Cathode Catalysts For Fuel Cells Research Articles

Cu - Nitrogen doped graphene (Cu–N/Gr) nanocomposite as cathode catalyst in fuel cells – DFT study

Novel Cu-nitrogen doped graphene nanocomposite catalysts are developed to investigate the Cu-nitrogen doped fuel cell cathode catalyst. Density functional theory calculations are performed using Gaussian 09w software to study the oxygen reduction reaction (ORR) on Cu-nitrogen doped graphene nanocomposite cathode catalyst in low-temperature fuel cells. Three different nanocomposite structures Cu2–N6/Gr, Cu2–N8/Gr and Cu–N4/Gr were considered in the acidic medium under standard conditions (298.15 K, 1 atm) in order to explore the properties of the fuel cell. The results showed that all structures are stable at the potential range 0–5.87 V. Formation energy, Mulliken charge and HOMO-LUMO energy calculations showed that Cu2–N6/Gr and Cu2–N8/Gr are more stable structure-wise, while free energy calculations showed that only Cu2–N8/Gr and Cu–N4/Gr structures support spontaneous ORR. The maximum cell potential under standard conditions was shown at 0.28 V and 0.49 V for Cu2–N8/Gr and Cu–N4/Gr respectively. From the calculations, the Cu2–N6/Gr and Cu2–N8/Gr structures are less favorable in H2O2 generation; however, Cu–N4/Gr showed the potential for H2O2 generation. In conclusion, Cu2–N8/Gr and Cu–N4/Gr are more favorable to ORR than Cu2–N6/Gr.

Synthesized PdNi/C and PdNiZr/C catalysts for single cell PEM fuel cell cathode catalysts application

In this study, Vulcan XC-72 R supported PdNix, and PdNiZr bimetallic catalysts were synthesized by using sodium borohydride (NaBH4) and formic acid as reduction agents. The structural properties and morphological qualities of these nanocatalysts were evaluated by XRD, SEM, and TEM analysis. The XPS analysis spectra for Pd/C, PdNi/C, and PdNiZr/C catalysts showed that Pd, Ni, Zr, and C elements successfully entered the structure. The weights in percent metals of the Pd/C, PdNi/C, and PdNiZr/C catalysts were determined by EDX analysis. In addition, these catalysts' electrochemical properties, activity, and stability, such as their electrochemically active surface area (ESA), were examined using cyclic voltammetry (CV) chronoamperometry, chronopotentiometry, and electrochemical impedance spectroscopy. Polarization curves were created for Pd/C, PdNi/C, and PdNiZr/C catalysts utilized as cathode electrocatalysts in a single cell at temperatures of 40 °C, 50 °C, 60 °C, and 70 °C. The PdNiZr/C and PdNi/C catalysts were determined to have higher performance than the Pd/C catalyst. Power densities of Pd/C, PdNi/C, and PdNiZr/C catalysts were measured to be 27.54 mWcm−2, 114 mWcm−2, and 188 mWcm−2, at 70 °C, respectively.

Atomically Dispersed Zn‐Pyrrolic‐N4 Cathode Catalysts for Hydrogen Fuel Cells

AbstractTo achieve practical application of fuel cell, it is vital to develop highly efficient and durable Pt‐free catalysts. Herein, we prepare atomically dispersed ZnNC catalysts with Zn‐Pyrrolic‐N4 moieties and abundant mesoporous structure. The ZnNC‐based anion‐exchange membrane fuel cell (AEMFC) presents an ultrahigh peak power density of 1.63 and 0.83 W cm−2 in H2‐O2 and H2‐air (CO2‐free), and also exhibits long‐term stability with more than 120 and 100 h for H2‐air (CO2‐free) and H2‐O2, respectively. Density functional calculations further unveil that the Zn‐Pyrrolic‐N4 structure is the origin of high activity of as‐synthesized ZnNC catalyst, while the Zn‐Pyridinic‐N4 moiety is inactive for oxygen reduction reaction (ORR), which successfully explain the puzzle why most Zn‐metal‐organic framework ‐derived ZnNC catalysts in previous reports did not present good ORR activity because of their Zn‐Pyridinic‐N4 moieties. This work offers a new route for speeding up development of AEMFCs.

Atomically Dispersed Zn-Pyrrolic-N4 Cathode Catalysts for Hydrogen Fuel Cells.

To achieve practical application of fuel cell, it is vital to develop highly efficient and durable Pt-free catalysts. Herein, we prepare atomically dispersed ZnNC catalysts with Zn-Pyrrolic-N4 moieties and abundant mesoporous structure. The ZnNC-based anion-exchange membrane fuel cell (AEMFC) presents an ultrahigh peak power density of 1.63 and 0.83 W cm-2 in H2 -O2 and H2 -air (CO2 -free), and also exhibits long-term stability with more than 120 and 100 h for H2 -air (CO2 -free) and H2 -O2 , respectively. Density functional calculations further unveil that the Zn-Pyrrolic-N4 structure is the origin of high activity of as-synthesized ZnNC catalyst, while the Zn-Pyridinic-N4 moiety is inactive for oxygen reduction reaction (ORR), which successfully explain the puzzle why most Zn-metal-organic framework -derived ZnNC catalysts in previous reports did not present good ORR activity because of their Zn-Pyridinic-N4 moieties. This work offers a new route for speeding up development of AEMFCs.

Benchmarking proton exchange membrane fuel cell cathode catalyst at high current density: A comparison between the rotating disk electrode, the gas diffusion electrode and differential cell

The intrinsic activity of oxygen reduction reaction (ORR) electrocatalysts for proton exchange membrane fuel cell (PEMFC) is usually evaluated with the rotating disk electrode (RDE), an easy-to-use technique requiring little amount of electrocatalyst. However, the liquid environment of the RDE implies strong limitation of O2 mass-transport and the intrinsic activity is only accessible on a narrow potential range (from 0.95 to 0.85 V vs. RHE) that is not relevant for the PEMFC operating conditions. This work compares results obtained with the RDE (0.2 cm2), the gas diffusion electrode (GDE, 0.07 cm2) and a small unit PEMFC (DC, 1.8 cm2). Three widely used ORR electrocatalysts are compared: Pt/Vulcan carbon, PtCo/Vulcan carbon and Pt/graphitized carbon, catalytic layers being prepared with a loading of 20 μgPt cm−2 and characterized at 25–30 °C and full hydration. The results show that all setups have their own advantages and drawbacks. Regardless the electrocatalyst nature, the GDE allows to assess the intrinsic activities on a large potential range (from 0.9 to 0.6 V), in agreement with the results obtained in RDE for high potential and with the DC for lower potential. The GDE is therefore promising, enabling easy high current density measurements with little amount of electrocatalyst.

Ordered CoPt oxygen reduction catalyst with high performance and durability

A high-performance and durable polymer electrolyte membrane fuel cell cathode catalyst composed of an ordered L1 0 –CoPt core and a thin Pt shell was designed and prepared. Under practical fuel cell membrane electrode assembly testing conditions, the cathode catalyst showed an outstanding initial mass activity of 0.6 A/mg Pt , which satisfies the U.S. Department of Energy performance target while also meeting the durability target of less than 40% loss in mass activity after 30,000 accelerated stress test voltage cycles. The high structural stability of the L1 0 –CoPt@Pt-shell catalyst was confirmed by postmortem materials characterization, and the origin of this robustness was revealed by density functional theory calculations, where the barriers for diffusion of Co atoms were observed to be significantly increased in the ordered intermetallic core. • An intermetallic ORR catalyst was prepared through a scalable impregnation method • Mass activity of 0.6 A/mg Pt and high durability were achieved in fuel cell testing • H 2 /air power density of 0.87 W/cm 2 at 0.67 V was achieved with only 0.1 mgPt/cm 2 • Order-dependent energetics of vacancy-mediated diffusion were evaluated using DFT Fuel cells with high power density and high durability could contribute to the realization of net zero carbon emissions in the transportation sector. The catalyst reported here, which uses atomic-level ordering to stabilize Co within the intermetallic CoPt lattice, achieves higher Co retention and better durability compared with conventional CoPt catalysts. The origins of this high durability were investigated using density functional theory calculations, which revealed significantly higher barriers for Co diffusion in ordered catalysts compared with disordered ones. This new intermetallic catalyst is a promising candidate for deployment in transportation and other clean-energy fuel cell applications. An oxygen reduction reaction catalyst composed of core-shell CoPt nanoparticles possessing an ordered Co–Pt core and Pt shell shows excellent performance and durability in fuel cell testing.

Iron and tin phosphide as polymer electrolyte membrane fuel cell cathode catalysts

A new set of catalysts based on metal-phosphorus/nitrogen-carbon, for the electroreduction of molecular oxygen at the polymer electrolyte membrane fuel cell cathode are reported. These catalysts were simply made from folic acid, phosphoric acid, iron or tin oxides. In particular, the tin oxide-based catalyst exhibited superior electrocatalytic activity against state-of-the-art non-platinum-based catalysts with a mass activity of 6 mA mg−1. Successful application of these catalysts at the cathode of a self-breathing fuel cell is also demonstrated, and this validated the suitability of the catalyst to operate under fuel cell conditions. A power density of 12.6 mW cm−2 at ambient condition (25 °C, 20% relative humidity and dry hydrogen) was achieved. This work provides foundation for the emergence of phosphorous based non-platinum catalysts for fuel cell cathodes.

Quantitative Analysis of Fuel Cell Cathode Catalyst Layer Degradation Using Scanning Transmission Electron Microscopy and Energy Dispersive Spectroscopy

Proton exchange membrane fuel cells (PEMFCs) are a central technology for the electrification of the heavy-duty automotive fleet, ultimately enabling reduced carbon emissions. However, improvements in lifetime and cost are necessary before mass adoption of PEMFC vehicles is achieved. Significant research into analyzing and mitigating degradation of catalyst layers (CLs) is ongoing and this work highlights a transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) approach aimed at quantifying electrochemically active surface area (ECSA) loss through the thickness of CLs resulting from electrochemical-applied, catalyst-specific accelerated stress tests or ASTs.Several mechanisms contribute to degradation of the catalysts in PEMFCs, including Ostwald ripening, coalescence, and formation of a Pt band within the membrane, which result in decreased active surface area throughout the CL. TEM has often been used in conjunction with electrochemical testing to infer changes in the catalyst nanoparticle size, distribution, and changes to the support materials within the catalyst layer (CL) to investigate catalyst. Typically, high-magnification TEM with high-resolution are used to infer localized changes within the CL by examining shape and size to provide information concerning the degradation mechanism. Low-magnification TEM is typically used to observe changes in the support, ionomer, and catalyst distribution. Here we use a quantitative approach to show elemental differences within the CL by using scanning transmission electron microscopy and energy dispersive spectroscopy maps (STEM/EDS) for a given MEA that underwent catalyst-specific ASTs. This approach uses the fluorine to platinum ratio (F/Pt) from a fresh sample as a benchmark to track loss of Pt through the thickness of the CL of aged samples. This information can then be used to compare differences in various locations on the MEA in relationship to gas inlets and outlets as well as changes induced by different stressors during the catalyst ASTs. This analysis complements studies using bulk techniques, such as electrochemical ECSA via cyclic voltammetry and micro-X-ray diffraction (µ-XRD), to confirm trends in CL degradation.

Understanding the Electrochemical Dissolution of Polymer Electrolyte Fuel Cell Cathode Catalysts for Heavy Duty Applications Using Online ICP-MS

Fuel cells for heavy-duty vehicles (HDVs) have attracted considerable attention because of their unique scalability, better fuel economy, and less demand for hydrogen refilling infrastructure relative to the light-duty vehicle application.1 However, the HDV application requires more stringent fuel cell durability, up to 25,000 h or 1 million miles of operation and increased efficiency. 1-2 Cathodes with relatively high Pt loading (~0.3 mg-Pt/cm2) have drawn extensive attention over initially highly active but unstable Pt-transition metal (Pt-TM) alloy3 catalysts owing to their capability of delivering high performance over long HDV lifetime. To fully exploit the potential of Pt in the HDV cathodes, new insights into the relationship between different drive cycles and operating conditions of HDVs and durability are needed with a particular emphasis on understanding the mechanisms for dissolution of Pt. Several mechanisms for dissolution of platinum have been proposed including direct Pt dissolution and electrochemical oxidation of the Pt surface atoms followed by chemical dissolution of the resulting Pt surface oxide. This presentation will outline the dissolution of Pt under various operating conditions in an electrochemical flow cell system connected to an inductively-coupled plasma-mass spectrometer (ICP-MS) capable of detecting trace concentrations (<ppb) of dissolved elements in solution. The electrochemical data combined with the ICP-MS data are used to evaluate the influence of various factors such as potential, potentiodynamic profile parameters (e.g., scan rate, upper and lower potential limits), Pt catalyst particle size, and support type on the dissolution processes in acidic electrolytes at room and elevated temperatures. AcknowledgementsThis work was supported by the U.S. Department of Energy, Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office (HFTO) through the Million Mile Fuel Cell Truck (M2FCT) Consortium. Argonne National Laboratory is managed for the U.S Department of Energy by the University of Chicago Argonne, LLC, also under contract DE-AC-02-06CH11357. References A. Cullen, K. C. Neyerlin, R. K. Ahluwalia, R. Mukundan, K. L. More, R. L. Borup, A. Z. Weber, D. J. Myers, and A. Kusoglu, Nat. Energy, 6, 462 (2021).Marcinkoski, et al. Hydrogen Class 8 Long Haul Truck Targets (US Department of Energy, 2019);https://www.hydrogen.energy.gov/pdfs/19006_hydrogen_class8_long_haul_truck_targets.pdfL. Borup, et al., Curr. Opin. Electrochem. 21, 192–200 (2020).

Mitigating Pt Loss in Polymer Electrolyte Membrane Fuel Cell Cathode Catalysts Using Graphene Nanoplatelet Pickering Emulsion Processing

AbstractCarbon‐supported Pt nanoparticles are the leading catalysts for the cathode oxygen reduction reaction (ORR) in polymer electrolyte membrane fuel cells. However, these ORR catalysts suffer from poor electrochemical durability, particularly the loss of electrochemical surface area (ECSA) due to Pt nanoparticle dissolution and agglomeration. Here, Pt loss is mitigated through a Pickering emulsion‐processing strategy that employs graphene nanoplatelet dispersions stabilized by the polymer ethyl cellulose. The resulting graphene‐Pt/Vulcan carbon (Pt/C) catalysts exhibit superior durability and ECSA retention throughout an accelerated stress test compared with a commercial Pt/C standard catalyst, both in a diagnostic‐rotating disc electrode setup and in a membrane electrode assembly full cell. These graphene‐Pt/C catalysts also improve durability at high‐voltage conditions, providing further evidence of their exceptional electrochemical stability. Consistent with density functional theory calculations, postelectrochemical characterization reveals that Pt nanoparticles localize at graphene defects both on the basal plane and especially at the edges of the graphene nanoplatelets. Since this Pt nanoparticle localization suppresses Pt nanoparticle dissolution and agglomeration without hindering accessibility of the reactant species to the catalyst surface, the ORR performance under both idealized and practical experimental conditions shows significantly improved durability while maintaining high electrochemical activity.

Transition Metal and Nitrogen-Doped Mesoporous Carbons As Cathode Catalysts for Anion-Exchange Membrane Fuel Cells

Energy is an essential part of our lives and causes significant impact on the environment. As hydrogen is clean, cost-efficient and easily producible, then it is believed to become an essential player in the energy field.1 The proton exchange membrane fuel cells fueled by hydrogen are already used in the transport sector, but their further commercialization is limited by the excess usage of precious metals. To ease the search for replacements, the harsh acidic environment can be changed to alkaline, thus giving opportunity to use non-precious metal catalysts.2 Especially for the cathodic oxygen reduction reaction (ORR), different transition metal-containing nitrogen-doped carbon-based materials have shown great promise.3 This gives an opportunity for the rise of anion exchange membrane fuel cells (AEMFCs) as future hydrogen-based energy devices.2,3 In this work, a novel catalyst support based on mesoporous carbon (MPC, from Pajarito Powder, LLC) is used to produce M−N−C type catalyst materials. Such mesoporous structure is useful for better mass transport in the catalyst layer during AEMFC operation. This MPC support is mixed with 1,10-phenanthroline as nitrogen source and transition metal acetates, followed by high-temperature pyrolysis at 800 °C in an inert atmosphere. Five M-N-C materials are prepared with the following transition metal combinations: Co, Fe, CoFe, CoMn, and FeMn.Several physico-chemical characterization methods (SEM-EDX, STEM, XPS, MP-AES, Raman spectroscopy, and N2 physisorption) are employed to study the materials. These indeed proved that all five catalyst materials have feasible mesoporous structure (pore diameters predominantly 7-8 and 25-35 nm) and the doping with transition metals (content ca. 1 wt%) and nitrogen (ca. 2.3 at%) has been a success. The electrochemical testing to study the ORR pathway and activity of these materials in alkaline media was done using the RRDE method. CoFe-N-MPC, Fe-N-MPC and FeMn-N-MPC catalysts showed similar and excellent electrocatalytic performance by obtaining half-wave potential of 0.9 V vs RHE. The lowest peroxide yield was obtained with Fe-N-MPC and FeMn-N-MPC. The latter two catalyst materials also showed very good performance as cathode catalysts in an H2/O2 AEMFC together with an HMT-PMBI4 membrane, obtaining peak power density of >470 mW cm–2. This indicates that the M-N-MPC materials are promising cathode catalysts for the AEMFC application.References Nazir, H.; Louis, C.; Jose, S.; Prakash, J.; Muthuswamy, N.; Buan, M.E.M.; Flox, C.; Chavan, S.; Shi, X.; Kauranen, P.; Kallio, T.; Maia, G.: Tammeveski, K.; Lymperopoulos, N.; Carcadea, E.; Veziroglu, E.; Iranzo, A.; Kannan, A.M. Is the H2 economy realizable in the foreseeable future? Part I: H2 production methods. J. Hydrogen Energy 2020, 45, 13777-13788, DOI: 10.1016/j.ijhydene.2020.03.092Gottesfeld, S.; Dekel, D. R.; Page, M.; Bae, C.; Yan, Y. S.; Zelenay, P.; Kim, Y. S. Anion exchange membrane fuel cells: current status and remaining challenges. Power Sources 2018, 375, 170-184, DOI: 10.1016/j.jpowsour.2017.08.010Sarapuu, A.; Kibena-Põldsepp, E.; Borghei, M.; Tammeveski, K. Electrocatalysis of oxygen reduction on heteroatom-doped nanocarbons and transition metal–nitrogen–carbon catalysts for alkaline membrane fuel cells. J. Mater. Chem. A 2018, 6, 776-804, DOI: 10.1039/C7TA08690C.Wright, A.G.; Fan, J.T.; Britton, B.; Weissbach, T.; Lee, H.F.; Kitching, E.A.; Peckham, T.J.; Holdcroft, S. Hexamethyl-p-terphenyl poly(benzimidazolium): a universal hydroxide-conducting polymer for energy conversion devices. Energy Environ. Sci., 2016, 9, 2130-2142, DOI: 10.1039/C6EE00656F.

Methods— A Simple Method to Measure In-Plane Electrical Resistance of PEM Fuel Cell and Electrolyzer Catalyst Layers

Optimizing the catalyst layer of polymer electrolyte membrane fuel cells and water electrolyzers requires a good understanding of its properties. The in-plane electrical resistance of the catalyst layer is a key property, which impacts the overall cell performance. In this work, we present a simple method to measure the in-plane electrical resistance of catalyst layers under various conditions based on the transfer length method. The applicability of the method was demonstrated on four examples: 1) Placing the compact setup in a climate chamber, showed that reducing the relative humidity from 95% to 40% yields a reduction of the resistivity of 15% in a fuel cell cathode catalyst layer; 2) graphitizing CNovel™ carbon support reduces the resistivity by 98% in a fuel cell cathode catalyst layer; 3) adding an electrically conductive polymer as electrode binder lowers the in-plane resistivity of a water electrolyzer anode by 50%; 4) adding IrO2-nanofibers to a low-loaded IrO2-nanoparticle anode lowers its resistivity by 60%. The broad range of applications in this work confirms the versatility of the setup enabling widespread application. The method hence contributes to an improved deconvolution of different loss mechanisms including electrical in-plane resistivity.

Ordered mesoporous carbon supported fuel cell cathode catalyst for improved oxygen transport

In this study, ordered mesoporous carbon (OMC or CMK-3) was evaluated as a viable carbon support in place of widely used high surface area (HSC or Ketjenblack® EC-300J) and Vulcan supports. The OMC carbon has significant mesoporous (pore diameter from 2 to 5 nm) volume in an ordered fashion thereby enabling improved access of Pt sites to O2 transport. The measured local oxygen transport resistance (R(O2)-local) of Pt supported OMC was quite low (3 s/cm) compared to that of HSC (15.9 s/cm) and Vulcan (8.3 s/cm). Also, Pt/OMC exhibited better beginning of life (BOL) fuel cell performance under H2-Air at 80 °C compared to that of Pt/V and Pt/HSC at high current densities (>1.5 A/cm2). Finally, voltage cycling measurements (30,000 cycles) were done to measure the durability of the electrocatalysts. Both Pt/HSC and Pt/OMC showed comparable fuel cell performance at end of test (EOT) especially at high current densities. In summary, our physical and electrochemical study of Pt/OMC suggest that it could be a potential replacement to the widely used HSC and Vulcan carbon supports.

Design and optimization of gradient wettability pore structure of adaptive PEM fuel cell cathode catalyst layer

The design of cathode catalyst layer (CL) is essential to improve the mass transfer capacity of proton exchange membrane (PEM) fuel cell and increase power density. In this work, cathode CL is divided into three sub-layers, and each sub-layer is added nano-particles with different wettability. The gradient CL with hydrophilic SiO2 particles at inner layer and hydrophobic polytetrafluoroethylene (PTFE) particles at outer layer significantly enhances the performance of membrane exchange assembly (MEA). Its performance is 895 mW/cm2@0.6 V, which is 24.1 %higher than CL without any particles (721 mW/cm2@ 0.6 V). Under operating conditions of high current density, high cathode humidity and high air stoichiometry, the gradient CL has only a little voltage loss. Through Electrochemical Impedance Spectroscopies (EIS) impedance analysis under high current density (1.8A/cm2), mass transfer resistance of gradient CL is 25.4 Ω, and is much smaller than the mass transfer resistance of the homogeneous CL of 35.1 Ω, which reflects the significant enhancement in mass transfer capacity of gradient CL. The gradient catalyst layer is suitable for a wider range of current density, humidity, and stoichiometry, but excessive cathode gas stoichiometry causes a decrease in performance, which is caused by excessive drainage capacity. In addition, 18 different gradient CLs are designed and manufactured, and the gradient CL with catalyst coated membrane (CCM) structure has the best performance. In gradient CL, increasing the capillary pressure difference between sublayers is the key to performance improvement. It is confirmed that the property of MEA with appropriate wettability gradient design can be significantly improved.

Quantification on degradation mechanisms of polymer exchange membrane fuel cell cathode catalyst layers during bus and stationary durability test protocols

Simulating bus and stationary protocols are designed to study the durability and degradation mechanisms of proton exchange membrane fuel cells. A quantitative method combined with characterization techniques, including electrochemical impedance spectroscopy, X-ray fluorescence spectroscopy and X-ray diffraction spectroscopy, is applied to distinguish performance degradation. Experimental results show that, for proton exchange membrane attenuation, chemical attenuation due to high cathode potential with long duration is more severe than mechanism attenuation due to dynamic load. For cathode catalyst layer decay, the principal reason under bus condition is particles growth (∼35%), followed by Pt dissolution (∼34%). In contrast,∼43% ECSA loss results from ionomer/catalyst interface loss under stationary condition. Such information indicates that the bus condition results in particles growth and Pt dissolution while the stationary condition induces ionomer/catalyst interface loss in the cathode catalyst layer. Combining more realistic protocols and quantitative analysis method can reveal the relationship between operating conditions of fuel cell in realistic road and MEA degradation. • Simulating stationary and bus protocols are used to study MEA degradation. • The attenuation mechanisms of MEA under these two protocols is proposed. • Chemical decay by durable high-potential affects severely PEM durability. • Particle growth and Pt dissolution cease CL decay under bus protocol. • Ionomer loss ceases CL degradation under stationary protocol.

Property-reactivity relations of N-doped PEM fuel cell cathode catalyst supports

This study clarifies the effect of the nature of solid N-precursor molecules on the N-modification, more specifically unravels how solid N-precursors – here cyanamide and melamine - affect the physicochemical and catalytic properties of the resulting carbonsupports and final catalysts. Using such modified high surface area carbons, in situ measurements as humidity dependent performance, electrochemical surface area, proton resistivity and limiting current measurements were conducted to access the role and degree of ionomer coverage and transport resistances. Additional X-ray photoelectron spectroscopy (XPS) proves molecular interaction between acidic side chains and basic N-groups. Overall, we show the importance of the N-precursor and synthetic route determining which physicochemical parameter will be influenced in the resulting catalytic layer. Based on this, the pure presence of some N-moieties does not guarantee an improved ionomer distribution, but the modification process enables a tailoring effect of the carbon species itself affecting transport phenomena.

Cobalt-Doped Carbon Nanofibers as Cathode Catalyst for Fuel Cell

Cobalt-Doped Carbon Nanofibers as Cathode Catalyst for Fuel Cell

Ws2/Ceo2 Composite as an Efficient Cathode Catalyst in a Dual-Chamber Microbial Fuel Cell

Ws2/Ceo2 Composite as an Efficient Cathode Catalyst in a Dual-Chamber Microbial Fuel Cell

Iron and Nickel Phthalocyanine-Modified Nanocarbon Materials as Cathode Catalysts for Anion-Exchange Membrane Fuel Cells and Zinc-Air Batteries

Iron and Nickel Phthalocyanine-Modified Nanocarbon Materials as Cathode Catalysts for Anion-Exchange Membrane Fuel Cells and Zinc-Air Batteries

Iron and Nickel Phthalocyanine-Modified Nanocarbon Materials as Cathode Catalysts for Anion-Exchange Membrane Fuel Cells and Zinc-Air Batteries

Iron and Nickel Phthalocyanine-Modified Nanocarbon Materials as Cathode Catalysts for Anion-Exchange Membrane Fuel Cells and Zinc-Air Batteries