platinum is in the range of 1 to 1.3 nm when the process step d) is done at 200 C; the particle size of platinum is in the range of 1.6 to 2.0 nm when the process step d) is done at 180 C; and the particle size of platinum is in the range of 2.1 to 2.6 nm when the process step d) is done at 160 °C.

[0051] In another embodiment, the temperature of process step d) should not go above 200 C as it creates problem in making of material and also changes the structural features of the electrocatalyst, making it undesirable. However, it is noted that by changing solvent, the temperature can go beyond 200 °C.

[0052] In another embodiment, the support material used in step a) is selected from but limited to vulcanized carbon, metal oxide, carbon black, and graphite. In another embodiment, the mixture of solvents comprises mixture of at least two alcohol based solvents, and at least one amide solvent.

[0053] In another embodiment, the polyol solvents are selected from but not limited to ethylene glycol (EG), heptanol, hexanol, oleylamine, dimethyl formamide and so on. In another embodiment, the amide solvent is selected from but not limited to N, N dimethyl formamide (DMF), and so on. In another embodiment, the at least two alcohol solvents and at least one amide solvent (making 3 solvents mixture) is used in a ratio of 4-7: 1-4: 0.5-3 (1stalcohol solvent: 2ndalcohol solvent: amide solvent). In another embodiment, the at least two alcohol solvents and at least one amide solvent (making 3 solvents mixture) is used in a ratio of 5:2: 1 (1stalcohol solvent: 2ndalcohol solvent: amide solvent).

[0054] In another embodiment, the metal in said alloy is selected from but limited to cobalt, scandium, titanium, iron, nickel, zinc, scandium, yttrium, scandium, tin, magnesium, molybdenum, palladium, zirconium, iridium ruthenium, and rhodium. PT / 2025 / 13854

[0055] In another embodiment, the precursor of platinum used in step c) is based on acetyl acetonate, acetate, nitrate and so on. In another embodiment, the precursor of metal used in step c) is based on acetyl acetonate, acetate, nitrate and so on.

[0056] In another embodiment, the washing of step e) is done using cold and hot water. In another embodiment, the washed electrocatalyst material is filtered and the residue is dried in a vacuum of 0.2 bar at temperature in the range of 100 to 120 °C.

[0057] By utilizing the distinct characteristics of 2D twin and grain boundary defects, the described approach achieves a notable reduction in the interaction strength between platinum and oxygen intermediates, thereby enabling faster reaction kinetics. Furthermore, the inclusion of the secondary metal induces compressive strain in the platinum lattice, which contributes to improved catalytic activity. This process also facilitates the adjustment of particle size, with reduced particle dimensions demonstrating enhanced catalytic activity and stability. These developments collectively tackle persistent challenges in PEMFC technology, providing a costefficient, durable, and high-performance solution for clean energy applications.

[0058] The electrocatalyst of the present invention can be contained in a half-fuel cell along with working electrode, reference electrode, power supply, and electrolyte solution; wherein said electrocatalyst can be coated or decorated onto said working electrode. In another aspect, the electrocatalyst can be contained in a full fuel cell such that the fuel cell comprises: an anode, a cathode, proton exchange membrane, the said electrocatalyst, and gas diffusion layer; wherein said electrocatalyst is coated or deposited onto said gas diffusion layer.

[0059] In another embodiment, the present invention relates a half-fuel cell comprising: i. said electrocatalyst, ii. working electrode, iii. reference electrode, iv. power supply, and v. electrolyte solution; wherein said electrocatalyst is coated or decorated onto said working electrode. PT / 2025 / 13854

[0060] In another embodiment, the half fuel cell is half proton exchange membrane fuel cell.

[0061] In another embodiment, the working electrode is selected from but not limited to glassy carbon, gas diffusion layer, carbon cloth, nickel foam, carbon paper and so on. In another embodiment, the reference electrode is selected from but not limited to Ag / AgCl electrode, Hg / HgO electrode, Hg / HgSCh electrode and so on. The selection of reference electrode is depending upon the medium used in which testing is done, e.g. for HC1 or HCIO4 acid, the Ag / AgCl is used, for base, it is Hg / HgO, and for H2SO4, it is Hg / HgSC , and few more based on pH and medium.

[0062] In another embodiment, the reference electrode is selected from but not limited to HCIO4, KOH, NaOH, H2SO4, H3PO4 and so on.

[0063] In another embodiment, the present invention provides a full fuel cell comprising: i. an anode, ii. a cathode, iii. proton exchange membrane, iv. said electrocatalyst, and v. one or more gas diffusion layer(s); wherein said electrocatalyst is coated or deposited onto said gas diffusion layer(s).

[0064] In another embodiment, the gas diffusion layer is placed between the anode and the proton exchange membrane. In another embodiment, the gas diffusion layer is placed between the cathode and the proton exchange membrane.

[0065] In another embodiment, the proton exchange membrane is selected from but not limited to fluoropolymer such as sulfonated tetrafluoroethylene -based fluoropolymer-copolymer (Nafion), sulfonated polyether ether ketones, polyarylene ethers, poly sulphones, polyimides and so on.

[0066] In another embodiment, the anode is selected from but not limited to combination of carbon support gas diffusion layer and said metal alloy nanoparticles. In this regard, the carbon support can be selected from normal vulcan carbon to ketjan black to other 2d and 3d derived carbon PT / 2025 / 13854 support such as nanowire nanotubes and 3D sponges, etc. In metal alloy NPs, instead of cobalt other metals such as nickel, iron, tin, tungsten, tantalum, zirconium, molybdenum and gallium can be used.

[0067] In another embodiment, the cathode is selected from but not limited to combination of carbon support gas diffusion layer and metal alloy nanoparticles. In this regard, the carbon support can be selected from normal vulcan carbon to ketjan black to other 2d and 3d derived carbon support such as nanowire nanotubes and 3D sponges, etc. In metal alloy NPs, instead of cobalt other metals such as nickel, iron, tin, tungsten, tantalum, zirconium, molybdenum and gallium can be used.

[0068] In another embodiment, the gas diffusion layer(s) is / are made of or selected from but not limited to engraved and stamped flow field GDL, carbon cloth, carbon paper, and metal foam.

[0069] The electrocatalyst of the present invention is provided with a platinum-based alloy enriched with 2D twin and grain boundary defects. It is noted that 2D defects and particle size control gave not only an increased ECSA of 84 m2mg-1of Pt but also provided a stable catalyst for 20

[0070] K cycles of ADT with a loss of only 4 % and negligible loss in mass activity and specific activity. The twinning of (111) planes of platinum with a high degree of strain not only helped get high onset, El / 2 and limiting current of 0.98 V, 0.856 V but also -6.0 mAcm-2 compared to Pt / C having 0.91 V 0.817 V and -5.57 mAcm-2 its significance have been proven through DFT analysis. Performing an HTPEFC testing with the desired catalyst at 45 cm2gave a 25% more current response i.e. 53 A compared to 42 A for Pt / C in oxygen. The lightest performed at 22 A in the air for more than 27 hours showing only a 1 mV drop in potential.

[0071] From DFT analysis, the role of particle size and the strained (111) were understood to shift the D band centre of the catalyst weakening the Pt-O* interaction and resulting in faster kinetics. Further the catalyst shows 33% higher ECSA (84m2mg_1pt) and was also found to be highly stable for 20000 cycles. Subsequent device testing has been performed and analyzed its activity for HT-PEMFC at an area of 45 cm2both in air and oxygen where it surpasses the Pt / C catalyst by a definite margin 1.18 Acm-2and 0.51 Acm-2in air and oxygen, respectively. Notably, the catalyst-maintained stability at 22 A in device under air for 1600 minutes with no loss in voltage.

[0072] In an embodiment the present invention relates to an Pt-M alloy electrocatalyst that is durable due to its electrochemical performance, structural integrity, and catalytic activity over extended PT / 2025 / 13854 operational cycles and prolonged periods under the harsh acidic and oxidative conditions typical of proton exchange membrane fuel cells (PEMFCs). Specifically, the durability is demonstrated by: Minimal loss in electrochemically active surface area (ECSA) after accelerated durability testing (e.g., less than 5% loss after 20,000 cycles); negligible decrease in mass activity and specific activity after repeated cycling; Stable current and voltage output during continuous operation (e.g., less than 2 mV voltage drop after 27 hours at high current density); Preservation of the catalyst’s nanostructure, including the retention of 2D twin and grain boundary defects, and the absence of significant particle agglomeration or dissolution; resistance to degradation mechanisms such as Pt leaching, agglomeration, and the formation of Pt-Ox species.

[0073] In yet another embodiment, the present invention relates to an Pt-M alloy electrocatalyst that is stable retain its structural, compositional, and electrochemical properties under continuous operation and repeated cycling in the harsh acidic and oxidative environment of proton exchange membrane fuel cells (PEMFCs). Specifically, stability of the present electrocatalyst is characterized by maintenance of particle size and distribution, with minimal agglomeration or growth of alloy nanoparticles over time; preservation of the engineered 2D twin and grain boundary defects within the Pt-M alloy structure, sustained electrochemically active surface area (ECSA) and catalytic activity (mass and specific activity) after prolonged operation and accelerated stress testing, resistance to dissolution, leaching, or segregation of the alloying metal (M) from the platinum matrix, consistent performance metrics, such as current density and voltage output, with negligible degradation during extended fuel cell operation (e.g., less than 2 mV voltage drop after 27 hours at high current density) and absence of significant formation of metallic impurities.

[0074] EXAMPLES:

[0075] Platinum (II) acetylacetonate, cobalt (III) acetylacetonatel -heptanol (1H), potassium hydroxide (KOH), and Polytetrafluoroethylene (PTFE) were procured from Sigma Aldrich. Ethylene glycol (EG), N, N dimethyl formamide (DMF), perchloric acid, isopropyl alcohol, and hydrogen peroxide were purchased from Thomas Baker, Gas diffusion layer- 38BC (GDL) from Sigracell®, 5% and 20% aqueous solutions of Nafion, from Electrochem and Ion Power respectively, for performing the HTPEMFC testing polybenzimidazole (PBI) membrane (Fumapem) was used. All chemicals were analytical grade and were used without further purification. PT / 2025 / 13854

[0076] Example 1: Preparation of electrocatalyst 1’t Co alloy supported onto fVC; (Working

[0077] Example)

[0078] Step A = Preparation of functionalized Vulcan XC-72 carbon (fVC) as functionalized support: In this process, 1 g of Vulcan XC-72 substrate was subjected to treatment with 200 ml of 30%, hydrogen peroxide (H2O2) at 60 °C under reflux conditions for 8 h, utilizing a condenser. Initially, the carbon substrate was gradually introduced to the peroxide at 0-5 °C, followed by sonication to ensure thorough dispersion of the particles within the solution. The subsequent treatment at 60 °C for 8 h facilitates the generation of surface functional groups, serving as anchoring sites for the dispersion of metals. The resultant product obtained postreflux treatment was collected via filtration and thoroughly washed with ample amounts of water. The product obtained after drying in an oven at 80 °C for 8 h is designated as fVC, wherein, ‘f signifies ‘functionalization’.

[0079] Step B: Preparation of PtsCo alloy on fVCvia the hot-injection method: In this newly introduced hot-injection method, the metal precursor dissolved in the solvent mixture at a particular temperature was directly injected into another solvent mixture containing the carbon support material maintained at an elevated temperature. Precisely, in the present study, a solvent mixture comprising EG, DMF, and 1 -heptanol was homogenized in a proportion of 5:2: 1, followed by the addition of KOH (1 g). Subsequently, this mixture was divided into two portions in the volume ratios of 3:1. Mixture A, containing the three-fourth portion of the solvent mixture was combined with fVC followed by sonication and overnight stirring to ensure dispersion of the carbon substrate in the solvent mixture. This mixture was then subjected to refluxing at 160 °C, 180 °C, and 200 °C. Mixture B, containing one-fourth portion, was heated to 70 °C in which the metal precursors were added in the pre-decided ratio to obtain the PtsCo. The homogenized solution of Mixture B was then injected into the hot solution of Mixture A, where EG will provide the reducing atmosphere as per the well-known polyol process; DMF will assist it in facilitating simultaneous reduction of both the metals namely Pt and Co. After the addition of Mixture B to Mixture A, the reflux was continued for 4 h under the same condition. Subsequently, the reaction mixture was cooled down and the filtered wet cake was alternatively washed with cold and hot water and dried in a vacuum of 0.2 bar at 110 °C. Thus obtained alloy catalyst is named as PtsCo (nm, t,g-b) / fVC-160, 180, 200 where nm specifies particle size and t,g-b indicating twin and grain boundary defects.

[0080] Example 2: Analysis and Characterization of prepared electrocatalyst material: PT / 2025 / 13854

[0081] Physical characterization of the obtained electrocatalyst:

[0082] (1) FESEM analysis of microstructure

[0083] The micro structure of the catalyst was investigated with the help of FESEM. The FESEM images were recorded with the help of a FEI Nova Nano SEM 450 FESEM microscope. The samples for FESEM were prepared by thin coating in isopropyl alcohol (IPA) -dispersed sample (5 mg of the sample in 5 ml IPA) on a silicon wafer and dried for 30 minutes under an IR lamp to remove IPA. The HRTEM images were recorded using a JEOL JEM F-200 HRTEM instrument with a point-to-point resolution of 0.19 nm. The samples for the HRTEM analysis were prepared over a carbon-coated 200 mesh copper grid by drop-coating the well-dispersed sample in isopropyl alcohol (1.0 mg of the sample in 5 mL solvent). The sample-coated HRTEM grid was properly dried for 2 h under an IR lamp.

[0084] (2) PXRD analysis of crystal structure

[0085] To check the crystal structure of the as-synthesized samples, powder X-ray diffraction (PXRD) analysis was done. The XRD investigation was carried out on a Rigaku Smart Lab diffractometer with Cu Ka radiation ( = 1.5406 A) in the 29 range of 10 to 80° with a scan rate of 5° min1. The nitrogen (N2) adsorption-desorption isotherm was recorded on a Quantachrome-Quadrasorb automatic volumetric instrument to analyze the pore volume and the surface area of the samples. The XPS measurement was performed using a monochromatic small spot XPS system, specified with an X-ray monochromator source by the 1800 doublefocusing hemispherical analyzer- 128-channel detector and micro-focused Al Ka. Raman spectral interpretation was carried out using a 632 nm green laser (NRS 1500W) on an HR 800 RAMAN spectrometer. The loading of the active component over the carbon support was measured using an SDT Q600 DSC-TDA thermo-gravimetric (TG) instrument at room temperature to 900 °Cat a fixed heating rate of 5 °C min1under an air atmosphere.

[0086] (3) Particle Size

[0087] As discussed in the synthesis procedure, hot injection was carried out at varying temperatures ranging from 160 °C to 200 °C, with intervals of 20 °C. The images in Figure 1 have been categorized into three distinct sections corresponding to the temperature of hot injection denoted as Figure 1 (a, b and c), (e, f, and g) and (i, j and k) for 160, 180, 200 °C hot injected respectively. These images elucidate the dispersion of particles at the nanometer scale, serving PT / 2025 / 13854 as the basis for calculating the particle size distribution, as depicted in the corresponding figures (Figure 1, j, k and 1). The underlying hypothesis suggests that an increase in temperature increases the rate of reduction, resulting in accelerated reduction kinetics, thereby limiting the time available for particle growth. The data corroborates this assertion, revealing a reduction in particle size from 2.7 ± 0.27 nm at 160 °C, to 1.8 ± 0.32 nm at 180 °C, and further down to 1.3 ± 0.2 nm at 200 °C ( Figure 1 - j, k, and 1).

[0088] The linear correlation observed between the decrease in particle size and the temperature of hot injection constitutes an interesting observation, complemented by the uniform dispersion observed through the polyol reduction process, reduction initiates nucleation, followed by growth in the solution phase before eventual embedding to the carbon support. Elevating the temperature of hot injection limits the growth of particles and controls the kinetics.

[0089] In addition to curbing the growth of particles, hot injection also influences the alignment of particles in the preferred orientation inducing structural defects. This is arising from the limited time available for seeding followed by particle growth. The manifestation of this misalignment is evident in the form of 2D line defects in the system, viz; twin and grain boundary defects. Appearance of 2D defects across all samples provides gravity to the importance of hot injection assisted modified polyol process (Figure 1 - b, c, e, f, h and i) respectively for 160 °C, 180 °C, and 200 °C hot injection. The relevancy of this process to yield controlled sub 1.3 nm particle size enriched with defects in platinum cobalt alloy samples directly on carbon support is axiomatic in itself. To ascertain that the defects creation was primarily because of hot injection, inventors prepared a sample of PtsCo / fVC without hot injection which not only exhibited an increased particle size averaging about 2.7 nm but also displayed the absence of 2D defects. Upon examining the nature of twin boundaries concerning the angles among the twin pair, it could be seen that the sample prepared at 160°C showed defects in the (200) planes of PtsCo, with a d spacing of 0.189 nm having an angle of 140° (Figure lb). Similarly, the sample prepared at 180°C displayed a comparable angle of 135°and d-spacing corresponding to the (200) and (211) alloyed planes (Figure le). Notably, in the case of a 200 °C hot injected sample, the angle of the twin boundary was found to drop to 1110while in some instances even as low as 68°, defects were in the PtsCo (111) planes, characterized by d-spacing of 0.221 nm (Figure Ih). Defects in platinum planes hinder the coordination atmosphere of oxygen on platinum subsisting their interaction by modulating coordination number, thereby enhancing the kinetics of the ORR. Defects in the form of twin boundaries in the (111) plane show highly PT / 2025 / 13854 stained evidence from a reduced angle. The fact that this plane is well known for strongly binding OOH*, OH* intermediate, impeding the reaction kinetics, the observed defects will certainly curtail this interaction rendering a facile reaction pathway. Furthermore, besides, the twin boundaries, the entire system exhibited an abundance of grain boundary defects. Grain defects are recognized for enhancing the catalytic power of platinum alloys (Figure 1 - c, f, and i). To facilitate a deeper understanding of these defects (Figures 1 - m, n and o) depicting inverse Fast Fourier Transforms (FFT) are also provided.

[0090] (4) Uniform Distribution

[0091] Mapping of particles exhibiting the presence of platinum and cobalt metals invariably across the surface (Figure 2 a (ai, a2 and as), d (di, d2 and ds) and g (gi, g2 and gs)). The continuity of both elements is evident throughout the samples for both the elements platinum and cobalt. Supplementing the mapping line analysis where carried, which renders the presence of elements at different depths (Figure 2 - b, e, and h). The presence of both Pt and Co lines validates uniformity throughout samples.

[0092] The intensity of platinum being higher than cobalt is attributed to the fact that platinum is thrice that of cobalt atomically along with that the attenuation factor of platinum is higher than cobalt. A more distinct proof pertaining to platinum and cobalt presence has been inferred from spot EDX (refer, Figure 2 - c, f, and i), and their atomic and weight ratio also provided in the table as provided below:

[0093] Table 1: PT / 2025 / 13854

[0094] The atomic ratio of platinum oscillates between 76.78, 79.98 and 72.47 %, while cobalt vacillates from 23.22, 20.02, and 27.53 at 160, 180, and 200 °C hot injected samples, distinctly conforming atomic ratio of platinum to cobalt being approx. 3: 1. In inference, inventors concluded that homogeneously alloyed defects induced and particle size have been prepared through hot injection-assisted modified polyol process.

[0095] (5) PXRD analysis of the grain defects

[0096] Beginning with the confirmation of alloy presence in all the samples, powder X-ray diffraction (PXRD) have been recorded as shown in Figure 3a, which is compared with the JCPDS of PtsCo (00-029-0499) and that of Pt (00-004-0802). The strained created due hot injection, as observed through HRTEM, twin and grain defects, also have their implication on the XRD profile. As inventors move from 140 to 200 °C, having a shift toward higher 20 values, conforming the compressive strain in the system for incorporation of cobalt in platinum matrix. The incorporation of cobalt in platinum planes leads to this compressive strain, resulting in an approximate 0.8° shift in platinum (111) planes for all the samples. Peaks start to get broaden as it moves from lower to higher temperature of hot injection, attributed to steady and continuous decrease in particle size, for particle less than 2 nm, the diffraction pattern significantly deviate. Thus, there is a close agreement between HRTEM particle size analysis at the nano-level and PXRD’s characterization of the bulk nature of the platinum alloy catalyst. The absence of any metallic or oxide cobalt peaks indicates that this method delivers complete homogeneity and nearly 100% alloying without any impurities of the base metal. The effect of smaller particle size can be seen through the Brunauer-Emmett-Teller (BET) pore size distribution analysis as well, where the pores less than 2 nm decreases as the temperature of PT / 2025 / 13854 hot injection increases. The decrease is attributed to the fact that smaller, well-distributed particles can block these pores. The intensity for the sample hot injected at 200 °C has dropped drastically, as the particles size averaged 1.3 nm. A similar behaviour is observed through Raman analysis where the Id / Ig ratio decreases from 1.097 Pt3Co(2.7, t,g-b) / fVC-160 to 1.065 for Pt3Co(i.8,t,g-b) / fVC-180 and finally to 1.060 for final catalyst Pt3Co(i.3. t.g-b) / fVC-200, indicating a decrease in defects in Figure 3b and 3c.

[0097] Moving further from the structural analysis and probing into the electronic changes happening in the platinum system, a detailed analysis of X-ray photoelectron spectroscopy (XPS) has been caried out. In all the samples, there was a clear evidence of electron transfer from platinum to cobalt. As shown in Figure 3d, the Pt° 413 / 2 peak has shifted from 71.2 eV to 72.12 eV in the case of Pt3Co(i.3, t.g-b) / fVC-200, and the Pt° 4fs / 2 peak has shifted from 74.50 eV to 75.54 eV, compared with the Pt / C. The shifting of electron density from platinum to cobalt has significant role in stabilization of cobalt in harsh acidic corrosive environment. Along with this the decreased electron density on platinum weakens the interaction of platinum with intermediates involve in ORR creating a condition favorable for feasible kinetics. The same can be seen in the valance band spectra of samples where the d band center of the catalyst moves to higher binding energy as the temperature of hot injection is increased (Figure 3e). This analysis goes hand in hand with the HRTEM XRD and XPS results. Finally, the loading of the catalyst was confirmed through TGA analysis the the catalyst was heated in air atmosphere to 900 °C resulting in burning of carbon and leaving the metal behind. That has shown the platinum cobalt alloy in nearly 40 % by weight (Figure 3f).

[0098] (6) Electrochemical characterization:

[0099] For the characterization of the catalyst for their electrochemical single electrode studies, a Biologic VMP3 electrochemical workstation was used. The half-cell studies namely cyclic voltameter (CV), linear sweep voltameter (LSV), accelerated durability test (ADT) and accelerated stress test (AST) were carried out. The percentage peroxide produced as a result of the parasitic 2-electron transfer ORR process was quantified by using a rotating ring disc electrode (RRDE) apart from this with the help of rotating disc electrode (RDE) single electrode performance and the Koutecky-Levich (KL) plots were obtained. All these studies were performed with 0.1M HCIO4 as the electrolyte. The catalyst-coated Pine glassy carbon was used as the working electrode, graphite as the counter electrode, and Ag / AgCl as the reference electrode. The voltage correction to the RHE scale was done by using the equation: PT / 2025 / 13854

[0100] ERHE = EAg / Agci + 0.196 + 0.596 pH. In the preparation of the catalyst ink for the half-cell studies, preciously, 5 mg of the catalyst was first dispersed in IPA and water with a volume ratio of 3:2; subsequently, 5% Nafion solution in water was added into the mixture by maintaining a Nafion / Carbon (N / C) ratio of 0.66. This mixture was then degassed and sonicated to obtain a uniform and consistent ink for an hour. The prepared ink was then coated on the glassy carbon electrode having an area of 0.196 mm2. CV profiles were recorded at a scan rate of 50 mVs1without rotation in the potential range of 0.0 to 1.3 V vs RHE. This graph was used for the calculation of the electrochemically active surface area (ECS A) of Pt from the hydrogen adsorption and desorption regions, the area of the Pt-0 peak was also calculated from here. The LSV profiles were recorded in a cathodic scan in the region from 1.0 V to 0.0 V vs RHE at a scan rate of 10 mVs1and 1600 rpm rotation. The LSV profile gives information about the limiting current (II) of the catalyst and about its onset and half-wave potentials which are the important performance indicators in determining the intrinsic activity of the catalyst. The RRDE studies were performed in the same medium where the ring and the disc current measurement helped us to understand the dominant reaction pathway among the two possible routes involving the 2- and 4-electron transfer processes. KL analysis has been performed at different rotations from 400 to 2400 RPM.

[0101] (7) Electrochemical three electrode (Half fuel cell) analysis was performed to compare different catalyst with state-of-the-art Pt / C(40%). The methodology for preparing the catalyst ink for testing and the experimental procedures are elaborately discussed below:

[0102] Preparation of Membrane electrode assembly (MEA) and device testing LTPEMFC:

[0103] A Decal method based on bar coating was used for preparing the MEA. A catalyst ink was first prepared using a mixture of solvents namely water, ethanol, propylene glycol, nafion solution, and catalyst itself. Here permuting the ratio of ionomer (Nafion) to carbon ratio (n / c) the interface or the triple phase boundary can be exploited for betterment. In the present case, the n / c value was been varied from 0.5 to 1.0 out of which 0.9 n / c gave the best possible interface. The preparation of ink undergoes a series of sonication, degassing to probe sonicating then again degassing for 0.5, 0.5, 1, and 0.5 hr respectively resulting in consistent slurry for coating. Degassing and probe sonication both are done in ice bath temperatures ranging between 5 to 100C. A bar coater was used to coat the prepared ink on a Teflon sheet of 100-micron thickness known as catalyst-coated teflon (CCT). The prepared CCT is first air dried and then dried in an oven for 8 hr at 1200C. The preparation of catalyst transfer membrane (CTM) was done PT / 2025 / 13854 where the desired dimension of CCT was first cut precisely following which the membrane was sandwiched between the two CCT and hot pressed at 1 ton to transfer catalyst on the membrane. In this process, due to heat the polymer in the catalyst layer and membrane soften and bind together which helps in the transfer of the catalyst layer onto the membrane from teflon. The prepared assembly is then known as CTM. The preparation of membrane electrode assembly was done in a similar way as that of CTM except here CTM was sandwiched between gas diffusion layers (GDL) namely 36 BB from SGL and at a temperature of 130 °C but without load just the contact was maintained here. A 25 cm2fixture was used for testing which was procured from Fuel cell stores having a serpentine flow field for reactant. The prepared MEA is then placed inside of the fixture and compressed by applying torque ensuring proper contact of MEA and flow field of the graphite plate of the fixture.

[0104] (8) Effect on ESCA

[0105] One critical aspect of this study was to not sacrifice the ECSA of the catalyst while achieving alloying characteristics, as evident from the detailed CV analysis. Alloying was observed to decrease the ECSA of the catalyst, as shown by the PtsCo alloyed without hot injection, with an ECSA of 40 m2mg' ’pi. Thus, maintaining ECSA for Pt-H and Pt-0 interaction was one of the primary objectives of this study. It was found that with hot injection, the trend was reversed, indicating that Pt-H and Pt-0 interactions improved compared to normal Pt / C, as shown in (Figure 4 - a, b, and c). All the test were performed in 0.1 M HCIO4 medium catalyst Pt3Coi.3(t,g-b) / fVC-200 has shown the highest ECSA of 84 m2mg-1ptwhile for the sample prepared at 160 °C, and 180 °C were having 60.4 m2mg-1ptand 62.3 m2mg-1pt, respectively. The increase in ECSA with increasing temperature of hot injection can be attributed to the gradual decrease in particle size from 2.7nm to 1.8nm, and finally to 1.3 nm. Still there is a sudden twitch in ECSA moving from 180 to 200 °C hot injection which was carefully analysed in Figure 4b, and 4c dealing with Pt-H interaction and Pt-0 interaction. As from the HRTEM analysis, a clear distinction among PtsCoqj, t,g-b) / fVC-200 where the increased strain in the (111) plane and others showing in (200) plane (Figure 4b) showing the magnified region of hydrogen desorption. It’s known that Pt has a characteristic peak at 0.12 V for 111 plane and a peak at 0.24 V pertaining to the 100 / 111 plateau. Thus, as the particle size decreases the exposure of plain is certain to increase but the drastic change in current for the H adsorption and desorption can be related to the dominance defects in (111) plane for sample injected at 200 °C. The steeper the Pt-0 peak, and faster the kinetics of ORR becomes, and the increased PT / 2025 / 13854 area of the peak directly impacts the overall performance of the catalyst in N2 atmosphere. To assess the impact of all the fine-tuned parameter, linear sweep voltammentry (LSV) experiments were conducted, as depicted in Figure 4d. The onset potential of the various catalyst prepared were in the order of 0.91, 0.91, 0.95, 0.98 V vs. RHE for Pt / C hot injected samples at 160 °C, , 180 °C, 200 °C, respectively. Meanwhile the half wave potential (E1 / 2) values followed the same order for the samples, measuring 0.816, 0.815, 0.830 0.854 V vs. RHE respectively. Furthermore, the limiting current of the Pt3Co(t,g-b) / fVC-200 -6.0 mA cm'2. The leap in the performance of Pt3Co(t,g-b) / fVC-200 can be attributed to a combination of factors, including particle size, 2D defects (twin and grain), and electronic transitions happening between cobalt and platinum. The Tafel slope analyses for all the samples, presented in Figure 4e, yielded values of 74.87 mVdec1, 62.1 mVdec1and 59.8 mVdec1for sample injected at 160 °C 180 °C, and 200 °C , respectively, compared to Pt / C, which exhibited a value of 66.48 mVdec1. This proves the presence of faster kinetics on defect rich sub 1.3 nm alloy particles.

[0106] The kinetic current was calculated using the shown in Figure 4f, where a clear dominance of Pt3Co(i.3, t, -b) / fVC over all the other catalyst at all potential is visible. The mass activity of the final catalyst showed fivefold increment as compared to Pt / C , reaching 0.5 A mg'^t from 0.1 A mg-1pt at 0.85 V, and the specific activity also found to be higher for the same (Figure 4g, and 4h). The intrinsic activity final Pt3Co(i.3,t, -b) / fVC hot injected sample has been proven to have higher specific, mass and kinetic current activities compared to other counterparts. To further confirm the pathway of ORR, Koutecky- Levich (KL) analysis has been performed, it can be inferred from (Figure 4i) that the reaction on the surface of the PtsCopj, t,g-b) / fVC is following the 4 electron pathway, which has been correlated to the percentage of formation of peroxide 3% and 3.9 electron minimized through rotating ring disk electrode (RRDE) analysis. Overall, these studies clearly validate the fact that controlled particle size platinum centers enriched with electrons due to the transfer of electron form cobalt and induced twin (highly strained) and grain boundary defects in platinum (111) plane not only provide a better control over alloying but also improved performance with faster kinetics.

[0107] (9) Durability testing of the electrocatalyst:

[0108] The durability testing of the catalyst was performed in 0.1 M HCIO4 electrolyte in the kinetic region spanning from 0.6 to 1.0 V vs. RHE at a scan rate of 100 mVs1. Along with the leap in ORR capability of the catalyst, the alloying plays another significant role in enhancing its PT / 2025 / 13854 durability. The electronic interaction between cobalt and platinum along with the defects in the platinum plane, collectively contributed to enhance its durability. Thus, all the catalysts prepared through hot injection were expected to be stable and, indeed they all exhibited stability (Figure 5 - a, b, c, d, e and f). Interestingly, the slight deuteriation were visible in the case Pt3Co(2.7, t,g-b) / fVC-160 at the bottom of kinetic region 0.7 V vs. RHE with an improvement in onset region but maintaining the same E1 / 2. Assessing the stability of Pt Cou.x.t.g-b) / fVC-180, its performance improved after 20 thousand cycles in every aspect, including onset, E 1 / 2, and limiting current. Finally, the final catalyst PtsCopj, t,g-b) / fVC-200, exhibited not only superior performance compared to other counterparts but also high stability of all the samples after ADT. In contrast, state-of-the-art Pt / C (40%) showed degradation in performance after 5 thousand cycles, with decrease in E1 / 2 itself by 15 mV. Regarding the hot injected samples, it is well known that during accelerated durability test (ADT), there is a continuous and reversible formation and reduction of Pt-0 species on the surface. The tendency to form Pt-0 passivation layer is attributed to the oxyphilic nature of small platinum particles due to higher surface energy. Thus, as the samples hot injected at 180 and 200 °C have an average particle size of 1.8 nm and 1.3 nm, respectively, they are highly stable. Even after the increment in the performance for Pt3Co(i.8,t,g-b) / fVC-180, it was still found to be less effective than final catalyst at 200 °C.

[0109] Example 3: Comparing the present invention with commercially available electrocatalysts when used in HTPEMFC

[0110] Here, the doped PBI membrane with ortho phosphoric acid was used as the membrane. The catalyst was brush coated over 38 BC SGL GDL using 20 % Nafion and 60 % PTFE as binder. It was targeted to have an overall loading of 0.8 mg cm-2for PpCoi . t.g-b) / VC-200 and 1 mgcnT2for Pt / C. The brush-coated electrode was dried at 120° C for 4 hr then the two electrodes were used to sandwich the doped PBI membrane at 1 metric ton load for 10 minutes forming the membrane electrode assembly. This MEA was then placed in a fixture of 45 cm2with a torque of 3 Nm on both sides (Figure 6a).

[0111] Testing was performed in both H2-air and H2-O2 atmospheres. While few catalysts have been reported for HTPEMFCs, most work has been limited to smaller areas, typically 5 or 9 cm2. Here, inventors aimed to evaluate performance for an area more conducive to practical applications, specifically 45 cm2, operating at 160 °C. The loading of Pt / C(40%) catalyst was 1 mg cm-2, while Pt3Coi.3(t,g-b) / fVC-200 was significantly lower at 0.8 mgcm’2. Here the transfer PT / 2025 / 13854 of proton occurs through and phosphoric acid doped polybenzimidazole membrane from anode to cathode. The importance of HTPEMFC is well known for its high tolerance to impurities and better water and heat management. A comprehensive protocol for condition of membrane electrode assembly (MEA) was implemented prior to recording of the polarization curve. The performance of the catalyst was compared with the MEA fabricated of the state-of-the-art Pt / C (40%) under identical conditions. From the polarization curve in O2 atmosphere, it is clear that Pt3Coi.3(t,g-b) / fV C-200 achieved a current density of 1.18 Acm-2, while that of Pt / C based system was provided only 0.93 A cm'2. This translates to an actual current of 53 A for the catalyst and 42 A for Pt / C (Figure 6b). The overall power density for the catalyst has reached 1002 mWcm'2compared to the 960 mWcm'2surpassing all the reported value at this loading. Surpassing Pt / C JM by 11 A at a practical scale is indeed the breakthrough in this field. Moving to the more complicated aspect of this technology, the behavior of catalyst in the air atmosphere was tested. It is well known that performance drops significantly compared to oxygen. In air, the current density reached 0.44 Acm-2(19.8 A) for the Pt / C, while that of PtsCopj, t,g-b) / fVC-200 has shown 0.51 Acm-2(23 A) (Figure 6b), outperforming Pt / C by a considerable margin. To test the durability of the catalyst, it was run continuously for approximately 1600 minutes (approx. 27 h) in air at 22 A. Remarkably, it remained stable, showing only a 2mV drop. Thus, it is evident that Pt3Co(i.3,t,g-b) / fVC-200 stand far ahead in terms of performance, durability, and stability. The catalyst was stable even after 27 h (Figure 7). A detailed kinetic analysis was performed for the catalyst and standard were the kinetic current plot (Figure 6c) shows the catalyst is improved activity than Pt / C same was authenticated through tafel analysis (Figure 6d). Catalyst has shown the slope of 0.11602 and that of Pt / C 0.9137 mVdec1. Solid-state cyclic voltammetry was performed in H2 and N2 conditions to analyze the effective utilization of platinum. The ECSA was found to be 40 m2mg-1pt, and that of Pt / C was only 21 m2mg-1ptcomparing with the half cell value it can be understood that nearly 50% of platinum is utilized for Pt3Co(i.3, t,g-b) / fVC-200 and close to 30% for the Pt / C clearly stating the reason for the enhanced performance of the present catalyst (Figure 6e). Further, the comparison of the present catalyst over the reported ones, showing the improvement of the catalyst is provided in table 2 below:

[0112] Table 2: Comparison of HTPEMFC performance with reported catalyst in literature. PT / 2025 / 13854

[0113] Example 4: Comparing the present invention with Pt / C when used in LTPEMFC

[0114] Finally, the catalysts were tested for LTPEMFC (low temperature proton exchange membrane fuel cell) also in Hi-Air atmosphere. Here a decal-based coating method was implemented using bar coating for testing the catalyst. Pt / C has shown a current density of 1.37 AcnT2at 0.6 V vs RHE while the Pt3Co(i.3)(t,g-b)-200 has rendered 1.5 Acm'2. Surpassing Pt / C by 9.5 %

[0115] (Figure 6f). The kinetic studies performed both the system have shown the Pt3Co(i.3)(t,g-b)-200 is beating the Pt / C in both kinetic current and tafel slope aspect showing 0.11333 mVdec'1compared to 0.10904 for Pt / C (Figure 6 g and h). Finally, the solid-state CV analysis performed has given higher electrochemical active surface area that Pt / C (Figure 6i). ADVANTAGES OF THE INVENTION:

[0116] • Provides the electrocatalyst with lower cost of materials. PT / 2025 / 13854

[0117] • Electrocatalyst with higher stability and durability of Pt in alloy form with functionalized support, when compared with the state-of-the-art Pt / C catalyst.

[0118] • Electrocatalyst with better control over particle size of Pt.

[0119] • Avoids or lessens sluggish kinetics specifically onto Pt-111 plane, hence, better ORR performance thus increasing fuel cell performance and stability.

[0120] • Provides the electrocatalyst with better stability in an acidic environment.

[0121] • Electrocatalyst having 2D twin and grain boundary defects, which increases ORR by higher oxygen availability and also increases stability considering presence of metal (e.g. Co) which forms alloy with Pt. • Modulates the electronic environment of the platinum by shifting the electron density away from platinum both in XPS and d band center through valance band XPS.

Claims

PT / 2025 / 13854WE CLAIM:

1. An electrocatalyst for a proton exchange membrane fuel cell, comprising: a platinum-metal (Pt-M) alloy, on a support material wherein the Pt-M alloy is enriched with two-dimensional (2D) twin and grain boundary defects.

2. The electrocatalyst as claimed in claim 1, wherein the metal M is selected from the group consisting of cobalt, scandium, titanium, iron, nickel, zinc, yttrium, tin, magnesium, molybdenum, palladium, zirconium, iridium, ruthenium, and rhodium.

3. The electrocatalyst as claimed in claim 1, wherein the support material selected from the group consisting of vulcanized carbon, metal oxide, carbon black, and graphite.

4. The electrocatalyst as claimed in claim 1, wherein the metal (M) in said alloy of electrocatalyst is in the range of 8.3 to 10.3 mass %5. The electrocatalyst as claimed in claim 1, wherein the atomic percentage of platinum in the alloy is in the range of 72% to 82% and the atomic percentage of metal M is in the range of 20% to 28%.

6. The electrocatalyst as claimed in claim 1, wherein the particle size of the Pt-M alloy is in the range of 0.9 nm to 2.8 nm.

7. A process for preparing an electrocatalyst for a proton exchange membrane fuel cell, the process comprising: a) activating and functionalizing a support material selected from the group consisting of vulcanized carbon, metal oxide, carbon black, and graphite by treating the support with an oxidizing agent at a temperature in the range of 0°C to 5 °C under sonication to obtain a dispersion, followed by heating the dispersion at a temperature in the range of 50°C to 70°C under reflux conditions for a period of 7 to 9 hours to obtain an activated and functionalized support;PT / 2025 / 13854 b) preparing a support dispersion by adding the activated and functionalized support to a mixture of solvents under sonication for 7 to 10 hours, followed by refluxing at a temperature in the range of 160°C to 200°C for 3 to 8 hours to obtain mixture A; c) preparing an alloy dispersion by adding a platinum precursor and a metal precursor, wherein the metal is selected from the group consisting of cobalt, scandium, titanium, iron, nickel, zinc, yttrium, tin, magnesium, molybdenum, palladium, zirconium, iridium, ruthenium, and rhodium, to a mixture of solvents and heating at 70°C for 3 hours under sonication to obtain mixture B; d) heating mixture A to a temperature in the range of 160°C to 200°C in a reflux condenser setup, and injecting mixture B into mixture A, maintaining the reaction for 5 to 10 minutes to induce alloying and the formation of two-dimensional twin and grain boundary defects in the Pt-M alloy; e) filtering and drying the resulting crude electrocatalyst to obtain the electrocatalyst comprising a Pt-M alloy enriched with two-dimensional twin and grain boundary defects, wherein the particle size of the Pt-M alloy is in the range of 0.9 nm to 2.8 nm, and the electrocatalyst is substantially free of metallic impurities and oxide by-products.

8. The process of claim 7, wherein the platinum precursor and the metal precursor are selected from acetylacetonate, acetate, or nitrate salts.

9. The process of claim 7, wherein the atomic ratio of platinum to metal M in the alloy is approximately 3:1.

10. The process of claim 7, wherein the dried electrocatalyst is further dried under vacuum at a temperature in the range of 100°C to 120°C.

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