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Proton exchange membrane fuel cells (PEMFCs) which have high efficiency have attracted attention as one of the most promising energy conversion devices. Currently the catalysts in PEMFCs are mainly carbon supported noble metals where the support can afford the electron transport environment to improve catalyst efficiency and decrease catalyst loss by strengthening catalyst–support bonding [1]. Due to high electrical conductivity and surface area, carbon-based catalyst supports are widely used in PEMFCs. However, the high electric fields applied to the fuel cell can easily cause carbon corrosion and further accelerate catalyst loss. New alternative support materials are needed to reduce costs and increase the lifetime of PEMFC electrodes. Recently, silica-based supports such as silicon oxide [2, 3] and silicon carbide [4] have been considered feasible as catalyst supports due to efficient catalyst utilization and their resistance to carbon corrosion. As a silica-based material, hydrophilic silica nanosheets (SN) derived from cheap natural vermiculite [5] is for the first time to be combined with carbon black (CB) as a catalyst support in this work. SN-CB supported platinum (Pt) catalysts were prepared according to different weight ratios of SN and CB using a modified polyol reduction method [6]. After 18000-cycle accelerated stress test (AST), as shown in Fig. 1a and b, the electrochemical surface area (ECSA) of Pt/SN2-CB3 (the weight ratio of SN to CB is 2: 3) decays from 23.7 to 22.5 m2/g (only 4.8% degradation) compared to Pt/CB (25.8% degradation from 16.0 to 11.9 m2/g). Meanwhile, Pt/SN2-CB3 shows comparable initial onset potential (0.850 V) and high half-wave potential (0.654 V) compared to 0.881 V onset potential and 0.625 V half-wave potential for Pt/CB as shown in Fig. 1c and d. The half-wave potential of Pt/SN2-CB3 after AST test demonstrated the addition of SN into the support can result in a stable oxygen reduction reaction (ORR) durability. The possible reason why the ECSA, ORR activity and durability of SN-CB supported platinum catalysts are enhanced is that the synergic interactions among carbon, silica nanosheets and Pt nanoparticles may hinder carbon corrosion, Pt agglomeration and dissolution [2]. Different weight ratios between SN and CB and the functionalized SNs are currently being tested and the real fuel cell data will be presented. Reference [1] Y.-J. Wang, D.P. Wilkinson, J. Zhang, Noncarbon support materials for polymer electrolyte membrane fuel cell electrocatalysts, Chemical reviews, 111 (2011) 7625-7651. [2] P. Dhanasekaran, A. Shukla, S.V. Selvaganesh, S. Mohan, S. Bhat, Silica-decorated carbon-Pt electrocatalyst synthesis via single-step polyol method for superior polymer electrolyte fuel cell performance, durability and stack operation under low relative humidity, Journal of Power Sources, 438 (2019) 226999. [3] P. Dhanasekaran, S.V. Selvaganesh, A. Rathishkumar, S. Bhat, Designing self-humidified platinum anchored silica decorated carbon electrocatalyst for boosting the durability and performance of polymer electrolyte fuel cell stack, International Journal of Hydrogen Energy, 46 (2021) 8143-8155. [4] L. Dong, J. Zang, J. Su, Y. Jia, Y. Wang, J. Lu, X. Xu, Oxidized carbon/nano-SiC supported platinum nanoparticles as highly stable electrocatalyst for oxygen reduction reaction, International journal of hydrogen energy, 39 (2014) 16310-16317. [5] Z. Guo, J. Chen, J.J. Byun, R. Cai, M. Perez-Page, M. Sahoo, Z. Ji, S.J. Haigh, S.M. Holmes, High-performance polymer electrolyte membranes incorporated with 2D silica nanosheets in high-temperature proton exchange membrane fuel cells, Journal of Energy Chemistry, 64 (2022) 323-334. [6] Z. Ji, M. Perez-Page, J. Chen, R.G. Rodriguez, R. Cai, S.J. Haigh, S.M. Holmes, A structured catalyst support combining electrochemically exfoliated graphene oxide and carbon black for enhanced performance and durability in low-temperature hydrogen fuel cells, Energy, 226 (2021) 120318. Figure 1

High-temperature proton exchange membrane fuel cell (HT-PEMFC) is promising with its low demand for hydrogen purity, simple water management, and high waste heat utilization [1][2]. Although polybenzimidazole (PBI), as a typical high-temperature fuel cell membrane, has been developed for a long period, it still has defects such as phosphoric acid leaching and insufficient mechanical properties under high acid doping level [3][4]. With its unique 2D hexagonal grid structure and its electron cloud arrangement, single-layer graphene (SLG) can block the passage of any atoms [5]. However, hydrogen protons can easily penetrate SLG through a unique intermediate state mechanism to make it have excellent proton conductivity [6]. SLG's high proton conductivity combined with its excellent mechanical properties and thermal conductivity make it an ideal material for blocking phosphoric acid leaching. The SLG prepared by the chemical vapor deposition (CVD) method was transferred to the surface of catalyst layer of electrodes by the wet chemical transfer method. Due to the rupture and incompleteness of the SLG during the transfer process, the coverage rate of the SLG on the electrode surface is about 55%. This incomplete coverage facilitates small quantities of phosphoric acid leaching from PBI membrane to electrodes, which increases the three-phase boundary area and improves the performance of the HT-PEMFC. After 70 hours of accelerated stress testing (AST), the peak power density of membrane-electrode-assembly (MEA) with SLG on both sides of the cathode and anode can reach 480 mW cm-2, while the peak power density of MEA based on pure PBI membrane is only 249 mW cm-2. The quantification of phosphoric acid in the electrode by Lab based X-ray micro-computed tomography and the Raman spectroscopic mapping of the MEA cross-section shows that SLG can mitigate the leaching of phosphoric acid in the PBI film and improve the durability of HT-PEMFC. Graphene oxide (GO) is a low-cost application of graphene. Its doping in the PBI membrane can also reduce the leaching of phosphoric acid through enhancing the interaction between phosphoric acid and the PBI membrane [7]. A reactor based on 3D printing was designed so that natural graphite flakes can be used for electrochemical exfoliation to achieve rapid, safe, environmentally friendly, and mass production of GO. The electrochemically exfoliated (E)GO is doped in the PBI membrane. The 0.5%, 1% and 2% EGO loadings in the PBI membrane increased the peak power density by 13.8%, 24.4% and 29.2%, respectively. [1] Y.-L. Ma, J.S. Wainright, M.H. Litt, R.F. Savinell, Conductivity of PBI Membranes for High-Temperature Polymer Electrolyte Fuel Cells, Journal of The Electrochemical Society. 151 (2004) A8. https://doi.org/10.1149/1.1630037/XML. [2] H. Su, S. Pasupathi, B. Bladergroen, V. Linkov, B.G. Pollet, Optimization of gas diffusion electrode for polybenzimidazole-based high temperature proton exchange membrane fuel cell: Evaluation of polymer binders in catalyst layer, International Journal of Hydrogen Energy. 38 (2013) 11370–11378. https://doi.org/10.1016/J.IJHYDENE.2013.06.107. [3] S. Galbiati, A. Baricci, A. Casalegno, R. Marchesi, Degradation in phosphoric acid doped polymer fuel cells : A 6000 h parametric investigation, International Journal of Hydrogen Energy. 38 (2013) 6469–6480. https://doi.org/10.1016/j.ijhydene.2013.03.012. [4] S.H. Eberhardt, F. Marone, M. Stampanoni, F.N. Büchi, T.J. Schmidt, Quantifying phosphoric acid in high-temperature polymer electrolyte fuel cell components by X-ray tomographic microscopy, Journal of Synchrotron Radiation. 21 (2014) 1319–1326. https://doi.org/10.1107/S1600577514016348. [5] S. Hu, M. Lozada-Hidalgo, F.C. Wang, A. Mishchenko, F. Schedin, R.R. Nair, E.W. Hill, D.W. Boukhvalov, M.I. Katsnelson, R.A.W. Dryfe, I. V. Grigorieva, H.A. Wu, A.K. Geim, Proton transport through one-atom-thick crystals, Nature. 516 (2014) 227–230. https://doi.org/10.1038/nature14015. [6] S.M. Holmes, P. Balakrishnan, V.S. Kalangi, X. Zhang, M. Lozada-Hidalgo, P.M. Ajayan, R.R. Nair, 2D Crystals Significantly Enhance the Performance of a Working Fuel Cell, Advanced Energy Materials. 7 (2017) 1–7. https://doi.org/10.1002/aenm.201601216. [7] J. Li, X. Zeng, T. Ren, E. van der Heide, The Preparation of Graphene Oxide and Its Derivatives and Their Application in Bio-Tribological Systems, Lubricants 2014, Vol. 2, Pages 137-161. 2 (2014) 137–161. https://doi.org/10.3390/LUBRICANTS2030137.

The high-temperature proton exchange membrane fuel cell (HT-PEMFC) conducts protons through the hydrogen bond network established by the polymer and phosphoric acid (PA), which reduces the dependence on humidity and allows its operating temperature to be higher than 100°C [1]. A higher operating temperature is conducive to improve catalyst activity, reducing carbon dioxide adsorption on the catalyst thus reducing the requirement for hydrogen purity, and convenient water management [2]. As the most widely commercialized HT-PEMFC proton exchange membrane material, the performance and durability of Polybenzimidazole (PBI) still need to be improved. In particular, it has insufficient proton conductivity, insufficient mechanical properties, and phosphoric acid leaching issues under high acid doping level [3] [4] [5]. The doping of functionalized graphene oxide in the PBI membrane can build additional proton transfer channels, promote proton hopping and act as a trap for PA to reduce its leaching by virtue of abundant functional groups of functionalized GO [6] [7] [8]. Among the groups that can be used for functionalization, the phosphoric acid group has become one of the most promising due to its strong hydrogen bonding and water retention ability [9] [10] [11]. Phosphonated graphene oxide (PGO) is usually synthesized by further phosphonation of GO obtained by chemical exfoliation [6] [7]. Chemical exfoliation methods usually require the long-term action of strong acids and strong oxidants [12]. The safety and environmental issues caused by those methods can not be underestimated. And the two-step synthesis method of PGO has a long reaction period. This work achieved the rapid, safe, and large-yield production of electrochemically exfoliated PGO by using a 3D printed reactor, ammonium dihydrogen phosphate as the electrolyte and natural graphite flakes as the raw material. The two-step electrochemical exfoliation method of producing GIC with concentrated sulfuric acid as the first electrolyte is also used to synthesize electrochemical exfoliated (E)GO. 1.5wt% EGO or PGO was doped in the PBI membrane to explore the effect of different GO on the performance and durability of the PBI- membrane-based HT-PEMFC. Compared with pure PBI, the doping of EGO and PGO increases the peak power density of HT-PEMFC by 17.4% and 35.4%, respectively. [1] Y.-L. Ma, J.S. Wainright, M.H. Litt, R.F. Savinell, Journal of The Electrochemical Society 2004, 151, A8. [2] H. Su, S. Pasupathi, B. Bladergroen, V. Linkov, B.G. Pollet, International Journal of Hydrogen Energy 2013, 38, 11370. [3] S. Galbiati, A. Baricci, A. Casalegno, R. Marchesi, International Journal of Hydrogen Energy 2013, 38, 6469. [4] S.H. Eberhardt, F. Marone, M. Stampanoni, F.N. Büchi, T.J. Schmidt, Journal of Synchrotron Radiation 2014, 21, 1319. [5] Q. He, X. Yang, W. Chen, S. Mukerjee, B. Koel, S. Chen, Physical Chemistry Chemical Physics 2010, 12, 12544. [6] J. Yang, C. Liu, L. Gao, J. Wang, Y. Xu, R. He, RSC Advances 2015, 5, 101049. [7] C. Xu, Y. Cao, R. Kumar, X. Wu, X. Wang, K. Scott, Journal of Materials Chemistry 2011, 21, 11359. [8] Y. Cai, Z. Yue, S.X.-J. of A.P. Science, undefined 2017, Wiley Online Library 2017, 134, 44986. [9] E. Abouzari-Lotf, H. Ghassemi, A. Shockravi, T. Zawodzinski, D. Schiraldi, Polymer 2011, 52, 4709. [10] E. Abouzari-Lotf, M. Zakeri, M.M. Nasef, M. Miyake, P. Mozarmnia, N.A. Bazilah, N.F. Emelin, A. Ahmad, Journal of Power Sources 2019, 412, 238. [11] S. Some, I. Shackery, S.J. Kim, S.C. Jun, Chemistry - A European Journal 2015, 21, 15480. [12] C. Xu, Y. Cao, R. Kumar, X. Wu, X. Wang, K. Scott, Journal of Materials Chemistry 2011, 21, 11359.

The electrolyte plays an important role in the Membrane Electrode Assembly (MEA) of Polymeric Electrolyte Membranes Fuel Cells, (PEMFCs), having three main functions, to act as ion conductor, electronic insulator and a separator for the reactant gases [1]. The electrolyte is a Proton Exchange Membrane and Nafion is the most widely used polymeric membrane in this technology. However, because its particular structure it requires a good hydration to lead a high proton conductivity, which limit the operating temperature to lower than 100 oC. Poly[2,2′-m-(phenylene)-5,5′-benzimidazole (PBI) membrane doped with Phosphoric Acid, has been presented as an alternative to Nafion membranes allowing higher operating temperatures, 200oC, which enhance the kinetics of the reactions. However, during the operation of High Temperature Fuel Cells (HT-PEMFCs) these membranes suffer Phosphoric Acid leaching leading to a low proton conductivity and degradation of the fuel cell [2]. The 2D honeycomb lattice of Graphene provides this material particular properties such as high surface area, exceptionally high electrical conductivity, good chemical and thermal stability and excellent barrier properties, which make it a potential material for a large number of applications. In addition to this [1], Hu. et al. [3] have demonstrated that Single Layer Graphene present a high proton conductivity being at the same time a barrier for other elements, which makes this material a potential electrolyte for PEMFC. However, SLG has some drawbacks notably due to the complex process to produce it and its high cost. These limitations leave an open window to Graphene based materials such as Graphene Oxide, which shows very attractive properties to act as filler in Nafion and PBI membranes due to its chemical functionalization and its non-porous structure, which provides additional resistance for mass transport and increases the tortuosity of the permeation pathways leading to higher selectivity [1]. Here we will describe the work carried out at University of Manchester incorporating SLG and GO composite membranes into the MEA of both PEM Fuel Cells, Low Temperature (LT-PEMFC) and HT-PEMFC. The addition of the SLG produced by CVD into the MEA of LT-PEMFC has demonstrated no change in the proton conductivity, supporting the hypothesis that SLG is a good proton conductor. In addition, for a particular LT-PEMFC, Direct Methanol Fuel Cells (DMFC), a decreasing of the methanol crossover has found leading a significant enhancement of the power density [4]. SLG has been also incorporated into the MEA of HT-PEMFC, which use PBI membrane instead of Nafion, to evaluate its proton conductivity and barrier properties, this time to stop the Phosphoric Acid leaching. Although positive results have been reported by adding SLG into the MEAs, a different approach has been conducted by the development of GO-composite membranes also for both type of PEMFC. Exfoliated Graphene Oxide has been synthesized by electrochemical exfoliation of graphite and has been incorporated as a filler into two different of matrix polymer, Nafion and PBI, to evaluate their performance in both PEMFC, high and low temperature. References: [1] Perez-Page Maria, Sahoo Madhumita, Holmes, M Stuart. Single Layer 2D Crystals for Electrochemical Applications of Ion Exchange Membranes and Hydrogen Evolution Catalyst. Advance Materials Interfaces (2019) 6, 1801838. [2] S. H. Eberhardt, M. Toulec, F. Marone, M. Stampanoni, F. N. Buchi and T. J. Schmidt. Dynamic Operation of HT-OEFC: In-Operando Imaging of Phosphoric Acid Profiles and (Re)distribution. Journal of The Electrochemical Society, (2015), 162, 3, F310-F316. [3] S. Hu, M. Lozada-Hidalgo, F. C. Wang, A. Mishchenko, F. Schedin, R. R. Nair, E. W. Hill, D. W. Boukhvalov, M. I. Katsnelson, R. A. W. Dryfe, I. V. Grigorieva, H. A. Wu, A. K. Geim. Proton transport one-atom-thick crystals. Nature (2014), 516, 227. [4] Stuart M. Holmes, Orabhuraj Balakrishnan, Vasu. S. Kalangi, Xiang Zhang, Marcelo Lozada-Hidalgo, Pulickel M Ajayan, Rahul R. Nair. 2D Crystals Significantly Enhance the Performance of a Working Fuel Cell. Advance Energy Materials, 7, (2017).

Graphene, a two-dimensional (2D) structure of honeycomb lattice material with long-range π-conjugation, is an ideal catalyst support material due to its large surface area, excellent electrical conductivity, good mechanical and electrochemical stability [1]. It has already been reported that platinum nanoparticles (PtNPs) supported on reduced graphene oxide (rGO), is limited by van der Waals force resulting in the restacked rGO flakes during the reduction process, thereby hindering the transport of fuel gas to approach Pt active sites [2, 3]. To overcome this issue, several publications have successfully developed PtNPs catalyst supported on rGO and carbon black (CB) hybrid supporting materials [4]. The synergistic effect between rGO and CB could enhance its activity for oxygen reduction reaction through controlling PtNPs size as well as improve its durability by preventing the agglomeration and corrosion of supporting materials [3]. However, Hummers GO leads to environmental and safety issues (use KMnO4, strong oxidizing agents and concentrated H2SO4) as well as a long-time preparation with high cost [2]. Our previous research has already developed a novel graphene-based material prepared by electrochemical exfoliation of graphite, which is faster, more environmentally friendly and has a high yield, intercalated by CB as a bi-support and achieved 50% improvement performance compared with Pt/CB. To further improve catalyst activity, some research proposed that the introduction of nitrogen, especially graphitic N and pyridinic N, on the surface of carbon materials could improve ORR activity and electronic conductivity by changing the local electronic structure as well as polarization of the graphene network with smaller energy band gap [3, 5]. However, the effect and comparation of nitrogen doped rEGO intercalated by CB (NrEGO-CB) and nitrogen doped both EGO and CB (NrEGO-NCB) as bi-support materials to improve the performance of the hydrogen fuel cell have not been studied. In this work, EGO and EGO-CB was doped with nitrogen by hydrothermal treatment with urea as a nitrogen precursor in a Teflon-steel autoclave. Pt catalysts were synthesized by a modified polyol reduction method. Successful preliminary results can be observed in Fig 1, which shows that PtNPs supported on NrEGO-CB with ratio of 2 to 3 has a maximum power density of 1.2 W cm-2. It is more than 4 times compared with that 0.3 W cm-2 of Pt/CB. References [1] Haibo Wang, Thandavarayan Maiyalagan, Xin Wang. Review on recent progress in nitrogen-doped graphene: synthesis, characterization, and its potential applications. ACS Catalysis. 2012. 2 (5): 781-794. [2] Erwan Bertin, Adrian Münzer, Sven Reichenberger, Rene Streubel, Thomas Vinnay, Hartmut Wiggers, Christof Schulz, Stephan Barcikowski, Galina Marzun. Durability study of platinum nanoparticles supported on gas-phase synthesized graphene in oxygen reduction reaction conditions. Applied Surface Science. 2019. 467-468, 1181-1186. [3] W.H. Lee, H.N. Yang, K.W. Park, B.S. Choi, S.C. Yi, W.J. Kim. Synergistic effect of boron/nitrogen co-doping into graphene and intercalation of carbon black for Pt-BCN-Gr/CB hybrid catalyst on cell performance of polymer electrolyte membrane fuel cell. Energy. 2016. 96: 314-324. [4] Yujing Li, Yongjia Li, Enbo Zhu, Tait McLouth, Chin-Yi Chiu, Xiaoqing Huang, Yu Huang. Stabilization of high-Performance oxygen reduction reaction Pt electrocatalyst supported on reduced graphene oxide/carbon black composite. Journal of The American Chemical Society. 2012. 134: 12326-12329. [5] Yue Jiang, Jia Zhang, Yuanhang Qin, Dongfang Niu, Xinsheng Zhang, Li Niu, Xinggui Zhou, Tianhong Lu, Weikang Yuan. Ultrasonic synthesis of nitrogen-doped carbon nanofibers as platinum catalyst support for oxygen reduction. Journal of Power Source. 2011. 196: 9356-9360. Figure 1

Since its discovery in 2004, Graphene has been widely study for different applications, noticeable for electrochemical energy devices, due to its excellent properties as a barrier material, electrical conductivity or high surface area. However, it is still an expensive material since it cannot be produced in a large scale. Graphene based materials such as Graphene oxide (GO) or Reduced Graphene Oxide (rGO) also present similar properties than Graphene and can be produce in a more economical way [1]. However, traditional method to produce GO, Hummer’s method, which base on chemical exfoliation of graphite, is a long and tedious process which requires the use of strong oxidants and hazardous chemicals leading environmental pollution that cannot be repaired [2,3]. Recently, electrochemical exfoliation of graphite to produce GO has attracted more and more attention due its environmental protection, low price, easy process and high efficiency [4-7]. Since natural graphite is mostly in the form of flakes and its tiny size is not conducive to its direct use in electrochemical exfoliation, currently, electrochemical exfoliation is mostly made of graphite foil, graphite rod and other graphite processed products. These materials are obtained by using processes such as chemical, thermodynamic, and mechanical compression, leading in physical or chemical changes that alter their original properties or structure. There are also some attempts to use natural graphite flakes for electrochemical exfoliation [8,9]. However, this makes electrochemical exfoliation require more voltage, longer time and less yield. In this work, we present novel design reactor to perform electrochemical exfoliation using natural graphite flakes as raw materials. By using ammonium sulphate as electrolyte, electrochemical exfoliation of natural graphite flakes can be done at low voltage with short time. This achievement also enables the comparison of electrochemical exfoliation products with different raw materials (graphite foil and natural graphite flakes) at the same exfoliation voltage and the same exfoliation time. We explored the properties of the product by raman spectroscopy, ultraviolet–visible spectroscopy (UV-VIS), fourier-transform Infrared Spectroscopy (FT-IR), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), Thermogravimetric analysis (TGA), four-probe method and contact angle measurement. We have found that by combining natural graphite flakes with the reactor, the product obtained is significantly different from the exfoliated product based on graphite foil, achieving better oxidation, better dispersion in deionized water, more defects and greater yield. In addition, the special structure of the reactor allows the exfoliation time to be controlled, and we also compare the products obtained at different exfoliation times. The Exfoliated Graphene Oxide (EGO) obtained it has been used as a filler material in proton exchange membranes for hydrogen fuel cells as well as a support material for electrocalyst to enhance the kinetics for the reactions which take place in these fuel cells. References: [1] Perreault F, De Faria A F, Elimelech M. Environmental applications of graphene-based nanomaterials[J]. Chemical Society Reviews, 2015, 44(16): 5861-5896. [2] Eigler S. Controlled Chemistry Approach to the Oxo‐Functionalization of Graphene[J]. Chemistry–A European Journal, 2016, 22(21): 7012-7027. [3] Eigler S, Hirsch A. Chemistry with graphene and graphene oxide—challenges for synthetic chemists[J]. Angewandte Chemie International Edition, 2014, 53(30): 7720-7738. [4] Gurzęda B, Florczak P, Kempiński M, et al. Synthesis of graphite oxide by electrochemical oxidation in aqueous perchloric acid[J]. Carbon, 2016, 100: 540-545. [5] Su C Y, Lu A Y, Xu Y, et al. High-quality thin graphene films from fast electrochemical exfoliation[J]. ACS nano, 2011, 5(3): 2332-2339. [6] Tian Z, Yu P, Lowe S E, et al. Facile electrochemical approach for the production of graphite oxide with tunable chemistry[J]. Carbon, 2017, 112: 185-191. [7] Liu J, Poh C K, Zhan D, et al. Improved synthesis of graphene flakes from the multiple electrochemical exfoliation of graphite rod[J]. Nano Energy, 2013, 2(3): 377-386. [8] Yu P, Tian Z, Lowe S E, et al. Mechanically-assisted electrochemical production of graphene oxide[J]. Chemistry of Materials, 2016, 28(22): 8429-8438. [9] Lowe S E, Shi G, Zhang Y, et al. Scalable Production of Graphene Oxide Using a 3D-Printed Packed-Bed Electrochemical Reactor with a Boron-Doped Diamond Electrode[J]. ACS Applied Nano Materials, 2019, 2(2): 867-878.

The electrolyte plays an important role in the Membrane Electrode Assembly (MEA) of Polymeric Electrolyte Membranes Fuel Cells, (PEMFCs), having three main functions, to act as ion conductor, electronic insulator and a separator for the reactant gases [1]. The electrolyte is a Proton Exchange Membrane and Nafion is the most widely used polymeric membrane in this technology. However, because its particular structure it requires a good hydration to lead a high proton conductivity, which limit the operating temperature to lower than 100 oC. Poly[2,2′-m-(phenylene)-5,5′-benzimidazole (PBI) membrane doped with Phosphoric Acid, has been presented as an alternative to Nafion membranes allowing higher operating temperatures, 200oC, which enhance the kinetics of the reactions. However, during the operation of High Temperature Fuel Cells (HT-PEMFCs) these membranes suffer Phosphoric Acid leaching leading to a low proton conductivity and degradation of the fuel cell [2]. The 2D honeycomb lattice of Graphene provides this material particular properties such as high surface area, exceptionally high electrical conductivity, good chemical and thermal stability and excellent barrier properties, which make it a potential material for a large number of applications. In addition to this [1], Hu. et al. [3] have demonstrated that Single Layer Graphene present a high proton conductivity being at the same time a barrier for other elements, which makes this material a potential electrolyte for PEMFC. However, SLG has some drawbacks notably due to the complex process to produce it and its high cost. These limitations leave an open window to Graphene based materials such as Graphene Oxide, which shows very attractive properties to act as filler in Nafion and PBI membranes due to its chemical functionalization and its non-porous structure, which provides additional resistance for mass transport and increases the tortuosity of the permeation pathways leading to higher selectivity [1]. Here we will describe the work carried out at University of Mancheschester incorporating SLG and GO composite membranes into the MEA of both PEM Fuel Cells, Low Temperature (LT-PEMFC) and HT-PEMFC. The addition of the SLG produced by CVD into the MEA of LT-PEMFC has demonstrated no change in the proton conductivity, supporting the hypothesis that SLG is a good proton conductor. In addition, for a particular LT-PEMFC, Direct Methanol Fuel Cells (DMFC), a decreasing of the methanol crossover has found leading a significant enhancement of the power density [4]. SLG has been also incorporated into the MEA of HT-PEMFC, which use PBI membrane instead of Nafion, to evaluate its proton conductivity and barrier properties, this time to stop the Phosphoric Acid leaching. Although positive results have been reported by adding SLG into the MEAs, a different approach has been conducted by the development of GO-composite membranes also for both type of PEMFC. Exfoliated Graphene Oxide has been synthesized by electrochemical exfoliation of graphite and has been incorporated as a filler into two different of matrix polymer, Nafion and PBI, to evaluate their performance in both PEMFC, high and low temperature. References: [1] Perez-Page Maria, Sahoo Madhumita, Holmes, M Stuart. Single Layer 2D Crystals for Electrochemical Applications of Ion Exchange Membranes and Hydrogen Evolution Catalyst. Advance Materials Interfaces (2019) 6, 1801838. [2] S. H. Eberhardt, M. Toulec, F. Marone, M. Stampanoni, F. N. Buchi and T. J. Schmidt. Dynamic Operation of HT-OEFC: In-Operando Imaging of Phosphoric Acid Profiles and (Re)distribution. Journal of The Electrochemical Society, (2015), 162, 3, F310-F316. [3] S. Hu, M. Lozada-Hidalgo, F. C. Wang, A. Mishchenko, F. Schedin, R. R. Nair, E. W. Hill, D. W. Boukhvalov, M. I. Katsnelson, R. A. W. Dryfe, I. V. Grigorieva, H. A. Wu, A. K. Geim. Proton transport one-atom-thick crystals. Nature (2014), 516, 227. [4] Stuart M. Holmes, Orabhuraj Balakrishnan, Vasu. S. Kalangi, Xiang Zhang, Marcelo Lozada-Hidalgo, Pulickel M Ajayan, Rahul R. Nair. 2D Crystals Significantly Enhance the Performance of a Working Fuel Cell. Advance Energy Materials, 7, (2017).