Ionomers composition, process of preparation and application in proton exchange membrane fuel cells

Abstract

The present invention relates to the in-situ generation of low molecular weight ionomers to enhance the triple-phase boundary in a 3D structured carbon-supported catalyst and the process for its preparation and application thereof.

Description

[0001] IONOMERS COMPOSITION, PROCESS OF PREPARATION AND APPLICATION

[0002] IN PROTON EXCHANGE MEMBRANE FUEL CELLS

[0003] FIELD OF THE INVENTION

[0004] The present invention relates to electrochemistry. The present invention is related to ionomer composition for proton exchange membrane fuel cell (PEMFC) for improved fuel cell efficiency. The present invention also relates to the process of preparing in situ generated, fluorine-free ionomer composition for optimizing the triple phase boundary for enhanced electrochemical surface area (ECSA). The invention further relates to preparing the half cell and the full cell PEMFC comprising the ionomer composition.

[0005] BACKGROUND OF THE INVENTION

[0006] Concern over environmental degradation and energy shortages have increased globally due to the depletion of finite fossil fuel supplies. As a result, efficient and sustainable renewable energy sources must replace traditional fossil fuels. With a substantially greater energy density (120 MJ kg-1) than gasoline (44 MJ kg-1), hydrogen is considered a leading candidate for the clean energy transition because of its eco-friendliness, sustainability, and abundant availability. Proton exchange membrane fuel cells (PEMFCs) are a fuel cell technology that is distinguished by its superior power density, lightweight design, and compact size. Given the pressing need to address climate change, hydrogen fuel cells (HFCs) are considered to be highly promising energy solutions that offer emission-free operation and exceptional efficiency. Hydrogen fuel cells (HFCs) are recognized for their significant role in forming a sustainable energy landscape by producing heat and electricity through electrochemical processes.

[0007] Proton exchange membrane fuel cells (PEMFCs) are efficient and clean electrochemical energy sources, but the high cost and limited availability of Pt catalysts have made PEMFCs difficult to commercialize. It has been demonstrated that the most promising nonprecious metal catalysts to replace Pt for usage in PEMFCs to catalyze the cathodic oxygen reduction reaction (ORR) are pyrolyzed transition metal / nitrogen / carbon (M / N / C) compounds, particularly Fe / N / C. The intrinsic activity of previously produced Fe / N / C catalysts, which has largely been evaluated in aqueous rotating disk electrodes (RDEs), has been considerably increased by active site structure probing and material invention, and in certain cases, it has even reached close to that of platinum. Nonetheless, there is a significant discrepancy between fuel cells and aqueous electrode experiments, which mostly stems from the notable variations in reaction interfaces. Though there has been considerable research in pyrolyzed transition metal / nitrogen / carbon (M / N / C) compounds, it is noted that the since ORR (oxygen reduction reaction) occurs at the solid-liquid two-phase interface in the aquatic RDE test which is in contrast to the triple-phase boundary (TPB), that is the point of contact between the electrocatalyst, electrolyte, and reactant gas, in fuel cells. Because of this, many ORR catalysts that exhibit strong performance in water RDE studies do not demonstrate great efficiency in fuel cells. Furthermore, perfluorosulfonic acid poly electrolytes, such as Nafion, are employed in PEMFCs to stop electrolyte leaching. Only H+can migrate because the sulfonic anion is bound on the polymer backbone, unlike free acids (such as H2SO4 or HCIO4) that are in aqueous experiments. The TPB is particularly complicated for heterogenetic Fe / N / C catalysts with atomically scattered active sites in porous materials due to the single-ion mobility and high molecular size of Nafion. Ionomers are ion-containing polymers where the ionic groups are covalently bonded to the polymers’ backbone. These ionic groups are neutralized by mobile ions of opposite charge (counter-ions), which gives an ionomer its ion-conductive properties, a critical functionality for transporting ions in solid-electrolyte membranes. Ionomers function as a proton-exchange membrane (PEM). A widely used ionomer for PEM, especially in fuel-cells, is perfluorosulfonic-acid (PFS A), due to its remarkable proton transport properties and chemicalmechanical stability. While the high proton conductivity of PFS A is attributed to its hydrophilic sulfonic-acid groups, and their hydration with water, the stability of this ionomer is imparted by its hydrophobic polytetrafluoroethylene (PTFE) backbone. However, due to some limitations of PFSA membranes, such as poor conductivity in anhydrous conditions, high manufacturing costs, and degradation of their properties at higher temperatures, there is a need for further research into polymer composite materials that maintain proton conductivity and fuel cell performance.

[0008] Nafion® is a well-known perfluorosulfonated polymer (PFSA), known for robust proton conductivity, mechanical resilience, and chemical resistance. They are used in the latter as solid electrolytes to transport cations selectively and as effective internal separators between the anode and cathode chambers. However, despite extensive research and refinement, Nafion® faces hurdles in widespread adoption due to many drawbacks. Including, its high synthesis cost due to intricate fluorine chemistry and its operational requirement of high humidity within a limited temperature range. The materials results in Pt underutilization after mixing with an ionomer like Nafion®, the prevalent process for triple phase boundary (TPB) formation. This limitation arises as the TPB is not expected to extend to the inner cavities and micro-regions of the carbon support where Pt particles may reside. Nafion is also said to result in the formation of hydrofluoric acid (HF), which induces the leaching of platinum (Pt) nanoparticles from the catalyst support. Consequently, a reduced number of Pt active sites are available for the reaction, and these sites may be progressively leached out along with Nafion over extended operational periods. This process ultimately decreases the overall durability of the system. Therefore, replacing high molecular weight Nafion® could allow for the utilization of Pt particles located in these internal regions.

[0009] As per, “ Development of ionomer membranes for fuel cells'', Journal of Membrane Science 185 (2001) 3-27, the advantage of the covalently cross-linked ionomer membranes was their dimensional stability even at temperatures of 80-90 °C, while their main disadvantage was their brittleness when drying out, caused by the inflexible covalent network. Such polybenzimidazole (PBiytUPCU membranes are advantageous due to their flexibility even when dried-out, good to excellent thermal stability, and the numerous possibilities to combine acidic and basic polymers to blend membranes having fine-tuned properties. They are also particularly advantageous compared onto Nafion®, in as much that they are much cheaper than Nafion®. Their main disadvantage is that the H3PO4 molecules can diffuse out of the membrane because they are in excess towards basic polymer sites (six H3PO4 molecules per PBI repeating unit).

[0010] In a proton-exchange membrane (PEM), phosphoric acid is used as the primary protonconducting electrolyte particularly in high-temperature proton exchange membrane (HT-PEM) fuel cells because it provides high proton conductivity at high temperatures (100-200 °C), unlike conventional PEMs. The phosphoric acid is doped into an alkaline polymer membrane, such as polybenzimidazole (PBI), forming a composite membrane that operates without the need for liquid water for proton conduction. However, a significant challenge is the loss of phosphoric acid from the membrane-electrode assembly (MEA) due to water condensation or electro-migration which can lead to performance deterioration. Phosphoric acid anions adsorb onto the platinum catalyst surface, impairing the oxygen reduction reaction kinetics and reducing overall fuel cell performance. Hence there is a need for better water uptake mechanisms that can prevent the loss of phosphoric acid.

[0011] Due to considerable challenges in replacing Pt catalysts, researchers working on improving the performance of platinum electrocatalysts and their utilization efficiency in Proton exchange membrane fuel cells (PEMFCs) have developed an electrocatalyst (Pt / 3DNG) for PEMFC applications by using nitrogen-doped 3D graphene (3DNG) as the support material and an in situ grafted active “triple-phase boundary” to more precisely control the formation of the proton conducting ionomer interface at the active sites as disclosed in “ / n Situ Preparation of Ionomer as a Tool for Triple-Phase Boundary Enhancement in 3D Graphene Supported Pt Catalyst” Gangadharan et.al, July 2020, Advanced Sustainable Systems.

[0012] However, there is still an urgent need to overcome the problems in prior art which include performance deterioration of the fuel cell due to electrolyte leaching, poor proton conductivity in anhydrous conditions, loss of phosphoric acid, low reactivity at the triple-phase boundary (TPB) of the PEMFC coupled with the requirement to enhance catalyst activity which would enabling reduction in the amount of the state-of-the-art Pt catalyst loading for cost-effective PEMFC assemblies for practical applications. Considering the drawbacks mentioned, there is a need to develop better-performing PEMFCs to address the issue.

[0013] OBJECTS OF THE INVENTION

[0014] It is an object of the present invention to provide an ionomer composition for proton exchange membrane fuel cells (PEMFC).

[0015] It is another object of the present invention to provide for the enhancement of the triple phase boundary (TPB) in proton exchange membrane fuel cells (PEMFC).

[0016] It is yet another object of the present invention to improve the electrode performance of PEMFCs by enhancing Pt electrode utilization.

[0017] It is another object of the present invention to provide for a process for preparing an ionomer composition for proton exchange membrane fuel cells (PEMFC).

[0018] It is another object of the present invention to provide for a process for preparing an electrode with the ionomer composition.

[0019] It is another object of the present invention to provide for the in-situ polymerization of monomer to facilitate TPB formation.

[0020] It is yet another object of the present invention to provide for a half-cell and full-cell PEMFCs with said ionomers composition.

[0021] SUMMARY OF THE INVENTION

[0022] The present invention provides for an ionomer composition for Proton exchange membrane fuel cells (PEMFC) comprising: a. at least one monomer; b. a cross linking agent; c. a weak acid; d. a binding agent; and e. a UV initiator. wherein the monomer is a short chain low molecular weight monomer. In an embodiment the present invention provides an ionomer composition where the monomer is in the range of 10-20 wt%, cross linking agent is in the range of 15-20 wt%, weak acid is in the range of 10-50 wt%, binding agent is in the range of 30-35 wt% and UV initiator is in the range of l-2wt% of the total weight of the composition.

[0023] In an embodiment, the ionomer composition of the present invention comprises the monomer, cross-linking agent, and binding agent in a ratio in the range of 0.5:0.05:0.5 to 1:2:2.

[0024] In an embodiment, the ionomer composition of the present invention comprises a monomer hydroxypropyl methacrylate (HPMA), a cross-linking agent trimethylolpropane diallyl ether (TMDAE), phosphoric acid, a phosphoric acid binding agent 2-(trimethylammonio) ethyl methacrylate chloride (TMAEM) and a UV Initiator 2-hydroxy-2-methylpropiophenone (HMPP).

[0025] In an aspect, the present invention provides for a process of preparing an ionomer composition comprising the steps of: a. mixing a low molecular weight monomer, crosslinking agent and phosphoric acid binding agent in a suitable ratio; b. stirring the mixture of step (a) after adding a weak acid in the presence of a UV initiator; and c. irradiating the solution of step (b) with UV radiation to obtain an ionomer composition. In another aspect, the present invention provides a process for preparing an electrode with the ionomer composition.

[0026] In an aspect, the present invention provides a process for preparing an electrode comprising the steps of: i. preparing a solution of a transition metal catalyst in a suitable solvent; ii. adding an ionomer composition comprising at least one monomer; a cross-linking agent, a weak acid, a binding agent and a UV initiator wherein the monomer is a short chain low molecular weight monomer to the solution of step (i); iii. sonicating the mixture of step (ii) and coating the mixture uniformly over a Gas Diffusion Layer or coating the mixture of step (ii) on the electrode with the Gas Diffusion Layer; iv. irradiating the coating of step (iii) with UV radiation for in-situ generation of ionomers and obtaining the electrode.

[0027] It another aspect, the present invention provides for a half-cell and full-cell PEMFC comprising an ionomer composition comprising at least one monomer, a cross linking agent, phosphoric acid, a phosphoric acid binding agent and a UV initiator wherein the monomer is a short chain low molecular weight monomer.

[0028] In an embodiment, the present invention discloses a half proton-exchanging membrane fuel cells consisting of said composition of ionomers, wherein said half-cell comprises of:

[0029] - working electrode coated with a composition of in situ generating ionomers for triple phase boundary;

[0030] - reference electrode;

[0031] - counter electrode; and

[0032] - electrolyte.

[0033] In an embodiment, the present invention discloses full proton-exchanging membrane fuel cells comprising an ionomer composition, wherein said full-cell comprises of:

[0034] - an anode coated with a composition of in situ generating ionomers for triple phase boundary;

[0035] - a cathode coated with a composition of in situ generating ionomers for triple phase boundary;

[0036] - 3D structured supported catalyst; and

[0037] - a gas diffusion layer coated with a composition of in situ generating ionomers for triple phase boundary.

[0038] BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

[0039] Figure 1: The FT-IR, spectra of HTAP precursor solution and HTAP ionomer.

[0040] Figure 2: The Ion exchange capacities (lECs) and water uptakes (WU) of HTAP thin films at 80 °C.

[0041] Figure 3: The bar diagram depicting proton conductivity values of HTAP- 112 at different temperatures.

[0042] Figure 4: The Arrhenius plot of HTAP at different temperatures to calculate activation energy. Figure 5: 5a and 5b: FESEM images of HTAP- 112 thin film depicting the porous nature.

[0043] Figure 6: FESEM images of 6a, b) conventional Nafion® ionomer-based electrode, 6c, 6d) HTAP- 112 based electrode, FESEM cross sectional images of 6e) Nafion® based electrode, 6f) HTAP- 112 ionomer-based electrode, 6g) F mapping of the Fig. 6e and 6h) Cl mapping of the Fig. 6f.

[0044] Figure 7: The BET isotherms of dried catalyst slurry made with HTAP- 112, Nafion ionomer and without ionomers. Figure 8: The pore size distribution profiles (magnified profile in the inset for better understanding) of dried catalyst slurry made with HTAP-112, Nafion ionomer and without ionomers.

[0045] Figure 9: HRTEM images Pt / C catalyst with a) Nafion® ionomer, and b) with HTAP-112 ionomer.

[0046] Figure 10: a) The comparative CV profiles corresponding to ORR in 0.1 M HCIO4 of Pt / C with Nafion® and HTAP-112 ionomers, b) plot of ECSA vs. VC ratios.

[0047] Figure 11: The comparative CV profiles with varying VC ratios of a) Nafion® and b) HTAP- 112 ionomers.

[0048] Figure 12: The representative scheme of preparation of the in-situ ionomer-based electrode fabrication.

[0049] Figure 13: The comparative I-V polarization plots recorded during the single-cell evaluation Pt / C based MEA with HTAP-112 and Nafion-PTFE ionomer in a) H2-O2, b) H2-Air feed conditions, c) Stability test of the MEA based on HTAP-112 ionomer at constant current, d) comparative I-V polarization plot before and after the stability test.

[0050] Figure 14: The comparative I-V polarization plots recorded during the single-cell evaluation PV3DPDC based MEA with HTAP-112 ionomer in e) H2-O2, f) H2-Air feed conditions.

[0051] Figure 15: The stability test of the MEA based on the HTAP-112 ionomer at constant current for about 100 h of duration.

[0052] DETAILED DESCRIPTION OF THE INVENTION

[0053] The present invention relates to an ionomer composition for Proton exchange membrane fuel cells (PEMFC) comprising: a. at least one monomer in a range of 10-20 wt%; b. a cross linking agent in a range of 15-20 wt%; c. a weak acid in a range of 10-50 wt%; d. a phosphoric acid binding agent in the range of 30-35 wt%; and e. a UV initiator in the range of l-2wt% of the total weight of the composition, wherein the monomer is a short chain low molecular weight monomer.

[0054] In the PEMFCs, the electrochemical reactions (hydrogen and methanol oxidation reaction at anode and oxygen reduction reaction (ORR) at cathode) mainly occurs at the triple phase boundary (TPB) zones, where the catalytic particles, electrolyte phase, and gases pores intersect. These redox reactions necessitate fuel transport in the electrode porous area, ionic transport in the electrolyte, and charge transport in the electrodes. TPB’s therefore strongly influence the activity and durability of the PEMFC electrodes. Conventionally, the PEMFC electrodes were prepared by mixing the Pt / C catalyst and ionomer; then the homogeneous slurry was loaded onto the surface of the gas diffusion layer (GDL) by conventional methods, including spray and decal, etc. However, these methods could not situate all of the Pt catalyst nanoparticles at the front of the membrane. This greatly reduced the Pt catalytic utilization since the generated protons on the Pt catalyst immediately pass across the membrane without any extinction. The conventional methods also significantly decreased the amount of the triple phase boundary (TPB) because the Pt catalysts often localized in the thick conventional layer and a part of the Pt catalysts supported on carbon were not contacted with the ionomer, thus making them inactive and inaccessible to the fuels.

[0055] The ionomer composition of the present invention which is in situ-generated and fluorine-free, comprises of low molecular weight monomers that grow within the micro-regions and inner cavities of a catalyst support, where the underutilized Pt catalyst active sites reside. The precursor monomers infiltrate these regions and then polymerize to form ionomer networks within the inner regions, thereby optimizing the triple phase boundary for enhanced electrochemical surface area (ECSA) leading to the enhanced efficiency of the PEMFC. The ionomer composition of the present invention enables the efficient deposition of catalysts on the electrodes for the enrichment of the TPBs thereby maximizing catalytic utilization.

[0056] The present invention further relates to the enhancement of electrode performance of PEMFC s by enhancing Pt utilization in the state-of-the-art catalyst. The ionomer composition of the present invention surprisingly enables to engineer the micro structure of the catalyst support to create extended active triple-phase boundary (TPB). While Pt is crucial for reaction sites, Pt support structures also provide essential electronic support to Pt nanoparticles. Ensuring appropriate TPB maintenance for Pt nanoparticles anchored over the carbon support is vital for facilitating the interface between the Pt surface, ionomer composition, and reacting gases. The microstructures of the ionomer-catalyst interfaces in the catalyst layers as enabled by the ionomer composition of the present invention, significantly influence fuel cell performance by determining active TPB distribution. The ionomer composition of the present invention reverses the underutilization of the Pt catalyst leading to an increase in mass activity by integrating an in situ generated ionomer interface derived from pre-admitted low molecular weight monomers into the system. As high temperature-PEMFCs require immobilized H3PO4, ideally in a uniformly distributed polymer matrix around active Pt particles, the present invention further discloses an in situ polymerization of monomers with H3PO4 moieties facilitating the TPB formation in the inner regions of the electrode. In an embodiment, the present invention provides an ionomer composition, wherein the low molecular weight monomer is in the range of 10-20 wt%, cross linking agent is in the range of 15-20 wt%, weak acid is in the range of 10-50 wt%, binding agent is in the range of 30-35 wt% and the UV Initiator is in the range of 1-2% wt%.

[0057] In a specific embodiment of the ionomer composition, the low molecular weight monomer is 17 wt%, cross linking agent is 17 wt%, weak acid is 30 wt%, binding agent is 34 wt% and the UV Initiator is 2 wt% of the total weight of the composition.

[0058] In another specific embodiment of the ionomer composition, the low molecular weight monomer is 14.55 wt%, cross linking agent is 13.28 wt%, weak acid is 34.69 wt%, binding agent is 31.08 wt% and the UV Initiator is 0.27 wt% of the total weight of the composition.

[0059] In the catalyst layer of the present invention, the molecular weight (MW) of the ionomer (a polymer that conducts protons) influences the electrode's microstructure. It has been observed that low molecular weight monomers that are typically less than 1000 Da are able to grow within the micro-regions and inner cavities of the catalyst support, where underutilized Pt active sites reside. The precursor monomers infiltrate these regions and polymerize to form ionomer networks within the inner regions. This is enabled by the flexibility and hydrophobicity of the low molecular weight monomers.

[0060] Thus, the low molecular weight monomers as comprised in the present invention leads to increased free volume, which enhances mass transport and catalyst utilization thereby optimizing the triple phase boundary for enhanced electrochemical surface area (ECSA). In an embodiment the lower molecular weight monomer facilitates the polymerization of monomers within the nanopores of the carbon support.

[0061] In an embodiment, the low molecular weight polymer is selected from but not limited to Hydroxypropyl methacrylate (HPMA), 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2 -hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate. In a specific embodiment the low molecular weight monomer is hydroxypropyl methacrylate (HPMA). In a specific embodiment, the lower molecular weight monomer is hydroxypropyl methacrylate (HPMA).

[0062] The present invention relates to ionomer composition comprising low molecular weight monomers in the range of 10-20 wt% of the total composition. Preferably the low molecular weight monomer is 14.55 wt% of the total ionomer composition. Preferably the monomer is 17 wt% of the total ionomer composition.

[0063] The crosslinking agent present in the ionomer composition of the present invention helps create a stable, three-dimensional polymer network within the proton exchange membrane (PEM), enhancing mechanical strength, thermal stability, and reducing excessive water uptake and fuel crossover. They form a rigid, interconnected structure, preventing the polymer chains from sliding past each other, which is crucial for the long-term integrity of the PEM. The crosslinking agent of the present invention particularly maintains and improves proton conductivity. In an embodiment, the cross-linking agent is selected from but not limited to Trimethylolpropane diallyl ether (TMDAE), N'-methylenebisacrylamide, Trimethylolpropane allyl ether 2-((allyloxy)methyl)-2-ethylbutan-l-ol, ethylene glycol dimethacrylate, poly (ethylene glycol) diacrylates, epichlorohydrin, and glutaraldehyde. Preferably, the crosslinking agent is Trimethylolpropane diallyl ether (TMDAE).

[0064] The cross linking agent in the ionomer composition of the present invention is generally in a range of 15-20 wt% of the total composition. Preferably the cross linking agent is 17 wt% of the total ionomer composition. More preferably, the cross-linking agent is 13.28 wt% of the total ionomer composition.

[0065] The weak acid present in the ionomer composition of the present invention is an electrolyte utilized in a high-temperature Proton Exchange Membrane Fuel Cell (HT-PEMFC), for acting as a proton conductor at operating temperatures of 130-220 °C having significant stability and broad fuel flexibility. The weak acid is selected from but not limited to phosphoric acid, formic acid, acetic acid or hydrofluoric acid. The weak acid is generally present in the range of 10 - 50 wt% of the total composition. Preferably the weak acid is 30 wt% of the total ionomer composition. More preferably, the weak acid is 34.69 wt% of the total ionomer composition. In an embodiment, the weak acid is phosphoric acid.

[0066] The binding agent contained in the ionomer composition typically maintain the porous structure of the catalyst layer by holding the platinum catalyst particles and carbon support together forming interconnected pathways. Binding agents are critical components, especially in PEMFCs, that provide structural integrity to the catalyst layer while simultaneously facilitating ion and gas transport. The binding agent of the present invention particularly facilitates enhanced weak acid uptake, as the weak acid serves as the electrolyte in proton exchange membrane fuel cells (PEMFCs). In an embodiment, the binding agent is selected from but not limited to 2-(Trimethylammonio) ethyl methacrylate chloride (TMAEM) and (Acryloyloxy) ethyl] trimethylammonium chloride. Preferably, the binding agent is 2 - (Trimethylammonio) ethyl methacrylate chloride (TMAEM).

[0067] Photo initiators / UV initiators facilitate the rapid and efficient curing of polymer electrolytes under UV light, enabling the creation of specialized inorganic-organic hybrid membranes with high proton conductivity and durability for fuel cell operation. In an embodiment, the UV initiator is selected from but not limited to 2-hydroxy-2-methylpropiophenone (HMPP), Hydroxycyclohexyl phenyl ketone (Irgacure 184), 2-Benzyl-2-(dimethylamino)-4'- morpholinobutyrophenone (Irgacure 369), 2,4,6-Trimethylbenzoyldiphenylphosphine oxide (TPO), Benzoin methyl ether (BME), 2-Methyl-l-[4-(methylthio)phenyl]-2- morpholinopropan-l-one(Irgacure907) and Benzoin isobutyl ether (BIBE). Preferably, the UV initiator is 2-hydroxy-2-methylpropiophenone (HMPP).

[0068] In an embodiment of the present invention, the low molecular weight monomer, cross-linking agent, and phosphoric acid binding agent, in a volume ratio in the range of 0.5:0.05:0.5 to 1:2:2. Preferably, the ratio is 1: 1: 1 or 1: 1:2 or 1:2: 1. The presence of phosphoric acid binding agent in the said ratio enhances the ion exchange capacity of the ionomer composition. In an embodiment, present invention relates to the ratios of HPMA: TMPDAE: TMAEM in the ionomer composition, wherein the ratios selected from 1: 1: 1, 1: 1:2, and 1:2: 1, are denoted as HEAP- 111, HEAP- 112, and HEAP- 121 , respectively.

[0069] In another embodiment of the ionomer composition, the monomer hydroxypropyl methacrylate (HPMA) is 14.55 wt%; cross linking agent trimethylolpropane diallyl ether (TMDAE) is 13.28 wt%; phosphoric acid is 40.81 wt%; binding agent 2-(trimethylammonio) ethyl methacrylate chloride (TMAEM) is 31.08 wt% and the UV Initiator 2-hydroxy-2-methylpropiophenone (HMPP) is 0.27 wt% of the total weight of the composition.

[0070] In another aspect, the present invention relates to a process for the preparing an ionomer composition for proton exchange membrane fuel cell (PEMFC) comprising the steps of: a. mixing a low molecular weight monomer, crosslinking agent and phosphoric acid binding agent in a suitable ratio; b. stirring the mixture of step (a) after adding a weak acid in the presence of a UV initiator; and c. irradiating the solution of step (b) with UV radiation to obtain an ionomer composition. In an embodiment, the ionomers are generated in situ.

[0071] In another embodiment, the weak acids are selected from but not limited to phosphoric acid (H3PO4), and acetic acid (CH3COOH), formic acid (HCOOH) and hydrofluoric acid (HF). In a specific embodiment, the weak acid is in the range of 10-50% v / v.

[0072] In an embodiment the process of preparing the ionomer composition comprises mixing hydroxypropyl methacrylate (HPMA) as the monomer; trimethylolpropane diallyl ether (TMDAE) as the cross linking agent; 2-(trimethylammonio) ethyl methacrylate chloride (TMAEM) as the binding agent and 2-hydroxy-2-methylpropiophenone (HMPP) as the UV Initiator. In another embodiment the ratio of monomer, cross -linking agent, and binding agent is in the range of 0.5:0.05:0.5 to 1:2:2. In another aspect, the present invention relates to a process for the in -situ preparation of the electrode using the said ionomer composition in PEMFCs comprises steps: i. preparing a solution of a transition metal catalyst in a suitable solvent; ii. adding an ionomer composition comprising at least one monomer; a cross-linking agent, weak acid, a binding agent and a UV initiator wherein the monomer is a short chain low molecular weight monomer to the solution of step (i); iii. sonicating the mixture of step (ii) and coating the mixture uniformly over a Gas Diffusion Layer or coating the mixture of step (ii) on the electrode with the Gas Diffusion Layer; iv. irradiating the coating of step (iii) with UV radiation for in-situ generation of ionomers and obtaining the electrode.

[0073] In an embodiment the catalyst may be selected from noble and / or non-noble transition metals decorated over carbon, silica and carbon derived from zeolites, and metal organic frameworks. In a specific embodiment, the sonication is carried out for 20-40 min. In a specific embodiment, the UV radiation is carried out for 20-40 min. In an embodiment, the solvent is selected from but not limited to alcoholic solvents such as methanol, isopropanol, ethanol, and propanol. In an embodiment, a mixture of water and solvent is utilized for preparing a solution of a transition metal catalyst in step i. Preferably the water and solvent are in a ratio of 3: 1.

[0074] In a specific embodiment, the present invention more particularly discloses the composition of in-situ generation of ionomers for the enrichment of the triple phase boundary in the 3D structured carbon-supported catalyst.

[0075] In an aspect, the present invention relates to a half-proton-exchanging membrane fuel cell comprising of an ionomer composition, wherein said half-cell comprises of:

[0076] - working electrode coated with a composition of in situ generating ionomers for triple phase boundary;

[0077] - reference electrode;

[0078] - counter electrode; and

[0079] - electrolyte.

[0080] In an embodiment, the reference electrode may be selected from platinum, standard hydrogen electrode, saturated calomel electrode, Silver / Silver Chloride electrode (Ag / AgCl), Mercury / Mercurous Sulfate Electrode (Hg / Hg2SO4), Copper / Copper Sulfate Electrode (Cu / CuSO4), and Lithium / Lithium Chloride Electrode (Li / LiCl). In yet another aspect, the present invention relates to a full proton-exchanging membrane fuel cells comprising of an ionomer composition, wherein said full-cell comprises of:

[0081] - an anode coated with a composition of in situ generating ionomers for triple phase boundary;

[0082] - a cathode coated with a composition of in situ generating ionomers for triple phase boundary;

[0083] - 3D structured supported catalyst; and

[0084] - gas diffusion layer coated with a composition of in situ generating ionomers for triple phase boundary.

[0085] In an embodiment, the 3D structured support catalyst may be selected from metal oxides (AI2O3, SiCh, TiCh), zeolites, carbon and carbon derived via the high temperature annealing of metal organic frameworks. Preferably, the support catalyst selected is a 3D structured carbon support catalyst.

[0086] The present invention further relates to thin ionomer films comprising: at least one monomer in the range of 10-20 wt%; a. a cross linking agent in the range of 15-20 wt%; b. a weak acid in the range of 10-50 wt%; c. a binding agent in the range of 30-35 wt%; and d. a UV initiator in the range of l-2wt % of the total weight of the composition; wherein the monomer is a short chain low molecular weight monomer.

[0087] The thin film ionomer composition maintains the catalyst's porosity and morphology without covering it up. The ionomer comprising low molecular weight monomers are able to penetrate into the nanopores and polymerize inside the nanopores of the catalyst support and hence are uniformly distributed throughout the electrode surface area. This ensures a porous structure which can be attributed to the increased cross-linking of the polymer chains of the low molecular weight monomers. Thus, the resultant higher electrochemically active surface area observed with the inventive ionomer-based electrode provides for enhanced exposure of Pt active sites within the inner cavities and micro-regions of the catalyst layer to reactive gases facilitating acid intake and high proton conductivity across the PEMFC.

[0088] The ionomer-to-carbon (I / C) ratio influences Electrochemical Surface Area (ECSA) by affecting proton conductivity and the availability of platinum (Pt) for reactions. A lower VC ratio can decrease proton conduction and cell performance, while an excessive VC ratio can block pores, hinder gas diffusion, and lead to increased degradation and reduced ECSA. The ionomer composition of the present invention remains effective even in low VC for effective PT / C catalysis. The ionomer composition of the present invention provides for high electrochemical surface area (ECS A) values in a electrode given the exposure of Pt active sites that is possible within the inner cavities and micro-regions of the catalyst layer to reactive gases due to the inventive ionomer composition. An optimal VC ratio, which varies depending on the catalyst and application, is necessary to balance these effects and achieve high ECSA and overall fuel cell performance. The membrane electrode assembly (MEA) based on the ionomer composition of the present invention reflects significantly high current densities thereby increasing the efficiency of the PEMFC.

[0089] EXAMPLES

[0090] Following examples are given by way of illustration therefore should not be construed to limit the scope of the invention.

[0091] Example 1: Preparation of HTAP ionomer thin film for ex-situ analysis

[0092] The HTAP ionomer thin films were prepared by mixing monomer and the cross-linking agent and the phosphoric acid binding agent with a UV initiator and H3PO4, followed by UV irradiation in a plastic mold. In the procedure, 2-hydroxypropyl methacrylate (HPMA), trimethylolpropane diallyl ether (TMPDAE), and 2-(trimethylammonio) ethyl methacrylate chloride (TMAEM) were mixed at volume ratios (1: 1: 1, 1:2: 1, and 1: 1:2) respectively in 3 different set ups, along with 480 pl of H3PO4 (30% v / v) in the presence of 5 pl of 2-hydroxy- 2-methylpropiophenone (HMPP) UV initiator. Each of the solutions were appropriately subjected to vortex stirring for an hour. Then, the precursor solutions were transferred into a flat plastic mold and underwent UV irradiation for about 30 min.

[0093] Example 2: Ex-situ thin film characterization

[0094] TMPDAE, trimethylolpropane diallyl ether, employed to copolymerize with monomer HPMA was aimed at adjusting the hydrophobicity of the HTAP network structure. Additionally, TMPDAE which served as a cross-linking agent during polymerization, also contributed to the flexibility and smoothness of the ionomer thin film, which can be attributed to the plasticizing effect of TMPDAE. Given the low molecular weight of HPMA, it facilitated the polymerization of monomers within the nanopores of the carbon support. Furthermore, the polyelectrolyte properties of TMAEM (phosphoric acid binding agent) facilitated enhanced phosphoric acid uptake.

[0095] The comparative infrared (IR) spectra, as depicted in Figure 1, confirms the polymerization under the UV irradiation conditions. The peak corresponding to the C=C vibration at 1600- 1650 cm-1decreases in intensity in the sample after polymerization. Thin films of HTAP ionomers with three different (1:1: 1, 1:2: 1, and 1: 1:2) ratios were synthesized and their various properties were studied and compared with those of the commercially available Nafion-HP® membrane. The monomer ratios of HPMA: TMPDAE: TMAEM were 1: 1: 1, 1: 1:2, and 1:2: 1, denoted as HTAP-111, HTAP-112, and HTAP-121, respectively.

[0096] The ion exchange capacity (IEC) of all three ionomer thin films was evaluated using the titration method with Equation 1. As shown in Figure 2, HTAP-111, HTAP-112, and HTAP- 121 exhibited IEC values of 0.984, 1.5, and 1.1 meq. g-1, respectively. In contrast, the IEC for Nafion-HP® was 0.95 meq. g’1.

[0097] Water uptake (WU) was also studied for all three ionomer thin films (Figure 2). HTAP-112 demonstrated a highest water uptake of 61%, while that of HTAP-111 was 36% and HTAP- 121 was 44%. In contrast the water uptake of commercial Nafion-HP® was the lowest as it was found to be only 33%.

[0098] The reduced water uptake(WU) and ion exchange capacity (IEC) observed in Nafion-HP® can be attributed to the unique structural characteristics inherent in Nafion®. The higher IEC and WU of HTAP-112 and also that of HTAP- 111 and HTAP -121 can be attributed to the inclusion of TMAEM, which possesses a polyelectrolyte nature and also contains quaternary ammonium groups.

[0099] The proton conductivity of the HTAP-112 ionomer thin film was evaluated within the temperature range of 40-120 °C, maintaining a constant relative humidity (RH) of 95%. Proton conductivity exhibited an increasing trend with rising temperature under constant RH conditions (Figure 3). At 120 °C and 95% RH, the proton conductivity of HTAP-112 was measured to be 9.1 mS cm1. These values remain significantly high and hold promise for fuel cell development.

[0100] The activation energy of inventive example HTAP- 112 was determined by using temperaturedependent conductivity analysis. The activation energy was calculated by using the Arrhenius equation and found to be 0.53 eV, the corresponding Arrhenius plot is given in Figure 4. The obtained activation energy of 0.53 eV is relatively low, indicating that the ionomer facilitates efficient proton transport with minimal energy barrier. This suggests that the inventive composition exhibits superior proton conduction properties compared to conventional systems, thereby enhancing its suitability for fuel cell applications.

[0101] The morphology of the inventive example HTAP-112 ionomer thin film was examined using FESEM, as illustrated in Figure 5a and 5b, revealing a highly porous structure attributed to the increased cross-linking of the polymer chains, facilitating acid intake. Example 3: Preparation of electrode for in situ analysis

[0102] Catalyst ink was prepared by mixing 5.0 mg of the Pt / C or Pt / 3DPDC catalyst in a 1.0 ml solution of water and isopropanol in a ratio of 3:2, with a certain amount of ionomer precursor solutions added to achieve different lonomer / Carbon (PC) ratios (0.16, 0.33, and 0.66). The PC ratio refers to the ratio of ionomers to carbon. The ionomer here is the HTAP-based ionomer developed in this project. The carbon refers to the 3DPDC support, on which Pt nanoparticles are deposited. The mixture was sonicated for 30 min, after which it was coated onto a gas diffusion layer (GDL) to achieve a Pt loading of 0.02 mg. Following drying, the electrode underwent UV irradiation for 30 min.

[0103] Example 4: In situ electrode characterization

[0104] The morphology of this electrode was investigated using FESEM and compared to a conventional electrode fabricated with Nafion ionomer. Figures 6a and 6b suggest that the Nafion-based electrode completely covers up the catalyst's porosity and morphology, whereas the electrode fabricated via UV irradiation with the inventive HTAP-112 ionomer, maintains the catalyst's porosity, indicating that the low molecular weight HTAP-112 ionomer penetrates into the nanopores of the catalyst (Figure 6c and 6d). Cross-sectional images of electrodes are provided in Figure 6e indicate that the Nafion-based conventional electrode exhibits thick polymer coverage, obstructing the pores of the catalyst layer, whereas the HTAP-112-based UV polymerized electrode preserves the porous nature of the catalyst layer (Figure 6f). Cross- sectional EDAX elemental mapping in Figure 6h clearly indicates that chlorine, present in HTAP-112, is uniformly distributed throughout, suggesting that the low molecular weight ionomer has reached the nanopores of the carbon support. Conversely, fluorine, characteristic of Nafion® ionomer, is not uniformly distributed (Figure 6g).

[0105] The catalyst porosity-maintaining ability of HTAP-112 ionomer is further confirmed through Brunauer- Emmett-Teller (BET) surface area and pore size distribution analysis. The BET N2 adsorption-desorption isotherm is presented in Figure 7. The BET surface area of the binder- free Pt / C catalyst ink is measured at 160.27 m2g-1, which is reduced to 91.13 m2g-1for the catalyst ink containing the inventive HTAP-112 ionomer. Conversely, for the catalyst ink incorporating conventional Nafion® ionomer, the surface area is drastically reduced to 23.48m2 g -1 •

[0106] Furthermore, the pore size distribution profile in Figure 8 indicates that the porosity of the binder-free catalyst ink is diminished upon the addition of binders. The catalyst ink with Nafion® binder exhibits a pore volume of 0.118 cm3g1, significantly lower compared to the HTAP-112-based binder-free catalyst ink, which has a pore volume of 0.253 cm3g1, and the binder-free catalyst ink, with a pore volume of 0.374 cm3g1. The BET analysis further confirms that the inventive HTAP-112 ionomer-based catalyst layer preserves porosity and surface area by polymerizing inside the nanopores of the catalyst carbon support. This is in contrast to the conventional Nafion® ionomer-based catalyst layer, where Nafion® completely covers and blocks the nanopores of the carbon support of the catalyst.

[0107] The HRTEM images of the catalyst inks are analyzed to elucidate the ionomer distribution. As depicted in Figure 9a, the HRTEM image reveals that the Nafion® ionomer is not uniformly covering the Pt nanoparticles, exhibiting varying thicknesses exceeding 10 nm in certain regions. Conversely, in the case of the HTAP-112 ionomer-based catalyst ink, a uniform distribution throughout the catalyst is observed Figure 9b.

[0108] The higher viscosity of Nafion® makes achieving a uniform coating over the carbon morphology challenging. The enhanced interaction between the HTAP-112 ionomer and the state-of-the-art Pt / C catalyst is further confirmed through Zeta potential measurements. The Pt / C catalyst and Nafion® ionomer exhibit negative zeta potentials of -27 mV and -30.4 mV, respectively. In contrast, the HTAP-112 ionomer demonstrates a positive zeta potential of 20.3 mV. Polymers with a positive zeta potential and Pt / C materials carrying a negative charge are inclined to mutual electrostatic attraction owing to the presence of opposite electrical charges. This positive electrostatic interaction between HTAP-112 and Pt / C facilitates stronger ionomer-catalyst binding, leading to improved catalyst layer uniformity, enhanced proton conduction pathways, and better catalyst utilization, which collectively contribute to superior fuel cell performance

[0109] Example 5: Electrochemical characterization of the half-cell PEMFCs

[0110] The state-of-the-art Pt / C catalyst electrode, prepared with Nafion® and HTAP-112 ionomer, underwent electrochemical analysis in an N -saturated 0.1 M HCIO4 electrolyte within a 3- electrode system. The working electrode comprised a catalyst-coated gas diffusion layer (GDL), with Ag / AgCl serving as the reference electrode and a graphite rod as the counter electrode. Cyclic voltammetry (CV) was performed within the voltage range of 0 to 1.3 V vs. RHE. As illustrated in Figure 10a, the CV profile exhibited typical Pt characteristics, delineating regions associated with hydrogen and oxygen adsorption-desorption, as well as non-faradaic capacitance.

[0111] This yielded ECSA values of approximately 36.01 m2g1for the electrode employing conventional Nafion ionomer and 57.14 m2g1for the electrode incorporating HTAP-112 ionomer. The higher ECSA observed with the HTAP-112 ionomer-based electrode implies enhanced exposure of Pt active sites within the inner cavities and micro-regions of the catalyst layer to reactive gases. Conversely, the Nafion-based electrode exhibited a lower ECSA, indicative of reduced penetration of the ionomer into the catalyst's internal structure. Further optimization was conducted by varying the FC ratio, resulting in ECSA values for both Nafion and HTAP-112 ionomer-based electrodes. As depicted in Figure 10b, the ECSA for HTAP- 112 ionomer varied, yielding values of 79.10, 82.76, and 57.14 m2g1for VC ratios of 0.16, 0.33, and 0.66, respectively. In contrast, the corresponding ECSA values for Nafion ionomer are 38.11, 34.20, and 36.01 m2g1. The CV profile of all varying VC is given in Figure 11. These findings suggest that even a lower quantity of HTAP-112 ionomer remains effective for Pt / C catalysts.

[0112] After witnessing promising results from the utilization of HTAP-112 ionomer in ex-situ and in-situ analyses, a practical justification at the device level was undertaken by assessing a single cell of an HT-PEMFC. The in-situ ionomer-based electrode fabrication is pictorially represented in Figure 12.

[0113] Example 6: Electrochemical characterization of the full-cell PEMFCs

[0114] The membrane electrode assembly (MEA) with an area of 45 cm2was constructed by sandwiching electrodes containing in situ polymerized HTAP-112 ionomer with a polybenzimidazole (PBI) membrane. Catalyst coating was executed by preparing a catalyst ink with a maintained VC ratio of 0.40, followed by applying the catalyst layer via brush coating, ensuring a Pt loading of 1 mg cm2on both cathode and anode. For comparative analysis, an MEA composed of Pt / C as the anode and cathode catalyst, with the ionomer comprising an equal mixture of Nafion® and Polytetrafluoroethylene (PTFE) with the same VC ratio of 0.4, was prepared. All other parameters were consistent across both MEAs. Single-cell testing was conducted on the MEAs under H2-O2 and H2-air feed conditions, utilizing a fuel cell test station (Fuel Cell Technologies, USA) enabling systematic variations of various operational parameters.

[0115] Both fabricated MEAs were operated to record the current (I) - voltage (V) polarization plots at a high temperature of 160 °C. These plots are crucial for determining the feasibility of PEMFCs under practical operating conditions. Accordingly, Figure 13a and 13b depict the I- V polarization and power density plots obtained during the evaluation of the single cells under H2-O2 and H2-air feed conditions, respectively. The MEA with state-of-the-art catalyst Pt / C, utilizing the HTAP-112 ionomer formed via in situ polymerization, was compared with a MEA using conventional Nafion-PTFE ionomer. The polarization plots of the MEA in both feed conditions exhibit well-defined features spanning across the activation, ohmic, and mass transfer regions. Considering the general practical operating potential of the PEMFC as 0.60 V, the extracted current densities corresponding to this potential indicate values of 1.06 A cm'2with H2-O2 (Figure 13a, gray plot) for the MEA fabricated with HTAP-112 ionomer and 0.87 A cm-2for the MEA made with conventional Nafion-PTFE ionomer (Figure 13a black plot). The maximum power densities displayed by the MEA are 1.19 W cm-2for the HTAP- 112 ionomer-based MEA and 0.93 W cm-2for the Nafion-PTFE ionomer-based MEA under H2-O2 feeding conditions. The same MEAs were tested and analyzed under PE-air feeding conditions. The polarization profile is depicted in Figure 13b, showing current density values of 0.49 and 0.4 A cm-2at 0.6 V for the MEA based on HTAP-112 and Nafion-PTFE ionomers, respectively. The corresponding power densities are found to be 0.62 and 0.58 W cm-2under H2-air feed conditions. The superior performance of the HTAP-112 ionomer-based MEA was further subjected to a stability test for 24 h under H2-air feed conditions at a current of 19.89 A. After the 24 h stability test, a very small voltage drop rate of 0.6 mV / h was observed (Figure 13c). Additionally, the I-V polarization profile was compared before and after the stability test, revealing a slight reduction in current density at 0.6 V from 0.49 A cm-2to 0.47 A cm-2(Figure 13d). This further confirms the stable nature of HTAP-112 ionomer under HT-PEMFC operating conditions.

[0116] Furthermore, the issue of underutilized Pt active sites leading to mass activity loss is addressed by incorporating a high surface area 3D carbon support and integrating an in situ generated ionomer interface derived from pre-admitted low molecular weight monomers into the system. To this end, we have investigated the 3D-carbon-based Pt catalyst (Pt / 3DPDC), previously reported by our group for fast-activating LT-PEMFCs. The Pt / 3DPDC catalyst exhibits a 3D structure with Pt nanoparticles of size less than 3 nm finely dispersed throughout. The MEA, with an area of 45 cm2, is constructed using Pt / 3DPDC catalyst in both the cathode and anode with HTAP-112 ionomer. All other parameters, such as the VC ratio and membrane, are kept consistent with the Pt / C -based MEA. The corresponding I-V polarization plot is presented in Figure 14a. In the H2-O2 feeding environment, the MEA fabricated with PV3DPDC catalyst and HTAP-112 ionomer demonstrates a current density of 0.93 A cm-2and 0.42 A cm-2under H2-O2 and H2-air feeding conditions, respectively (Figure 14b). This observation further confirms the improved TPB formation facilitated by the 3D structure and in situ generated low molecular weight ionomer.

[0117] Example 7: Long Term Stability Test

[0118] A long-term stability test was performed over a period of 100 h at a constant current of 22.05 A. As shown in Figure 15, the membrane electrode assembly (MEA) exhibited excellent operational stability with a notably low voltage degradation rate of 0.22 mV h1throughout the test. These findings confirm the superior electrochemical durability of the inventive HTAP- 112 ionomer under extended high-temperature PEMFC conditions, highlighting its strong potential for reliable, long-term fuel cell applications. ADVANTAGES OF THE INVENTION

[0119] • The in situ generated, fluorine-free ionomer composition comprising low molecular weight, grows within the micro-regions and inner cavities of the catalyst support, where typically underutilized Pt active sites reside. The precursor monomers infiltrate these regions and polymerize to form ionomer networks within the inner regions, thereby optimizing the triple phase boundary for enhanced electrochemical surface area (ECSA).

[0120] • The membrane electrode assembly (MEA) based on the ionomer composition of the present invention reflects significantly high current densities as compared to conventional MEA based in Nafion.

[0121] • The ionomer composition enables reduction in the amount of the state-of-the-art Pt catalyst loading for cost-effective PEMFC assemblies for practical applications due to significant Pt catalyst utilization.

Claims

We claim:

1. An ionomer composition comprising of: a. at least one monomer in the range of 10-20 wt%; b. a cross linking agent in the range of 15-20 wt%; c. a weak acid in the range of 10-50 wt%; d. a binding agent in the range of 30-35 wt%; and e. a UV initiator in the range of 1-2 wt% of the total weight of the composition; wherein the monomer is a short chain low molecular weight monomer.

2. The ionomer composition as claimed in claim 1, wherein the monomer, cross -linking agent, and binding agent are mixed in a ratio in the range of 0.5:0.05:0.5 to 1:2:2.

3. The ionomer composition as claimed in claim 1, wherein the monomer is selected from hydroxypropyl methacrylate (HPMA), 2 -hydroxy ethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate or 2-hydroxybutyl methacrylate, and preferably is hydroxypropyl methacrylate (HPMA).

4. The ionomer composition as claimed in claim 1, wherein the crosslinking agent is selected from trimethylolpropane diallyl ether (TMDAE), N'-methylenebisacrylamide, Trimethylolpropane allyl ether 2-((allyloxy)methyl)-2-ethylbutan-l-ol), ethylene glycol dimethacrylate, poly (ethylene glycol) diacrylates, epichlorohydrin or glutaraldehyde, and preferably is trimethylolpropane diallyl ether (TMDAE).

5. The ionomer composition as claimed in claim 1 , wherein the binding agent is selected from 2-(trimethylammonio) ethyl methacrylate chloride (TMAEM) or (Acryloyloxy) ethyl trimethylammonium chloride, and preferably is 2-(trimethylammonio) ethyl methacrylate chloride (TMAEM).

6. The ionomer composition as claimed in claim 1, wherein the weak acid is selected from phosphoric acid (H3PO4), and acetic acid (CH3COOH), formic acid (HCOOH) and hydrofluoric acid (HF) and the UV initiator is selected from 2-hydroxy-2- methylpropiophenone (HMPP), Hydroxycyclohexyl phenyl ketone (Irgacure 184), 2- Benzyl-2-(dimethylamino)-4'-morpholinobutyrophenone (Irgacure 369), 2,4,6-Trimethylbenzoyldiphenylphosphine oxide (TPO), Benzoin methyl ether (BME), 2-Methyl- l-[4-(methylthio)phenyl]-2-morpholinopropan- l-one(Irgacure907) and Benzoin isobutyl ether (BIBE).

7. The ionomer composition as claimed in claim 1, wherein the monomer hydroxypropyl methacrylate (HPMA) in the range of 10-20 wt%; the cross linking agent trimethylolpropane diallyl ether (TMDAE) is in the range of 15-20 wt%; the weak acid phosphoric acid is in the range of 10-50 wt%; the binding agent 2-(trimethylammonio) ethyl methacrylate chloride (TMAEM) is in the range of 30-35 wt% and the UV initiator 2-hydroxy-2-methylpropiophenone (HMPP) is in the range of 1-2% of the total weight of the composition.

8. The ionomer composition as claimed in claim 1, wherein the monomer hydroxypropyl methacrylate (HPMA) is 14.55 wt%; cross linking agent trimethylolpropane diallyl ether (TMDAE) is 13.28 wt%; phosphoric acid is 34.69 wt%; phosphoric acid binding agent 2- (trimethylammonio) ethyl methacrylate chloride (TMAEM) is 31.08 wt% and the UV Initiator 2-hydroxy-2-methylpropiophenone (HMPP) is 0.27 wt%.

9. A process of preparing an ionomer composition comprising the steps of: a. mixing a low molecular weight monomer, crosslinking agent and binding agent in a suitable ratio; b. stirring the mixture of step (a) after adding a weak acid in the presence of a UV initiator; c. irradiating the solution of step (b) with UV radiation to obtain ionomer composition.

10. The process as claimed in claim 9, wherein the monomer is hydroxypropyl methacrylate (HPMA); the cross linking agent is trimethylolpropane diallyl ether (TMDAE); the binding agent is 2-(trimethylammonio) ethyl methacrylate chloride (TMAEM); the weak acid is phosphoric acid; and the UV initiator is 2-hydroxy-2-methylpropiophenone (HMPP), wherein the ratio of monomer, cross-linking agent, and binding agent is in the range of 0.5:0.05:0.5 to 1:2:2.

11. A process for preparing an electrode, comprising the steps of: i. preparing a solution of a transition metal catalyst in a suitable solvent;P_W0100775 ii. adding an ionomer composition comprising at least one monomer; a cross-linking agent, phosphoric acid, a phosphoric acid binding agent and a UV initiator wherein the monomer is a short chain low molecular weight monomer to the solution of step (i); iii. sonicating the mixture of step (ii) and coating the mixture uniformly over a gas diffusion layer or coating the mixture of step (ii) on the electrode with the gas diffusion layer; iv. irradiating the coating of step (iii) with UV radiation for in-situ generation of ionomers and obtaining the electrode; wherein the catalyst is selected from noble and / or non-noble transition metals and the solvent is selected from methanol, isopropanol, ethanol, and propanol.

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