Single Cobalt Sites Dispersed in Hierarchically Porous Nanofiber Networks for Durable and High‐Power PGM‐Free Cathodes in Fuel Cells

Increasing catalytic activity and durability of atomically dispersed metal–nitrogen–carbon (M–N–C) catalysts for the oxygen reduction reaction (ORR) cathode in proton‐exchange‐membrane fuel cells remains a grand challenge. Here, a high‐power and durable Co–N–C nanofiber catalyst synthesized through electrospinning cobalt‐doped zeolitic imidazolate frameworks into selected polyacrylonitrile and poly(vinylpyrrolidone) polymers is reported. The distinct porous fibrous morphology and hierarchical structures play a vital role in boosting electrode performance by exposing more accessible active sites, providing facile electron conductivity, and facilitating the mass transport of reactant. The enhanced intrinsic activity is attributed to the extra graphitic N dopants surrounding the CoN4 moieties. The highly graphitized carbon matrix in the catalyst is beneficial for enhancing the carbon corrosion resistance, thereby promoting catalyst stability. The unique nanoscale X‐ray computed tomography verifies the well‐distributed ionomer coverage throughout the fibrous carbon network in the catalyst. The membrane electrode assembly achieves a power density of 0.40 W cm−2 in a practical H2/air cell (1.0 bar) and demonstrates significantly enhanced durability under accelerated stability tests. The combination of the intrinsic activity and stability of single Co sites, along with unique catalyst architecture, provide new insight into designing efficient PGM‐free electrodes with improved performance and durability.

[1]  Yi Li,et al.  Advanced Electrocatalysis for Energy and Environmental Sustainability via Water and Nitrogen Reactions , 2020, Advanced materials.

[2]  Drew C. Higgins,et al.  Supported and coordinated single metal site electrocatalysts , 2020 .

[3]  D. Cullen,et al.  Atomically Dispersed Single Ni Site Catalysts for Nitrogen Reduction toward Electrochemical Ammonia Synthesis Using N 2 and H 2 O , 2020, Small Methods.

[4]  Yanghua He,et al.  Atomically dispersed metal-nitrogen-carbon catalysts for fuel cells: advances in catalyst design, electrode performance, and durability improvement. , 2020, Chemical Society reviews.

[5]  G. Bender,et al.  Improving the bulk gas transport of Fe-N-C platinum group metal-free nanofiber electrodes via electrospinning for fuel cell applications , 2020 .

[6]  Jianhong Liu,et al.  Highly efficient utilization of single atoms via constructing 3D and free-standing electrodes for CO2 reduction with ultrahigh current density , 2020 .

[7]  Lijun Yang,et al.  Cobalt/zinc dual-sites coordinated with nitrogen in nanofibers enabling efficient and durable oxygen reduction reaction in acidic fuel cells , 2020, Journal of Materials Chemistry A.

[8]  P. Atanassov,et al.  Iron-Nitrogen-Carbon Catalysts for Proton Exchange Membrane Fuel Cells , 2020 .

[9]  X. Lou,et al.  Advanced Electrocatalysts for the Oxygen Reduction Reaction in Energy Conversion Technologies , 2020, Joule.

[10]  Yanghua He,et al.  Engineering Local Coordination Environments of Atomically Dispersed and Heteroatom‐Coordinated Single Metal Site Electrocatalysts for Clean Energy‐Conversion , 2019, Advanced Energy Materials.

[11]  D. Cullen,et al.  Thermally Driven Structure and Performance Evolution of Atomically Dispersed Fe-N4 Sites for Oxygen Reduction. , 2019, Angewandte Chemie.

[12]  S. Litster,et al.  High Power Density PGM-Free Cathodes for Polymer Electrolyte Fuel Cells. , 2019, ACS applied materials & interfaces.

[13]  S. Mukerjee,et al.  Recent Insights into the Oxygen-Reduction Electrocatalysis of Fe/N/C Materials , 2019, ACS Catalysis.

[14]  Junliang Zhang,et al.  Insight into the Rapid Degradation Behavior of Non-precious-metal Fe-N-C Electrocatalysts Based Proton Exchange Membrane Fuel Cells. , 2019, ACS applied materials & interfaces.

[15]  F. Kang,et al.  Direct Growth of Carbon Nanotubes Doped with Single Atomic Fe–N4 Active Sites and Neighboring Graphitic Nitrogen for Efficient and Stable Oxygen Reduction Electrocatalysis , 2019, Advanced Functional Materials.

[16]  Yanghua He,et al.  3D porous graphitic nanocarbon for enhancing the performance and durability of Pt catalysts: a balance between graphitization and hierarchical porosity , 2019, Energy & Environmental Science.

[17]  D. Cullen,et al.  High-performance fuel cell cathodes exclusively containing atomically dispersed iron active sites , 2019, Energy & Environmental Science.

[18]  Chien-Lin Huang,et al.  Study of electrospun polyacrylonitrile fibers with porous and ultrafine nanofibril structures: Effect of stabilization treatment on the resulting carbonized structure , 2019, Journal of Applied Polymer Science.

[19]  M. Swihart,et al.  Achievements, challenges and perspectives on cathode catalysts in proton exchange membrane fuel cells for transportation , 2019, Nature Catalysis.

[20]  D. Papageorgopoulos,et al.  Platinum group metal-free catalysts boost cost competitiveness of fuel cell vehicles , 2019, Nature Catalysis.

[21]  Yanghua He,et al.  Metal-Nitrogen-Carbon Catalysts for Oxygen Reduction in PEM Fuel Cells: Self-Template Synthesis Approach to Enhancing Catalytic Activity and Stability , 2019, Electrochemical Energy Reviews.

[22]  Yanghua He,et al.  Atomically Dispersed Metal Catalysts for Oxygen Reduction , 2019, ACS Energy Letters.

[23]  Zhichuan J. Xu,et al.  In Situ X-ray Absorption Spectroscopy Studies of Nanoscale Electrocatalysts , 2019, Nano-micro letters.

[24]  Mehrez Agnaou,et al.  PoreSpy: A Python Toolkit for Quantitative Analysis of Porous Media Images , 2019, J. Open Source Softw..

[25]  Lirong Zheng,et al.  Fe–N–C electrocatalyst with dense active sites and efficient mass transport for high-performance proton exchange membrane fuel cells , 2019, Nature Catalysis.

[26]  Edward F. Holby,et al.  Progress in the Development of Fe‐Based PGM‐Free Electrocatalysts for the Oxygen Reduction Reaction , 2019, Advanced materials.

[27]  Yuyan Shao,et al.  PGM‐Free Cathode Catalysts for PEM Fuel Cells: A Mini‐Review on Stability Challenges , 2019, Advanced materials.

[28]  Yuyan Shao,et al.  Iron‐Free Cathode Catalysts for Proton‐Exchange‐Membrane Fuel Cells: Cobalt Catalysts and the Peroxide Mitigation Approach , 2019, Advanced materials.

[29]  A. Yu,et al.  Tailoring FeN4 Sites with Edge Enrichment for Boosted Oxygen Reduction Performance in Proton Exchange Membrane Fuel Cell , 2019, Advanced Energy Materials.

[30]  Evan C. Wegener,et al.  Highly active atomically dispersed CoN4 fuel cell cathode catalysts derived from surfactant-assisted MOFs: carbon-shell confinement strategy , 2019, Energy & Environmental Science.

[31]  Hyeon Seok Lee,et al.  Design Principle of Fe-N-C Electrocatalysts: How to Optimize Multimodal Porous Structures? , 2019, Journal of the American Chemical Society.

[32]  Ja-Yeon Choi,et al.  Integrating PGM‐Free Catalysts into Catalyst Layers and Proton Exchange Membrane Fuel Cell Devices , 2019, Advanced materials.

[33]  J. Qu,et al.  Non-precious nanostructured materials by electrospinning and their applications for oxygen reduction in polymer electrolyte membrane fuel cells , 2018, Journal of Power Sources.

[34]  D. Cullen,et al.  Atomically dispersed manganese catalysts for oxygen reduction in proton-exchange membrane fuel cells , 2018, Nature Catalysis.

[35]  Yi Jia,et al.  Defects on carbons for electrocatalytic oxygen reduction. , 2018, Chemical Society reviews.

[36]  Zheng Hu,et al.  Co nanoparticle embedded in atomically-dispersed Co-N-C nanofibers for oxygen reduction with high activity and remarkable durability , 2018, Nano Energy.

[37]  Tao Chen,et al.  A modular strategy for decorating isolated cobalt atoms into multichannel carbon matrix for electrocatalytic oxygen reduction , 2018 .

[38]  Shuhong Yu,et al.  Hierarchically structured Co3O4@carbon porous fibers derived from electrospun ZIF-67/PAN nanofibers as anodes for lithium ion batteries , 2018 .

[39]  R. Wycisk,et al.  Electrospun Fiber Mat Cathode with Platinum‐Group‐Metal‐Free Catalyst Powder and Nafion/PVDF Binder , 2018 .

[40]  L. Gu,et al.  ZIF-8/ZIF-67-Derived Co-Nx -Embedded 1D Porous Carbon Nanofibers with Graphitic Carbon-Encased Co Nanoparticles as an Efficient Bifunctional Electrocatalyst. , 2018, Small.

[41]  Yuyan Shao,et al.  Nitrogen‐Coordinated Single Cobalt Atom Catalysts for Oxygen Reduction in Proton Exchange Membrane Fuel Cells , 2018, Advanced materials.

[42]  Ke R. Yang,et al.  Active sites of copper-complex catalytic materials for electrochemical carbon dioxide reduction , 2018, Nature Communications.

[43]  Michael J. Workman,et al.  Role of Surface Chemistry on Catalyst/Ionomer Interactions for Transition Metal–Nitrogen–Carbon Electrocatalysts , 2017 .

[44]  Yuyan Shao,et al.  Single Atomic Iron Catalysts for Oxygen Reduction in Acidic Media: Particle Size Control and Thermal Activation. , 2017, Journal of the American Chemical Society.

[45]  X. Lou,et al.  Designed formation of hollow particle-based nitrogen-doped carbon nanofibers for high-performance supercapacitors , 2017 .

[46]  X. Bao,et al.  Surface functionalization of ZIF-8 with ammonium ferric citrate toward high exposure of Fe-N active sites for efficient oxygen and carbon dioxide electroreduction , 2017 .

[47]  Gangshan Wu,et al.  Role of Local Carbon Structure Surrounding FeN4 Sites in Boosting the Catalytic Activity for Oxygen Reduction , 2017 .

[48]  Dustin Banham,et al.  New insights into non-precious metal catalyst layer designs for proton exchange membrane fuel cells: Improving performance and stability , 2017 .

[49]  Hui Xu,et al.  Engineering Favorable Morphology and Structure of Fe-N-C Oxygen-Reduction Catalysts through Tuning of Nitrogen/Carbon Precursors. , 2017, ChemSusChem.

[50]  Lianjun Wang,et al.  Electrospun metal-organic framework derived hierarchical carbon nanofibers with high performance for supercapacitors. , 2017, Chemical communications.

[51]  Lianjun Wang,et al.  Electrospun ZIF-based hierarchical carbon fiber as an efficient electrocatalyst for the oxygen reduction reaction , 2017 .

[52]  Gang Wu,et al.  Engineering nanostructures of PGM-free oxygen-reduction catalysts using metal-organic frameworks , 2017 .

[53]  Shawn Litster,et al.  Resolving Electrode Morphology's Impact on Platinum Group Metal-Free Cathode Performance Using Nano-CT of 3D Hierarchical Pore and Ionomer Distribution. , 2016, ACS applied materials & interfaces.

[54]  Shiva Gupta,et al.  Carbon nanocomposite catalysts for oxygen reduction and evolution reactions: From nitrogen doping to transition-metal addition , 2016 .

[55]  A. Kucernak,et al.  In situ electrochemical quantification of active sites in Fe–N/C non-precious metal catalysts , 2016, Nature Communications.

[56]  J. Pampel,et al.  Opening of Bottleneck Pores for the Improvement of Nitrogen Doped Carbon Electrocatalysts , 2016 .

[57]  V. Ramani,et al.  Highly Active and Durable Non-Precious Metal Catalyst for the Oxygen Reduction Reaction in Acidic Medium , 2016 .

[58]  Yuanjian Zhang,et al.  Quantifying the density and utilization of active sites in non-precious metal oxygen electroreduction catalysts , 2015, Nature Communications.

[59]  S. Litster,et al.  In-Situ through-Plane Measurements of Ionic Potential Distributions in Non-Precious Metal Catalyst Electrode for PEFC , 2015 .

[60]  Lauren R. Grabstanowicz,et al.  Highly efficient nonprecious metal catalyst prepared with metal–organic framework in a continuous carbon nanofibrous network , 2015, Proceedings of the National Academy of Sciences.

[61]  K. Müllen,et al.  Mesoporous metal-nitrogen-doped carbon electrocatalysts for highly efficient oxygen reduction reaction. , 2013, Journal of the American Chemical Society.

[62]  Kyoungdoug Min,et al.  Experimental study on carbon corrosion of the gas diffusion layer in polymer electrolyte membrane fu , 2011 .

[63]  Kateryna Artyushkova,et al.  Synthesis-structure-performance correlation for polyaniline-Me-C non-precious metal cathode catalysts for oxygen reduction in fuel cells , 2011 .

[64]  Gang Wu,et al.  High-Performance Electrocatalysts for Oxygen Reduction Derived from Polyaniline, Iron, and Cobalt , 2011, Science.

[65]  Frédéric Jaouen,et al.  Iron-Based Catalysts with Improved Oxygen Reduction Activity in Polymer Electrolyte Fuel Cells , 2009, Science.

[66]  Frédéric Jaouen,et al.  Heat-treated Fe/N/C catalysts for O2 electroreduction: are active sites hosted in micropores? , 2006, The journal of physical chemistry. B.

[67]  S. Litster,et al.  PEM fuel cell electrodes , 2004 .