The prohibitive cost of platinum for catalyzing the cathodic oxygen reduction reaction (ORR) has hampered the widespread use of polymer electrolyte fuel cells. We describe a family of non-precious metal catalysts that approach the performance of platinum-based systems at a cost sustainable for high-power fuel cell applications, possibly including automotive power. The approach uses polyaniline as a precursor to a carbon-nitrogen template for high-temperature synthesis of catalysts incorporating iron and cobalt. The most active materials in the group catalyze the ORR at potentials within ~60 millivolts of that delivered by state-of-the-art carbon-supported platinum, combining their high activity with remarkable performance stability for non-precious metal catalysts (700 hours at a fuel cell voltage of 0.4 volts) as well as excellent four-electron selectivity (hydrogen peroxide yield <1.0%).

/pdf/high-performance-electrocatalysts-for-oxygen-reduction-3w5qtsq9yn.pdf

High-Performance Electrocatalysts for Oxygen Reduction Derived from Polyaniline, Iron, and Cobalt

Fuel cell catalysts synthesized from abundant metals approach the performance and durability of platinum at lower cost. The prohibitive cost of platinum for catalyzing the cathodic oxygen reduction reaction (ORR) has hampered the widespread use of polymer electrolyte fuel cells. We describe a family of non–precious metal catalysts that approach the performance of platinum-based systems at a cost sustainable for high-power fuel cell applications, possibly including automotive power. The approach uses polyaniline as a precursor to a carbon-nitrogen template for high-temperature synthesis of catalysts incorporating iron and cobalt. The most active materials in the group catalyze the ORR at potentials within ~60 millivolts of that delivered by state-of-the-art carbon-supported platinum, combining their high activity with remarkable performance stability for non–precious metal catalysts (700 hours at a fuel cell voltage of 0.4 volts) as well as excellent four-electron selectivity (hydrogen peroxide yield <1.0%).

The recent advances in electrocatalysis for oxygen reduction reaction (ORR) for proton exchange membrane fuel cells (PEMFCs) are thoroughly reviewed. This comprehensive Review focuses on the low- and non-platinum electrocatalysts including advanced platinum alloys, core–shell structures, palladium-based catalysts, metal oxides and chalcogenides, carbon-based non-noble metal catalysts, and metal-free catalysts. The recent development of ORR electrocatalysts with novel structures and compositions is highlighted. The understandings of the correlation between the activity and the shape, size, composition, and synthesis method are summarized. For the carbon-based materials, their performance and stability in fuel cells and comparisons with those of platinum are documented. The research directions as well as perspectives on the further development of more active and less expensive electrocatalysts are provided.

http://repository.ust.hk/ir/bitstream/1783.1-77094/1/acs.chemrev.5b00462_withlink.pdf

Recent Advances in Electrocatalysts for Oxygen Reduction Reaction

Because of the remarkably high theoretical energy output, metal–air batteries represent one class of promising power sources for applications in next-generation electronics, electrified transportation and energy storage of smart grids. The most prominent feature of a metal–air battery is the combination of a metal anode with high energy density and an air electrode with open structure to draw cathode active materials (i.e., oxygen) from air. In this critical review, we present the fundamentals and recent advances related to the fields of metal–air batteries, with a focus on the electrochemistry and materials chemistry of air electrodes. The battery electrochemistry and catalytic mechanism of oxygen reduction reactions are discussed on the basis of aqueous and organic electrolytes. Four groups of extensively studied catalysts for the cathode oxygen reduction/evolution are selectively surveyed from materials chemistry to electrode properties and battery application: Pt and Pt-based alloys (e.g., PtAu nanoparticles), carbonaceous materials (e.g., graphene nanosheets), transition-metal oxides (e.g., Mn-based spinels and perovskites), and inorganic–organic composites (e.g., metal macrocycle derivatives). The design and optimization of air-electrode structure are also outlined. Furthermore, remarks on the challenges and perspectives of research directions are proposed for further development of metal–air batteries (219 references).

Metal–air batteries: from oxygen reduction electrochemistry to cathode catalysts

Developing highly efficient catalysts for the oxygen reduction reaction (ORR) is key to the fabrication of commercially viable fuel cell devices and metal–air batteries for future energy applications. Herein, we review the most recent advances in the development of Pt-based and Pt-free materials in the field of fuel cell ORR catalysis. This review covers catalyst material selection, design, synthesis, and characterization, as well as the theoretical understanding of the catalysis process and mechanisms. The integration of these catalysts into fuel cell operations and the resulting performance/durability are also discussed. Finally, we provide insights into the remaining challenges and directions for future perspectives and research.

Recent advancements in Pt and Pt-free catalysts for oxygen reduction reaction

Electrochemical energy conversion technologies based on the oxygen evolution reaction (OER) are at the heart of many efforts to achieve a sustainable future, carbon-free fuel, and a circular economy. The sluggish kinetics of oxygen electrocatalysis, as well as the high overpotential required to attain practical current densities, limit the efficiency of several promising electrochemical technologies, including water and carbon dioxide electrolyzers, metal–oxygen batteries, and fuel cells. The most efficient OER catalysts are precious metals such as iridium- and ruthenium-based materials (i.e., IrO2 and RuO2). This fact represents a challenge against the cost-effective implementation of these electrolysis technologies.1-3 As a result, there is a necessity for the development of cost effective PGM-free OER catalysts, with equivalent or superior activity and durability to the PGM catalysts.
 This presentation will discuss the development and implementation of high-throughput synthesis methodology for PGM-free OER catalysts exploiting the rich chemistry of nanoporous materials4-7 and Argonne National Laboratory's High-Throughput Research Facility. The developed high-throughput methodology will expedite the assessment of the effect of composition and synthesis parameters on the activity of perovskite oxide alkaline electrolyte OER catalysts.
 Acknowledgements
 This work was supported by the U.S. Department of Energy, Advanced Research Projects Agency Energy (ARPA-E) under the DIFFERENTIATE program. This work was authored in part by Argonne National Laboratory, a U.S. Department of Energy (DOE) Office of Science laboratory operated for DOE by UChicago Argonne, LLC under contract no. DE-AC02-06CH11357.
 References 
 
 Katsounaros, Ioannis, Serhiy Cherevko, Aleksandar R. Zeradjanin, and Karl JJ Mayrhofer. "Oxygen electrochemistry as a cornerstone for sustainable energy conversion." Angewandte Chemie International Edition53, no. 1 (2014): 102-121.
 
 
 Lee, Youngmin, Jin Suntivich, Kevin J. May, Erin E. Perry, and Yang Shao-Horn. "Synthesis and activities of rutile IrO2 and RuO2 nanoparticles for oxygen evolution in acid and alkaline solutions." The journal of physical chemistry letters3, no. 3 (2012): 399-404.
 
 
 Cherevko, S. et al. Oxygen and hydrogen evolution reactions on Ru, RuO2, Ir, and IrO2 thin film electrodes in acidic and alkaline electrolytes: A comparative study on activity and stability. Today
 262, 170–180 (2016).
 
 
 Nahar, Lamia, Ahmed A. Farghaly, Richard J. Alan Esteves, and Indika U. Arachchige. "Shape controlled synthesis of Au/Ag/Pd nanoalloys and their oxidation-induced self-assembly into electrocatalytically active aerogel monoliths." Chemistry of Materials29, no. 18 (2017): 7704-7715.
 
 
 Farghaly, Ahmed A., Rezaul K. Khan, and Maryanne M. Collinson. "Biofouling-resistant platinum bimetallic alloys." ACS applied materials & interfaces10, no. 25 (2018): 21103-21112.
 
 
 Khan, Rezaul K., Ahmed A. Farghaly, Tiago A. Silva, Dexian Ye, and Maryanne M. Collinson. "Gold-Nanoparticle-Decorated Titanium Nitride Electrodes Prepared by Glancing-Angle Deposition for Sensing Applications." ACS Applied Nano Materials2, no. 3 (2019): 1562-1569.
 
 
 Farghaly, Ahmed A., Mai Lam, Christopher J. Freeman, Badharinadh Uppalapati, and Maryanne M. Collinson. "Potentiometric measurements in biofouling solutions: comparison of nanoporous gold to planar gold." Journal of The Electrochemical Society 163, no. 4 (2015): H3083.
 
 


High Throughput Synthesis of Perovskite Oxides for Alkaline Oxygen Evolution Reaction Electrocatalysis: Nature of the a and B Sites

The highest oxygen reduction reaction (ORR) activities in acidic environments for platinum group metal-free electrocatalysts have been achieved for materials derived from iron, nitrogen, and carbon-containing precursors such as iron-substituted zinc-based zeolitic imidazolate frameworks (ZIF).[1-3] These precursors are typically heat treated in an inert atmosphere at temperatures ranging from 900 to 1100°C to form the ORR-active material. In addition to their high intrinsic activity, under certain preparation conditions these catalysts are free of crystalline iron species, with iron atomically dispersed in a nitrogen-doped carbon matrix, as determined through characterization by high-resolution electron microscopy and X-ray absorption spectroscopy. While the exact nature of the active site in these materials is still a matter of debate, the probe molecule, nitric oxide, has been shown to bind to Fe, using nuclear resonance vibrational spectroscopy, and also to poison the ORR.[4-6] An in-depth study of the interaction of nitric oxide with a variety of Fe-N-C catalysts can thus provide insight into the nature of the ORR active site in this class of catalysts. This presentation will discuss the application of multiple characterization techniques to understand the interaction of nitric oxide with Fe-N-C catalysts, including nuclear resonance vibrational spectroscopy, temperature-programmed desorption, and in situ X-ray absorption spectroscopy as a function of potential in aqueous acidic electrolyte. The implications of the results of these studies on the nature of the ORR active site will be discussed.
 References
 1. X.X. Wang, M.T. Swihart, and G. Wu, “Achievements, challenges, and perspectives on cathode catalysts in proton exchange membrane fuel cells for transportation”, Nature Catalysis, 2 (2019) 578-589.
 2. M. Chen, Y. He, J.S. Spendelow, and G. Wu, ACS Energy Letters, 4 (2019) 1619-1633.
 3. S.T. Thompson and D. Papageorgopoulos, Nature Catalysis, 2 (2019) 558-561.
 4. J.L. Kneebone, et al., “A Combined Probe-Molecule, Mossbauer, Nuclear Resonance Vibrational Spectroscopy, and Density Functional Theory Approach for Evaluation of Potential Iron Active Sites in an Oxygen Reduction Reaction Catalyst”, J. Phys. Chem. C 121 (2017) 16283-16290.
 5. D. Myers and P. Zelenay, “ElectroCat (Electrocatalysis Consortium)”, Department of Energy Hydrogen and Fuel Cells Program Annual Merit Review, 2019. https://www.hydrogen.energy.gov/pdfs/review19/fc160_myers_zelenay_2019_o.pdf
 6. P. Boldrin, et al., “Deactivation, reactivation and super-activation of Fe-N/C oxygen reduction electrocatalysts: Gas sorption, physical and electrochemical investigation using NO and O2”, Appl. Cat. B: Environ., 292 (2021) 120169-120180.
 Acknowledgements
 This work was supported by the U.S. Department of Energy, Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office under the auspices of the Electrocatalysis Consortium (ElectroCat 2.0). This research used the resources of the Advanced Photon Source (APS), a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. 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.

Nitric Oxide Probe Molecule Studies of Iron-Nitrogen-Carbon PEMFC Oxygen Reduction Reaction Electrocatalysts

The sluggish kinetics of oxygen electrocatalysis and the resulting high overpotentials necessary to achieve useful current densities limit the development of promising technologies, such as fuel cells, water, and carbon dioxide electrolyzers, and metal-oxygen batteries.1 The best catalysts for both the oxygen reduction and oxygen evolution reactions (ORR and OER, respectively) are based on precious, platinum group metals (PGMs), such as platinum and iridium, leading to limitations in the cost-effective implementation of these technologies.2,3 The development of alternative catalysts, with comparable or higher activity and durability to the PGM catalysts and derived from earth-abundant materials has thus been an active research area for decades.
 Incredible progress has been made in developing PGM-free electrocatalysts for the OER in alkaline environments, with perovskite oxides showing activities comparable to PGM-based catalysts.4,5 Perovskite oxides are a very broad class of materials with the general formula of ABO3, where the B site is occupied by smaller transition metal ions and the A site by larger cations which have 12-fold coordination with O.4 Both the A sites and B sites can be occupied by multiple metal ions, leading to an even more expansive design space for this class of materials. Another interesting class of catalysts is Fe and Ni oxides derived from the electrochemical oxidation of metal-organic frameworks (MOFs), with the advantages of this material over the perovskites being high electronic conductivity and high surface area.
 This presentation will describe the development and application of a high-throughput methodology to accelerate the exploration of the effects of composition and synthesis parameters on the activity of perovskite oxide and metal-organic framework-derived alkaline electrolyte OER catalysts. The evolution of the oxidation state and atomic structure of the MOF materials in the electrochemical environment, as determined using in situ X-ray absorption spectroscopy (XAS), as well as the evolution of the morphology of the catalyst, as determined using electron microscopy, will be described.
 References
 
 
 
 Yang, X. Han, A.I. Douka, L. Huang, L. Gong, C. Xia, H.S. Park, and B.Y. Xia, Adv. Func. Mater., 31 (2021) 2007602.
 
 
 Pivovar, Nature Catalysis, 2 (2019) 562.
 
 
 Thompson and D. Papageorgopoulos, Nature Catalysis, 2 (2019) 558.
 
 
 Hwang, R.R. Rao, L. Giordano, Y. Katayama, Y. Yu, and Y. Shao-Horn, Science 358 (2017) 751.
 
 
 Suntivich, K.J. May, H.A. Gasteiger, J.B. Goodenough, Y. Shao-Horn, Science, 334 (2011) 1383.
 
 
 
 Acknowledgements
 This work was supported by the U.S. Department of Energy (DOE), Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office (HFTO) under the auspices of the Electrocatalysis Consortium (ElectroCat 2.0). This work was also supported by DOE, Advanced Research Projects Agency-Energy (ARPA-E) under the DIFFERENTIATE program. This work utilized the resources of the Advanced Photon Source, a DOE Office of Science user facility operated by Argonne National Laboratory for DOE Office and was authored by Argonne, a DOE Office of Science laboratory operated for DOE by UChicago Argonne, LLC under contract no. DE-AC02-06CH11357.

Platinum Group Metal-Free Oxygen Evolution Electrocatalysts for Alkaline Water Electrolysis

Materials in the Fe-N-C family are the most promising platinum group metal-free (PGM-free) catalysts for the oxygen reduction reaction (ORR) in polymer electrolyte fuel cells (PEFCs).1-3 Although significant progress has been made in recent years in improving both the ORR activity and durability of the Fe-N-C catalysts, further improvements are needed, especially in long-term performance durability in hydrogen-air PEFCs, to enable their use in applications such as propulsion power for light-duty vehicles.3
 
 The most active ORR catalysts in the Fe-N-C family were synthesized by heat treating iron salts or other iron-containing compounds with zinc-based zeolitic imidazolate frameworks (ZIFs) and/or phenanthroline (as carbon and nitrogen sources), or by heat treating iron-substituted ZIFs. For this family of PGM-free materials, it has been shown that many synthesis variables, such as the metal and carbon-nitrogen macrocycle content, the heat treatment temperature, atmosphere, and temperature profile all affect the activity and durability of the resulting catalysts.4-7 Optimization of these variables and testing the resulting catalyst properties is not a trivial task, and only a limited portion of the composite composition and temperature space has been explored for this family of catalysts.
 To accelerate optimization of the synthesis variables to obtain improved ORR activity and stability for the Fe-N-C catalysts, high-throughput synthesis and characterization methods were developed and utilized. An automation platform, a multi-port ball-mill, and parallel fixed bed reactors in Argonne’s High-throughput Research Laboratory were used to rapidly synthesize the PGM-free catalysts with systematically-varied synthesis conditions. A multi-channel flow double electrode (m-CFDE) cell and other cells were designed and constructed for the simultaneous testing the ORR activity and stability of the multiple catalysts synthesized. The ORR activity and stability of the catalysts were correlated with their Fe speciation, as determined using Fe K-edge X-ray absorption spectroscopy (XAFS), electrochemically-determined surface areas, and other variables, which is beneficial for the further improved catalyst activity and stability.
 References 
 
 B. Pivovar, Nature Catalysis, 2 (2019) 562.
 
 
 S. Thompson and D. Papageorgopoulos, Nature Catalysis, 2 (2019) 558.
 
 
 L. Osmieri, J. Park, D.A. Cullen, P. Zelenay, D.J. Myers, and K.C. Neyerlin, Curr. Opin. Electrochem., 25 (2021) 100627.
 
 
 X. Wang, H. Zhang, H. Lin, S. Gupta, C. Wang, Z. Tao, H. Fu, T. Wang, J. Zheng, G. Wu, and X. Li, Nano Energy, 25 (2016) 110.
 
 
 H. Zhang, S. Hwang, M. Wang, Z. Feng, S. Karakalos, L. Luo, Z. Qiao, X. Xie, C. Wang, D. Su, Y. Shao, and G. Wu, J. Am. Chem. Soc., 139 (2017) 14143-14149.
 
 
 E. Proietti, F. Jaouen, M. Lefevre, N. Larouche, J. Tian, J. Herranz, and J.-P. Dodelet, Nature Comm. 2 (2011) 1.
 
 
 A. Zitolo, V. Goellner, V. Armel, M.-T. Sougrati, T. Mineva, L. Stievano, E. Fonda, and F. Jaouen, Nature Materials, 14 (2015) 937.
 
 
 
 This work was supported by the U.S. Department of Energy (DOE), Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office (HFTO) under the auspices of the Electrocatalysis Consortium (ElectroCat). This work utilized the resources of the Advanced Photon Source, a U.S. DOE Office of Science user facility operated by Argonne National Laboratory for DOE Office and was authored by Argonne, a U.S. Department of Energy (DOE) Office of Science laboratory operated for DOE by UChicago Argonne, LLC under contract no. DE-AC02-06CH11357.

Magali Ferrandon

Papers

High Throughput Synthesis of Perovskite Oxides for Alkaline Oxygen Evolution Reaction Electrocatalysis: Nature of the a and B Sites

Nitric Oxide Probe Molecule Studies of Iron-Nitrogen-Carbon PEMFC Oxygen Reduction Reaction Electrocatalysts

Platinum Group Metal-Free Oxygen Evolution Electrocatalysts for Alkaline Water Electrolysis

Optimization of Synthesis Variables Towards Improved Activity and Stability of Fe-N-C PGM-Free Catalysts