Advanced Electrode Structures for Proton Exchange Membrane Fuel Cells: Current Status and Path Forward

Abstract

Proton exchange membrane fuel cells (PEMFCs) have demonstrated their viability as a promising candidate for clean energy applications. However, performance of conventional PEMFC electrodes, especially the cathode electrode, suffers from low catalyst utilization and sluggish mass transport due to the randomly distributed components and tortuous transport pathways. Development of alternative architectures in which the electrode structure is controlled across a range of length scales provides a promising path toward overcoming these limitations. Here, we provide a comprehensive review of recent research and development of advanced electrode structures, organized by decreasing length-scale from the millimeter-scale to the nanometer-scale. Specifically, advanced electrode structures are categorized into five unique architectures for specific functions: (1) macro-patterned electrodes for enhanced macro-scale mass transport, (2) micro-patterned electrodes for enhanced micro-scale mass transport, (3) electrospun electrodes with fiber-based morphology for enhanced in-plane proton transport and through-plane O₂ transport, (4) enhanced-porosity electrodes for improved oxygen transport through selective inclusion of void space, and (5) catalyst film electrodes for elimination of carbon corrosion and ionomer poisoning. The PEMFC performance results achieved from each alternative electrode structure are presented and tabulated for comparison with conventional electrode architectures. Moreover, analysis of mechanisms by which new electrode structures can improve performance is presented and discussed. Finally, an overview of current limitations and future research needs is presented to guide the development of electrode structures for next generation PEMFCs.

Graphical Abstract

Development of improved electrode architectures with the control of structure on length scales ranging from millimeters to nanometers could enable a new generation of fuel cells with increased performance and reduced cost. This paper presents an in-depth review and critical analysis of recent developments and future outlook on the design of advanced electrode structures.

Keywords

Proton exchange membrane fuel cells / Electrode structure / Membrane electrode assembly / Transport phenomena / Interface engineering / Catalyst layer

References

[1] Shukla, P.R., Skea, J., Slade, R. et al.: Climate change and land: an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems. Foreword Technical and Preface, 35–74 (2019).

[2] U.S. Energy Information Administration. Annual Energy Outlook, 2020.

[3] Sui PC, Zhu X, Djilali N. Modeling of PEM fuel cell catalyst layers: status and outlook. Electrochem. Energy Rev., 2019, 2: 428-466

[4] Guo YQ, Pan FW, Chen WM, et al.. The controllable design of catalyst inks to enhance PEMFC performance: a review. Electrochem. Energy Rev., 2021, 4: 67-100

[5] Papageorgopoulos, D.: Fuel Cell R&D Overview. 2019 Annual Merit Review and Peer Evaluation Meeting. 33 (2019).

[6] Papageorgopoulos, D.: Fuel Cell Technologies Overview. 2021 Annual Merit Review and Peer Evaluation Meeting. 1–72 (2021).

[7] Martinez U, Komini Babu S, Holby EF, et al.. Progress in the development of Fe-based PGM-free electrocatalysts for the oxygen reduction reaction. Adv. Mater., 2019, 31: 1-20

[8] Li JK, Sougrati MT, Zitolo A, et al.. Identification of durable and non-durable FeN_x sites in Fe-N-C materials for proton exchange membrane fuel cells. Nat. Catal., 2020, 4: 10-19

[9] He YH, Tan Q, Lu LL, et al.. Metal-nitrogen-carbon catalysts for oxygen reduction in PEM fuel cells: self-template synthesis approach to enhancing catalytic activity and stability. Electrochem. Energy Rev., 2019, 2: 231-251

[10] Xiao F, Wang YC, Wu ZP, et al.. Recent advances in electrocatalysts for proton exchange membrane fuel cells and alkaline membrane fuel cells. Adv. Mater., 2021, 33: 202006292

[11] Shen HJ, Thomas T, Rasaki SA, et al.. Oxygen reduction reactions of Fe-N-C catalysts: current status and the way forward. Electrochem. Energy Rev., 2019, 2: 252-276

[12] Cheng L, Khedekar K, Rezaei Talarposhti M, et al.. Mapping of heterogeneous catalyst degradation in polymer electrolyte fuel cells. Adv. Energy Mater., 2020, 10: 2000623

[13] Khedekar K, Rezaei Talarposhti M, Besli MM, et al.. Probing heterogeneous degradation of catalyst in PEM fuel cells under realistic automotive conditions with multi-modal techniques. Adv. Energy Mater., 2021, 11: 2101794

[14] Shao YY, Yin GP, Gao YZ. Understanding and approaches for the durability issues of Pt-based catalysts for PEM fuel cell. J. Power. Sour., 2007, 171: 558-566

[15] Zhang JW, Yuan YL, Gao L, et al.. Stabilizing Pt-based electrocatalysts for oxygen reduction reaction: fundamental understanding and design strategies. Adv. Mater., 2021, 33: 2006494

[16] Breitwieser M, Klingele M, Vierrath S, et al.. Tailoring the membrane-electrode interface in PEM fuel cells: a review and perspective on novel engineering approaches. Adv. Energy Mater., 2018, 8: 1701257

[17] Wang W, Lv F, Lei B, et al.. Tuning nanowires and nanotubes for efficient fuel-cell electrocatalysis. Adv. Mater., 2016, 28: 10117-10141

[18] Nie Y, Li L, Wei ZD. Recent advancements in Pt and Pt-free catalysts for oxygen reduction reaction. Chem. Soc. Rev., 2015, 44: 2168-2201

[19] Wang GL, Zou LL, Huang QH, et al.. Multidimensional nanostructured membrane electrode assemblies for proton exchange membrane fuel cell applications. J. Mater. Chem. A., 2019, 7: 9447-9477

[20] Yang YG, Zhou XY, Li B, et al.. Recent progress of the gas diffusion layer in proton exchange membrane fuel cells: material and structure designs of microporous layer. Int. J. Hydrog. Energy, 2021, 46: 4259-4282

[21] Park S, Lee JW, Popov BN. A review of gas diffusion layer in PEM fuel cells: materials and designs. Int. J. Hydrog. Energy, 2012, 37: 5850-5865

[22] Weber AZ, Borup RL, Darling RM, et al.. A critical review of modeling transport phenomena in polymer-electrolyte fuel cells. J. Electrochem. Soc., 2014, 161: F1254-F1299

[23] Paul MTY, Kim D, Saha MS, et al.. Patterning catalyst layers with microscale features by soft lithography techniques for proton exchange membrane fuel cells. ACS Appl. Energy Mater., 2020, 3: 478-486

[24] Shukla S, Domican K, Karan K, et al.. Analysis of low platinum loading thin polymer electrolyte fuel cell electrodes prepared by inkjet printing. Electrochim. Acta, 2015, 156: 289-300

[25] Debe MK. Nanostructured thin film electrocatalysts for PEM fuel cells: a tutorial on the fundamental characteristics and practical properties of NSTF catalysts. ECS Trans., 2012, 45: 47-68

[26] Aizawa M, Gyoten H. Effect of micro-patterned membranes on the cathode performances for PEM fuel cells under low humidity. J. Electrochem. Soc., 2013, 160: F417-F428

[27] Slack JJ, Gumeci C, Dale N, et al.. Nanofiber fuel cell MEAs with a PtCo/C cathode. J. Electrochem. Soc., 2019, 166: F3202-F3209

[28] Hong SJ, Hou M, Zhang HJ, et al.. A high-performance PEM fuel cell with ultralow platinum electrode via electrospinning and underpotential deposition. Electrochim. Acta, 2017, 245: 403-409

[29] Shukla S, Domican K, Secanell M. Effect of electrode patterning on PEM fuel cell performance using ink-jet printing method. ECS Trans., 2014, 64: 341-352

[30] Choi S, Jeon J, Chae JS, et al.. Single-step fabrication of a multiscale porous catalyst layer by the emulsion template method for low Pt-loaded proton exchange membrane fuel cells. ACS Appl. Energy Mater., 2021, 4: 4012-4020

[31] Wilson MS, Gottesfeld S. Thin-film catalyst layers for polymer electrolyte fuel cell electrodes. J. Appl. Electrochem., 1992, 22: 1-7

[32] M.S. Wilson, Membrane catalyst layer for fuel cells, US5211984A, 18 May 1993. https://image-ppubs.uspto.gov/dirsearch-public/print/downloadPdf/5211984

[33] Raistrick, I.D., Electrode assembly for use in a solid polymer electrolyte fuel cell. US4876115A. 24 Oct 1989. https://image-ppubs.uspto.gov/dirsearch-public/print/downloadPdf/4876115

[34] Litster S, McLean G. PEM fuel cell electrodes. J. Power. Sour., 2004, 130: 61-76

[35] Owejan JP, Owejan JE, Gu WB. Impact of platinum loading and catalyst layer structure on PEMFC performance. J. Electrochem. Soc., 2013, 160: F824-F833

[36] Ahn CY, Ahn J, Kang SY, et al.. Enhancement of service life of polymer electrolyte fuel cells through application of nanodispersed ionomer. Sci. Adv., 2020, 6: eaaw0870

[37] Eguchi M, Baba K, Onuma T, et al.. Influence of ionomer/carbon ratio on the performance of a polymer electrolyte fuel cell. Polymers, 2012, 4: 1645-1656

[38] Liu YX, Murphy MW, Baker DR, et al.. Proton conduction and oxygen reduction kinetics in PEM fuel cell cathodes: effects of ionomer-to-carbon ratio and relative humidity. J. Electrochem. Soc., 2009, 156: B970-B980

[39] Santangelo P, Cannio M, Romagnoli M. Review of catalyst-deposition techniques for PEMFC electrodes. Tecnica Italiana Italian J. Eng. Sci., 2019, 63: 65-72

[40] Sassin MB, Garsany Y, Gould BD, et al.. Fabrication method for laboratory-scale high-performance membrane electrode assemblies for fuel cells. Anal. Chem., 2017, 89: 511-518

[41] Lee E, Kim DH, Pak C. Effects of cathode catalyst layer fabrication parameters on the performance of high-temperature polymer electrolyte membrane fuel cells. Appl. Surf. Sci., 2020, 510: 145461

[42] Uchida M, Park YC, Kakinuma K, et al.. Effect of the state of distribution of supported Pt nanoparticles on effective Pt utilization in polymer electrolyte fuel cells. Phys. Chem. Chem. Phys., 2013, 15: 11236

[43] Mauger SA, Neyerlin KC, Yang-Neyerlin AC, et al.. Gravure coating for roll-to-roll manufacturing of proton-exchange-membrane fuel cell catalyst layers. J. Electrochem. Soc., 2018, 165: F1012-F1018

[44] Bodner M, García HR, Steenberg T, et al.. Enabling industrial production of electrodes by use of slot-Die coating for HT-PEM fuel cells. Int. J. Hydrog. Energy, 2019, 44: 12793-12801

[45] Shao MH, Merzougui B, Shoemaker K, et al.. Tungsten carbide modified high surface area carbon as fuel cell catalyst support. J. Power. Sour., 2011, 196: 7426-7434

[46] Breitwieser M, Klingele M, Britton B, et al.. Improved Pt-utilization efficiency of low Pt-loading PEM fuel cell electrodes using direct membrane deposition. Electrochem. Commun., 2015, 60: 168-171

[47] Li DG, Pan YT, Wang XJ, et al.. Effect of the catalyst metal content on PEMFC durability. ECS Trans., 2019, 92: 589-594

[48] Kumaraguru, S.: Durable High Power Membrane Electrode Assembly with Low Pt Loading, General Motors, DOE hydrogen program, 2019. https://www.hydrogen.energy.gov/docs/hydrogenprogramlibraries/pdfs/review20/fc156_kumaraguru_2020_p.pdf

[49] Cullen DA, Neyerlin KC, Ahluwalia RK, et al.. New Roads and challenges for fuel cells in heavy-duty transportation. Nat. Energy, 2021, 6: 462-474

[50] Marcinkoski, J.: DOE Advanced Truck Technologies, Subsection of the Electrified Powertrain Roadmap Technical Targets for Hydrogen-Fueled Long-Haul Tractor-Trailer Trucks. Record #: 19006, 31 October 2019. https://www.hydrogen.energy.gov/pdfs

[51] Weber AZ, Kusoglu A. Unexplained transport resistances for low-loaded fuel-cell catalyst layers. J. Mater. Chem. A., 2014, 2: 17207-17211

[52] More K, Borup R, Reeves K. Identifying contributing degradation phenomena in PEM fuel cell membrane electride assemblies via electron microscopy. ECS Trans., 2006, 3: 717-733

[53] Ramaswamy, N.: Durable Fuel Cell MEA through Immobilization of Catalyst Particle and Membrane Chemical Stabilizer. U.S. Department of Energy Annual Merit Review and Peer Evaluation Meeting (2022).

[54] She ZW, Kibsgaard J, Dickens CF, et al.. Combining theory and experiment in electrocatalysis: Insights into materials design. Science, 2017, 355: eaad4998

[55] Sun XY, Yu HM, Zhou L, et al.. Influence of platinum dispersity on oxygen transport resistance and performance in PEMFC. Electrochim. Acta, 2020, 332: 135474

[56] Chen JK, Liu HM, Huang YA, et al.. High-rate roll-to-roll stack and lamination of multilayer structured membrane electrode assembly. J. Manuf. Process., 2016, 23: 175-182

[57] Bing YH, Liu HS, Zhang L, et al.. Nanostructured Pt-alloy electrocatalysts for PEM fuel cell oxygen reduction reaction. Chem. Soc. Rev., 2010, 39: 2184-2202

[58] Park YC, Tokiwa H, Kakinuma K, et al.. Effects of carbon supports on Pt distribution, ionomer coverage and cathode performance for polymer electrolyte fuel cells. J. Power. Sour., 2016, 315: 179-191

[59] Holdcroft S. Fuel cell catalyst layers: a polymer science perspective. Chem. Mater., 2014, 26: 381-393

[60] Komini Babu S, Spernjak D, Dillet J, et al.. Spatially resolved degradation during startup and shutdown in polymer electrolyte membrane fuel cell operation. Appl. Energy, 2019, 254 113659

[61] De Bruijn FA, Dam VAT, Janssen GJM. Review: durability and degradation issues of PEM fuel cell components. Fuel Cells., 2008, 8: 3-22

[62] Shao YY, Liu J, Wang Y, et al.. Novel catalyst support materials for PEM fuel cells: current status and future prospects. J. Mater. Chem., 2009, 19: 46-59

[63] Ren XF, Lv QY, Liu LF, et al.. Current progress of Pt and Pt-based electrocatalysts used for fuel cells. Sustain. Energy Fuels., 2020, 4: 15-30

[64] Schuler T, Chowdhury A, Freiberg AT, et al.. Fuel-cell catalyst-layer resistance via hydrogen limiting-current measurements. J. Electrochem. Soc., 2019, 166: F3020-F3031

[65] Kongkanand A, Mathias MF. The priority and challenge of high-power performance of low-platinum proton-exchange membrane fuel cells. J. Phys. Chem. Lett., 2016, 7: 1127-1137

[66] Fan JT, Chen M, Zhao ZL, et al.. Bridging the gap between highly active oxygen reduction reaction catalysts and effective catalyst layers for proton exchange membrane fuel cells. Nat. Energy, 2021, 6: 475-486

[67] Das PK, Li XG, Liu ZS. Analysis of liquid water transport in cathode catalyst layer of PEM fuel cells. Int. J. Hydrog. Energy, 2010, 35: 2403-2416

[68] Srouji AK, Zheng LJ, Dross R, et al.. The role of water management on the oxygen transport resistance in polymer electrolyte fuel cell with ultra-low precious metal loading. J. Power. Sour., 2017, 364: 92-100

[69] Eikerling M. Water management in cathode catalyst layers of PEM fuel cells. J. Electrochem. Soc., 2006, 153: E58-E70

[70] Meier JC, Galeano C, Katsounaros I, et al.. Design criteria for stable Pt/C fuel cell catalysts. Beilstein J. Nanotechnol., 2014, 5: 44-67

[71] Cherevko S, Kulyk N, Mayrhofer KJJ. Durability of platinum-based fuel cell electrocatalysts: dissolution of bulk and nanoscale platinum. Nano Energy, 2016, 29: 275-298

[72] Linse N, Gubler L, Scherer GG, et al.. The effect of platinum on carbon corrosion behavior in polymer electrolyte fuel cells. Electrochim. Acta, 2011, 56: 7541-7549

[73] Speder J, Zana A, Spanos I, et al.. Comparative degradation study of carbon supported proton exchange membrane fuel cell electrocatalysts: the influence of the platinum to carbon ratio on the degradation rate. J. Power. Sour., 2014, 261: 14-22

[74] Ahluwalia RK, Peng JK, Wang X, et al.. Long-term stability of nanostructured thin film electrodes at operating potentials. J. Electrochem. Soc., 2017, 164: F306-F320

[75] Ahluwalia RK, Arisetty S, Peng JK, et al.. Dynamics of particle growth and electrochemical surface area loss due to platinum dissolution. J. Electrochem. Soc., 2014, 161: F291-F304

[76] Towne S, Viswanathan V, Holbery J, et al.. Fabrication of polymer electrolyte membrane fuel cell MEAs utilizing inkjet print technology. J. Power. Sour., 2007, 171: 575-584

[77] Therdthianwong A, Saenwiset P, Therdthianwong S. Cathode catalyst layer design for proton exchange membrane fuel cells. Fuel, 2012, 91: 192-199

[78] Song CH, Park JS. Membrane–electrode assemblies with patterned electrodes for proton-exchange membrane fuel cells. Chem. Lett., 2018, 47: 196-199

[79] Heinz O, Aghajani M, Greenberg AR, et al.. Surface-patterning of polymeric membranes: fabrication and performance. Curr. Opin. Chem. Eng., 2018, 20: 1-12

[80] O’Hayre R, Lee SJ, Cha SW, et al.. A sharp peak in the performance of sputtered platinum fuel cells at ultra-low platinum loading. J. Power. Sources, 2002, 109: 483-493

[81] Zeis R, Mathur A, Fritz G, et al.. Platinum-plated nanoporous gold: an efficient, low Pt loading electrocatalyst for PEM fuel cells. J. Power. Sour., 2007, 165: 65-72

[82] Choi WC, Kim JD, Woo SI. Modification of proton conducting membrane for reducing methanol crossover in a direct-methanol fuel cell. J. Power. Sour., 2001, 96: 411-414

[83] Kim JH, Sohn J, Cho JH, et al.. Surface modification of Nafion membranes using atmospheric-pressure low-temperature plasmas for electrochemical applications. Plasma Process. Polym., 2008, 5: 377-385

[84] Bae JW, Cho YH, Sung YE, et al.. Performance enhancement of polymer electrolyte membrane fuel cell by employing line-patterned Nafion membrane. J. Ind. Eng. Chem., 2012, 18: 876-879

[85] Jang S, Her M, Kim S, et al.. Membrane/electrode interface design for effective water management in alkaline membrane fuel cells. ACS Appl. Mater. Interfaces, 2019, 11: 34805-34811

[86] Aizawa M, Gyoten H, Salah A, et al.. Pillar structured membranes for suppressing cathodic concentration overvoltage in PEMFCs at elevated temperature/low relative humidity. J. Electrochem. Soc., 2010, 157: B1844-B1851

[87] Kim SM, Kang YS, Ahn C, et al.. Prism-patterned Nafion membrane for enhanced water transport in polymer electrolyte membrane fuel cell. J. Power. Sour., 2016, 317: 19-24

[88] Pu LJ, Jiang JJ, Yuan T, et al.. Performance improvement of passive direct methanol fuel cells with surface-patterned Nafion® membranes. Appl. Surf. Sci., 2015, 327: 205-212

[89] Maruf SH, Wang L, Greenberg AR, et al.. Use of nanoimprinted surface patterns to mitigate colloidal deposition on ultrafiltration membranes. J. Membr. Sci., 2013, 428: 598-607

[90] Ning FD, Bai C, Qin JQ, et al.. Great improvement in the performance and lifetime of a fuel cell using a highly dense, well-ordered, and cone-shaped Nafion array. J. Mater. Chem. A., 2020, 8: 5489-5500

[91] Chen M, Wang M, Yang ZY, et al.. A novel catalyst layer structure based surface-patterned Nafion® membrane for high-performance direct methanol fuel cell. Electrochim. Acta, 2018, 263: 201-208

[92] Ahn CY, Jang S, Cho YH, et al.. Guided cracking of electrodes by stretching prism-patterned membrane electrode assemblies for high-performance fuel cells. Sci. Rep., 2018, 8: 1-9

[93] Cho H, Moon Kim S, Sik Kang Y, et al.. Multiplex lithography for multilevel multiscale architectures and its application to polymer electrolyte membrane fuel cell. Nat. Commun., 2015, 6: 1-8

[94] Jang S, Kim M, Kang YS, et al.. Facile multiscale patterning by creep-assisted sequential imprinting and fuel cell application. ACS Appl. Mater. Interfaces, 2016, 8: 11459-11465

[95] Paul MTY, Saha MS, Qi WL, et al.. Microstructured membranes for improving transport resistances in proton exchange membrane fuel cells. Int. J. Hydrog. Energy, 2020, 45: 1304-1312

[96] Kang S, Bae G, Kim SK, et al.. Performance of a MEA using patterned membrane with a directly coated electrode by the bar-coating method in a direct methanol fuel cell. Int. J. Hydrog. Energy, 2018, 43: 11386-11396

[97] Barambu NU, Bilad MR, Wibisono Y, et al.. Membrane surface patterning as a fouling mitigation strategy in liquid filtration: a review. Polymers, 2019, 11: 1687

[98] Omosebi A, Besser RS. Patterning the cathode catalyst layer-membrane interface of a PEMFC for elevated power density. ECS Trans., 2011, 41: 883-889

[99] Chi WS, Jeon Y, Park SJ, et al.. Fabrication of surface-patterned membranes by means of a ZnO nanorod templating method for polymer electrolyte membrane fuel-cell applications. ChemPlusChem, 2014, 79: 1109-1115

[100] Koh JK, Jeon Y, Cho YI, et al.. A facile preparation method of surface patterned polymer electrolyte membranes for fuel cell applications. J. Mater. Chem. A., 2014, 2: 8652-8659

[101] Jeon Y, Kim DJ, Koh JK, et al.. Interface-designed membranes with shape-controlled patterns for high-performance polymer electrolyte membrane fuel cells. Sci. Rep., 2015, 5: 16394

[102] Khan A, Nath BK, Chutia J. Conical nano-structure arrays of platinum cathode catalyst for enhanced cell performance in PEMFC (proton exchange membrane fuel cell). Energy, 2015, 90: 1769-1774

[103] Omosebi A, Besser RS. Ultra-low mass sputtered and conventional catalyst layers on plasma-etched nafion for PEMFC applications. Fuel Cells., 2017, 17: 762-769

[104] Yakovlev YV, Nováková J, Kúš P, et al.. Highly developed nanostructuring of polymer-electrolyte membrane supported catalysts for hydrogen fuel cell application. J. Power. Sour., 2019, 439: 227084

[105] Seol C, Jang S, Lee J, et al.. High-performance fuel cells with a plasma-etched polymer electrolyte membrane with microhole arrays. ACS Sustain. Chem. Eng., 2021, 9: 5884-5894

[106] Omosebi A, Besser RS. Electron beam assisted patterning and dry etching of nafion membranes. J. Electrochem. Soc., 2011, 158: D603-D610

[107] Lee DH, Jo W, Yuk S, et al.. In-plane channel-structured catalyst layer for polymer electrolyte membrane fuel cells. ACS Appl. Mater. Interfaces, 2018, 10: 4682-4688

[108] Spernjak D, Mukundan R, Borup RL, et al.. Enhanced water management of polymer electrolyte fuel cells with additive-containing microporous layers. ACS Appl. Energy Mater., 2018, 1: 6006-6017

[109] Murata S, Imanishi M, Hasegawa S, et al.. Vertically aligned carbon nanotube electrodes for high current density operating proton exchange membrane fuel cells. J. Power. Sour., 2014, 253: 104-113

[110] Zhang CK, Yu HM, Li YK, et al.. Supported noble metals on hydrogen-treated TiO₂ nanotube arrays as highly ordered electrodes for fuel cells. Chemsuschem, 2013, 6: 659-666

[111] Wang C, Waje M, Wang X, et al.. Proton exchange membrane fuel cells with carbon nanotube based electrodes. Nano Lett., 2004, 4: 345-348

[112] Wu HJ, Yuan T, Huang QH, et al.. Polypyrrole nanowire networks as anodic micro-porous layer for passive direct methanol fuel cells. Electrochim. Acta, 2014, 141: 1-5

[113] Hezarjaribi M, Jahanshahi M, Rahimpour A, et al.. Gas diffusion electrode based on electrospun Pani/CNF nanofibers hybrid for proton exchange membrane fuel cells (PEMFC) applications. Appl. Surf. Sci., 2014, 295: 144-149

[114] Sun RL, Xia ZX, Shang L, et al.. Hierarchically ordered arrays with platinum coated PANI nanowires for highly efficient fuel cell electrodes. J. Mater. Chem. A., 2017, 5: 15260-15265

[115] Xia ZX, Wang SL, Jiang LH, et al.. Bio-inspired construction of advanced fuel cell cathode with Pt anchored in ordered hybrid polymer matrix. Sci. Rep., 2015, 5: 16100

[116] Fu XD, Wang SL, Xia ZX, et al.. Aligned polyaniline nanorods in situ grown on gas diffusion layer and their application in polymer electrolyte membrane fuel cells. Int. J. Hydrog. Energy, 2016, 41: 3655-3663

[117] Chen M, Wang M, Yang ZY, et al.. High performance and durability of order-structured cathode catalyst layer based on TiO₂@PANI core-shell nanowire arrays. Appl. Surf. Sci., 2017, 406: 69-76

[118] Choi J, Wycisk R, Zhang WJ, et al.. High conductivity perfluorosulfonic acid nanofiber composite fuel-cell membranes. Chemsuschem, 2010, 3: 1245-1248

[119] Ballengee JB, Pintauro PN. Composite fuel cell membranes from dual-nanofiber electrospun mats. Macromolecules, 2011, 44: 7307-7314

[120] Park JH, Ju YW, Park SH, et al.. Effects of electrospun polyacrylonitrile-based carbon nanofibers as catalyst support in PEMFC. J. Appl. Electrochem., 2009, 39: 1229-1236

[121] Zhang WJ, Pintauro PN. High-performance nanofiber fuel cell electrodes. Chemsuschem, 2011, 4: 1753-1757

[122] Waldrop K, Wycisk R, Pintauro PN. Application of electrospinning for the fabrication of proton-exchange membrane fuel cell electrodes. Curr. Opin. Electrochem., 2020, 21: 257-264

[123] Chan S, Jankovic J, Susac D, et al.. Electrospun carbon nanofiber catalyst layers for polymer electrolyte membrane fuel cells: fabrication and optimization. J. Mater. Sci., 2018, 53: 11633-11647

[124] Álvarez G, Alcaide F, Cabot PL, et al.. Electrochemical performance of low temperature PEMFC with surface tailored carbon nanofibers as catalyst support. Int. J. Hydrog. Energy, 2012, 37: 393-404

[125] Chung S, Shin D, Choun M, et al.. Improved water management of Pt/C cathode modified by graphitized carbon nanofiber in proton exchange membrane fuel cell. J. Power. Sour., 2018, 399: 350-356

[126] Mooste M, Kibena-Põldsepp E, Vassiljeva V, et al.. Electrocatalysts for oxygen reduction reaction based on electrospun polyacrylonitrile, styrene–acrylonitrile copolymer and carbon nanotube composite fibres. J. Mater. Sci., 2019, 54: 11618-11634

[127] Wang Y, Li G, Jin JH, et al.. Hollow porous carbon nanofibers as novel support for platinum-based oxygen reduction reaction electrocatalysts. Int. J. Hydrog. Energy, 2017, 42: 5938-5947

[128] Cavaliere S, Subianto S, Savych I, et al.. Dopant-driven nanostructured loose-tube SnO₂ architectures: alternative electrocatalyst supports for proton exchange membrane fuel cells. J. Phys. Chem. C, 2013, 117: 18298-18307

[129] Chen SX, Du HD, Wei YP, et al.. Fine-tuning the cross-sectional architecture of antimony-doped tin oxide nanofibers as Pt catalyst support for enhanced oxygen reduction activity. Int. J. Electrochem. Sci., 2017, 12: 6221-6231

[130] Ji Y, Cho YI, Jeon Y, et al.. Design of active Pt on TiO₂ based nanofibrous cathode for superior PEMFC performance and durability at high temperature. Appl. Catal. B Environ., 2017, 204: 421-429

[131] Kayarkatte MK, Delikaya Ö, Roth C. Polyacrylic acid-Nafion composites as stable catalyst support in PEM fuel cell electrodes. Mater. Today Commun., 2018, 16: 8-13

[132] Simotwo SK, Kalra V. Study of Co-electrospun nafion and polyaniline nanofibers as potential catalyst support for fuel cell electrodes. Electrochim. Acta, 2016, 198: 156-164

[133] Nabil Y, Cavaliere S, Harkness IA, et al.. Novel niobium carbide/carbon porous nanotube electrocatalyst supports for proton exchange membrane fuel cell cathodes. J. Power. Sour., 2017, 363: 20-26

[134] Kim M, Kwon C, Eom K, et al.. Electrospun Nb-doped TiO₂ nanofiber support for Pt nanoparticles with high electrocatalytic activity and durability. Sci. Rep., 2017, 7: 44411

[135] Sun YY, Cui LR, Gong J, et al.. Design of a catalytic layer with hierarchical proton transport structure: the role of nafion nanofiber. ACS Sustain. Chem. Eng., 2019, 7: 2955-2963

[136] Hwang M, Elabd YA. Impact of ionomer resistance in nanofiber-nanoparticle electrodes for ultra-low platinum fuel cells. Int. J. Hydrog. Energy, 2019, 44: 6245-6256

[137] Wang XH, Richey FW, Wujcik KH, et al.. Effect of polytetrafluoroethylene on ultra-low platinum loaded electrospun/electrosprayed electrodes in proton exchange membrane fuel cells. Electrochim. Acta, 2014, 139: 217-224

[138] Wei M, Jiang M, Liu XB, et al.. Graphene-doped electrospun nanofiber membrane electrodes and proton exchange membrane fuel cell performance. J. Power Sources, 2016, 327: 384-393

[139] Choi S, Yuk S, Lee DH, et al.. Rugged catalyst layer supported on a Nafion fiber mat for enhancing mass transport of polymer electrolyte membrane fuel cells. Electrochim. Acta, 2018, 268: 469-475

[140] Gao YY, Hou M, He L, et al.. A new insight into the stability of nanofiber electrodes used in proton exchange membrane fuel cells. J. Energy Chem., 2020, 42: 126-132

[141] Brodt M, Wycisk R, Pintauro PN. Nanofiber electrodes with low platinum loading for high power hydrogen/air PEM fuel cells. J. Electrochem. Soc., 2013, 160: F744-F749

[142] Brodt M, Han T, Dale N, et al.. Fabrication, in-situ performance, and durability of nanofiber fuel cell electrodes. J. Electrochem. Soc., 2014, 162: F84-F91

[143] Brodt M, Wycisk R, Dale N, et al.. Power output and durability of electrospun fuel cell fiber cathodes with PVDF and nafion/PVDF binders. J. Electrochem. Soc., 2016, 163: F401-F410

[144] Chintam K, Waldrop K, Baker AM, et al.. Improved water management of electrospun nanofiber membrane electrode assemblies at high current densities measured in operando using neutron radiography. ECS Trans., 2019, 92: 125-134

[145] Slack JJ, Brodt M, Cullen DA, et al.. Impact of polyvinylidene fluoride on nanofiber cathode structure and durability in proton exchange membrane fuel cells. J. Electrochem. Soc., 2020, 167 054517

[146] Chevalier S, Lavielle N, Hatton BD, et al.. Novel electrospun gas diffusion layers for polymer electrolyte membrane fuel cells: Part I. Fabrication, morphological characterization, and in situ performance. J. Power. Sources, 2017, 352: 272-280

[147] Chan S, Jankovic J, Susac D, et al.. Electrospun carbon nanofiber catalyst layers for polymer electrolyte membrane fuel cells: structure and performance. J. Power. Sour., 2018, 392: 239-250

[148] Zeng YC, Zhang HJ, Wang ZQ, et al.. Nano-engineering of a 3D-ordered membrane electrode assembly with ultrathin Pt skin on open-walled PdCo nanotube arrays for fuel cells. J. Mater. Chem. A., 2018, 6: 6521-6533

[149] Qi MM, Zeng YC, Hou M, et al.. Free-standing and ionomer-free 3D platinum nanotrough fiber network electrode for proton exchange membrane fuel cells. Appl. Catal. B Environ., 2021, 298: 120504

[150] Chen H, Snyder JD, Elabd YA. Electrospinning and solution properties of nafion and poly(acrylic acid). Macromolecules, 2008, 41: 128-135

[151] Kabir S, Van Cleve T, Khandavalli S, et al.. Toward optimizing electrospun nanofiber fuel cell catalyst layers: microstructure and Pt accessibility. ACS Appl. Energy Mater., 2021, 4: 3341-3351

[152] Khandavalli S, Sharma-Nene N, Kabir S, et al.. Toward optimizing electrospun nanofiber fuel cell catalyst layers: polymer–particle interactions and spinnability. ACS Appl. Polym. Mater., 2021, 3: 2374-2384

[153] Dong B, Gwee L, Salas-de la Cruz D, et al.. Super proton conductive high-purity nafion nanofibers. Nano Lett., 2010, 10: 3785-3790

[154] Ramaswamy N, Gu WB, Ziegelbauer JM, et al.. Carbon support microstructure impact on high current density transport resistances in PEMFC cathode. J. Electrochem. Soc., 2020, 167: 064515

[155] Mohseninia A, Kartouzian D, Eppler M, et al.. Influence of structural modification of micro-porous layer and catalyst layer on performance and water management of PEM fuel cells: hydrophobicity and porosity. Fuel Cells., 2020, 20: 469-476

[156] Mohseninia A, Kartouzian D, Schlumberger R, et al.. Enhanced water management in PEMFCs: perforated catalyst layer and microporous layers. Chemsuschem, 2020, 13: 2931-2934

[157] Zlotorowicz A, Jayasayee K, Dahl PI, et al.. Tailored porosities of the cathode layer for improved polymer electrolyte fuel cell performance. J. Power Sources, 2015, 287: 472-477

[158] Cho YH, Jung N, Kang YS, et al.. Improved mass transfer using a pore former in cathode catalyst layer in the direct methanol fuel cell. Int. J. Hydrog. Energy, 2012, 37: 11969-11974

[159] Kim OH, Cho YH, Kang SH, et al.. Ordered macroporous platinum electrode and enhanced mass transfer in fuel cells using inverse opal structure. Nat. Commun., 2013, 4: 2473

[160] Zhao JS, He XM, Wang L, et al.. Addition of NH₄HCO₃ as pore-former in membrane electrode assembly for PEMFC. Int. J. Hydrog. Energy, 2007, 32: 380-384

[161] Fischer A, Jindra J, Wendt H. Porosity and catalyst utilization of thin layer cathodes in air operated PEM-fuel cells. J. Appl. Electrochem., 1998, 28: 277-282

[162] Henkensmeier D, Dang QK, Nambi Krishnan N, et al.. Ortho-Dichlorobenzene as a pore modifier for PEMFC catalyst electrodes and dense Nafion membranes with one porous surface. J. Mater. Chem., 2012, 22: 14602-14607

[163] Yu Z, Carter RN, Zhang J. Measurements of pore size distribution, porosity, effective oxygen diffusivity, and tortuosity of PEM fuel cell electrodes. Fuel Cells., 2012, 12: 557-565

[164] Lee MC, Tan C, Ravanfar R, et al.. Ultrastable water-in-oil high internal phase emulsions featuring interfacial and biphasic network stabilization. ACS Appl. Mater. Interfaces, 2019, 11: 26433-26441

[165] Kim SM, Ahn CY, Cho YH, et al.. High-performance fuel cell with stretched catalyst-coated membrane: one-step formation of cracked electrode. Sci. Rep., 2016, 6: 26503

[166] Yoon Y. Effect of pore structure of catalyst layer in a PEMFC on its performance. Int. J. Hydrog. Energy, 2003, 28: 657-662

[167] White RT, Wu A, Najm M, et al.. 4D in situ visualization of electrode morphology changes during accelerated degradation in fuel cells by X-ray computed tomography. J. Power. Sour., 2017, 350: 94-102

[168] Hwang GS, Kim H, Lujan R, et al.. Phase-change-related degradation of catalyst layers in proton-exchange-membrane fuel cells. Electrochim. Acta, 2013, 95: 29-37

[169] Guo QH, Qi ZG. Effect of freeze-thaw cycles on the properties and performance of membrane-electrode assemblies. J. Power. Sour., 2006, 160: 1269-1274

[170] Kumano N, Kudo K, Suda A, et al.. Controlling cracking formation in fuel cell catalyst layers. J. Power. Sour., 2019, 419: 219-228

[171] Huang DC, Yu PJ, Liu FJ, et al.. Effect of dispersion solvent in catalyst ink on proton exchange membrane fuel cell performance. Int. J. Electrochem. Sci., 2011, 6: 2551-2565

[172] Tranter TG, Tam M, Gostick JT. The effect of cracks on the in-plane electrical conductivity of PEFC catalyst layers. Electroanalysis, 2019, 31: 619-623

[173] Hizir FE, Ural SO, Kumbur EC, et al.. Characterization of interfacial morphology in polymer electrolyte fuel cells: micro-porous layer and catalyst layer surfaces. J. Power. Sour., 2010, 195: 3463-3471

[174] Yin Y, Li RT, Bai FQ, et al.. Ionomer migration within PEMFC catalyst layers induced by humidity changes. Electrochem. Commun., 2019, 109: 106590

[175] Ramani D, Singh Y, Orfino FP, et al.. Characterization of membrane degradation growth in fuel cells using X-ray computed tomography. J. Electrochem. Soc., 2018, 165: F3200-F3208

[176] Babu SK, Atkinson RWIII, Papandrew AB, et al.. Vertically oriented polymer electrolyte nanofiber catalyst support for thin film proton-exchange membrane fuel cell electrodes. ChemElectroChem, 2015, 2: 1752-1759

[177] Wang Y, Ruiz Diaz DF, Chen KS, et al.. Materials, technological status, and fundamentals of PEM fuel cells: a review. Mater. Today, 2020, 32: 178-203

[178] Debe MK. Electrocatalyst approaches and challenges for automotive fuel cells. Nature, 2012, 486: 43-51

[179] Çögenli MS, Mukerjee S, Yurtcan AB. Membrane electrode assembly with ultra low platinum loading for cathode electrode of PEM fuel cell by using sputter deposition. Fuel Cells., 2015, 15: 288-297

[180] Yang GQ, Yu SL, Mo JK, et al.. Impacts of catalyst nanolayers on water permeation and swelling of polymer electrolyte membranes. J. Power. Sour., 2020, 448: 227582

[181] Ergul-Yilmaz B, Yang ZW, Perry ML, et al.. Microstructural evolution and ORR activity of nanocolumnar platinum thin films with different mass loadings grown by high pressure sputtering. J. Electrochem. Soc., 2020, 167: 134514

[182] Lai YC, Huang KL, Tsai CH, et al.. Sputtered Pt loadings of membrane electrode assemblies in proton exchange membrane fuel cells. Int. J. Energy Res., 2012, 36: 918-927

[183] Gruber D, Ponath N, Müller J, et al.. Sputter-deposited ultra-low catalyst loadings for PEM fuel cells. J. Power. Sour., 2005, 150: 67-72

[184] Ostroverkh A, Johanek V, Dubau M, et al.. Novel fuel cell MEA based on Pt-C deposited by magnetron sputtering. ECS Trans., 2017, 80: 225-230

[185] Cullen DA, Lopez-Haro M, Bayle-Guillemaud P, et al.. Linking morphology with activity through the lifetime of pretreated PtNi nanostructured thin film catalysts. J. Mater. Chem. A., 2015, 3: 11660-11667

[186] Steinbach AJ, Allen JS, Borup RL, et al.. Anode-design strategies for improved performance of polymer-electrolyte fuel cells with ultra-thin electrodes. Joule, 2018, 2: 1297-1312

[187] Jiang SF, Yi BL, Zhang CK, et al.. Vertically aligned carbon-coated titanium dioxide nanorod arrays on carbon paper with low platinum for proton exchange membrane fuel cells. J. Power. Sour., 2015, 276: 80-88

[188] Jiang SF, Yi BL, Zhang HJ, et al.. Vertically aligned titanium nitride nanorod arrays as supports of platinum–palladium–cobalt catalysts for thin-film proton exchange membrane fuel cell electrodes. ChemElectroChem, 2016, 3: 734-740

[189] Inaba M, Suzuki T, Hatanaka T, et al.. Fabrication and cell analysis of a Pt/SiO₂Platinum thin film electrode. J. Electrochem. Soc., 2015, 162: F634-F638

[190] Jiang SF, Yi BL, Cao LS, et al.. Development of advanced catalytic layer based on vertically aligned conductive polymer arrays for thin-film fuel cell electrodes. J. Power. Sour., 2016, 329: 347-354

[191] Mardle P, Ji XC, Wu J, et al.. Thin film electrodes from Pt nanorods supported on aligned N-CNTs for proton exchange membrane fuel cells. Appl. Catal. B Environ., 2020, 260: 118031

[192] Tian Z, Lim SH, Poh CK, et al.. A highly order-structured membrane electrode assembly with vertically aligned carbon nanotubes for ultra-low Pt loading PEM fuel cells. Adv. Energy Mater., 2011, 1: 1205-1214

[193] Hu LM, Zhang MX, Komini Babu S, et al.. Ionic conductivity over metal/water interfaces in ionomer-free fuel cell electrodes. ChemElectroChem, 2019, 6: 2659-2666

[194] Zenyuk IV, Litster S. Modeling ion conduction and electrochemical reactions in water films on thin-film metal electrodes with application to low temperature fuel cells. Electrochim. Acta, 2014, 146: 194-206

[195] Galbiati S, Morin A, Pauc N. Supportless platinum nanotubes array by atomic layer deposition as PEM fuel cell electrode. Electrochim. Acta, 2014, 125: 107-116

[196] Kim JM, Jo A, Lee KA, et al.. Conformation-modulated three-dimensional electrocatalysts for high-performance fuel cell electrodes. Sci. Adv., 2021, 7: eabe9083

[197] Fidiani E, AlKahfi AZ, Absor MAU, et al.. Au-doped PtAg nanorod array electrodes for proton-exchange membrane fuel cells. ACS Appl. Energy Mater., 2022, 5: 14979-14989

[198] Wei ZX, Su KH, Sui S, et al.. High performance polymer electrolyte membrane fuel cells (PEMFCs) with gradient Pt nanowire cathodes prepared by decal transfer method. Int. J. Hydrog. Energy, 2015, 40: 3068-3074

[199] Galbiati S, Morin A, Pauc N. Nanotubes array electrodes by Pt evaporation: Half-cell characterization and PEM fuel cell demonstration. Appl. Catal. B Environ., 2015, 165: 149-157

[200] Marconot O, Pauc N, Buttard D, et al.. Vertically aligned platinum copper nanotubes as PEM fuel cell cathode: elaboration and fuel cell test. Fuel Cells., 2018, 18: 723-730

[201] Zeng YC, Shao ZG, Zhang HJ, et al.. Nanostructured ultrathin catalyst layer based on open-walled PtCo bimetallic nanotube arrays for proton exchange membrane fuel cells. Nano Energy, 2017, 34: 344-355

[202] Paulus UA, Veziridis Z, Schnyder B, et al.. Fundamental investigation of catalyst utilization at the electrode/solid polymer electrolyte interface. J. Electroanal. Chem., 2003, 541: 77-91

[203] An SJ, Litster S. In situ, ionic conductivity measurement of ionomer/binder-free Pt catalyst under fuel cell operating condition. ECS Trans., 2013, 58: 831-839

[204] Pan SF, Qin JQ, Ning FD, et al.. Well-dispersed nafion array prepared by the freeze-drying method to effectively improve the performance of proton exchange membrane fuel cells. ACS Sustain. Chem. Eng., 2021, 9: 16770-16777

[205] Babu, S.K., Spendelow, J.S., Mukundan, R.: Coaxial nanowire electrode. US20200321626A1, 8 Oct 2020. https://image-ppubs.uspto.gov/dirsearch-public/print/downloadPdf/20200321626

[206] Borup, R., Weber, A.: FC-PAD: Fuel Cell Performance and Durability Consortium, DOE Fuel Cell Technologies Office Annual Merit Review. (2019). https://www.energy.gov/eere/fuelcells/fc-pad-fuel-cell-consortium-performance-and-durability

[207] Cuynet S, Caillard A, Kaya-Boussougou S, et al.. Membrane patterned by pulsed laser micromachining for proton exchange membrane fuel cell with sputtered ultra-low catalyst loadings. J. Power. Sources, 2015, 298: 299-308

[208] Jiao K, Xuan J, Du Q, et al.. Designing the next generation of proton-exchange membrane fuel cells. Nature, 2021, 595: 361-369

Funding

Los Alamos National Laboratory(2020200DR)

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The Author(s)