Electrocatalysis for low-temperature fuel cells
Image credit: M. Escudero-Escribano et al., Science (2016).
Fuel cells convert the chemical energy from hydrogen or liquid fuels such as formic acid, methanol or ethanol, directly into electricity. The oxygen reduction reaction (ORR) largely limits a fuel cell. This reaction is of fundamental importance for sustainable energy conversion. Its slow kinetics limits the performance of sustainable energy conversion devices such as low-temperature fuel cells. Under acidic conditions, at which proton exchange membrane fuel cells (PEMFCs) operate, only Pt-based catalysts are both active and stable for this reaction. Our research on both model and nanoparticulate ORR catalysts has led to significant breakthroughs in the field of electrocatalysis. In addition to the ORR, we investigate new catalyst materials for the electrochemical oxidation of liquid fuels such as formic acid.
Image credit: K. Ehelebe et al., ACS Energy Letters (2022).
Over the past decades, enormous efforts have been made in the development of active Pt-based nanocatalysts. Most of the works are typically carried out in rotating disk electrodes (RDEs). However, the activity enhancement does not typically translate to technologically relevant membrane electrode assemblies (MEAs). In our lab, we combine fuel-cell electrocatalyst benchmarking in traditional liquid-based setups such as RDEs with gas diffusion electrode (GDE) half-cells to improve the mass transport of gases such as oxygen and allow electrochemical measurements at high current densities at which fuel cells operate.
Key publications:
M. Escudero-Escribano*, P. Malacrida, M.H. Hansen, U.G. Vej-Hansen, A. Velazquez-Valenzuela, V. Tripkovic, J. Schiøtz, J. Rossmeisl, I.E.L. Stephens*, I. Chorkendorff*, “Tuning the activity of Pt alloy electrocatalysts by means of the lanthanide contraction” Science, 2016, 352, 73. “Highly cited paper” (“top 1% in the field of Chemistry”, Web of Science).
K. Ehelebe*, N. Schmitt, G. Sievers, A.W. Jensen, A. Hrnjic, P. Collantes-Jimenez, P. Kaiser, M. Geuss, Y.-P. Ku, P. Jovanivic, K. J.J. Mayrhofer, N. Hodnik, B. Etzold, M. Escudero-Escribano, M. Arenz, S. Cherevko*, “Benchmarking fuel cell electrocatalysts using gas diffusion electrodes: inter-lab comparison and best practices”, ACS Energy Letters, 2022, 7, 816.
G.W. Sievers*, A.W. Jensen, J. Quinson, A. Zana, F. Bizzotto, M. Oezaslan, …, K. Cépe, M. Escudero-Escribano, J. Rossmeisl, A. Quade, V. Brüser, M. Arenz, “Self-supported Pt-CoO networks combining high specific activity and high surface area for oxygen reduction”, Nature Materials, 2022, 20, 208.
G. Sievers, A.W. Jensen, V. Brüser, M. Arenz*, M. Escudero-Escribano*, “Sputtered Pt thin films for oxygen reduction in gas diffusion electrodes – a model system for studies under realistic conditions”, Surfaces, 2019, 2, 336.
M. Inaba, A.W. Jensen, G. Sievers, M. Escudero-Escribano, A. Zana, M. Arenz*, “Benchmarking high surface area electrocatalysts in a gas diffusion electrode: measurement of the oxygen reduction activities under realistic conditions”, Energy and Environmental Science, 2018, 11, 988.
M. Escudero-Escribano*, K.D. Jensen, A.W. Jensen, “Recent advances in the development of bimetallic electrocatalysts for oxygen reduction: design principles, structure-function relations and active phase elucidation”, Current Opinion in Electrochemistry, 2018, 8, 135.
K.D. Jensen, J. Tymoczko, J. Rossmeisl, A.S. Bandarenka, I. Chorkendroff, M. Escudero-Escribano*, I.E.L. Stephens*, “Elucidation of the oxygen reduction volcano in alkaline media using a copper-platinum(111) alloy”, Angewandte Chemie International Edition, 2018, 57, 2800. [Frontispiece of Angewandte Chemie and VIP. Research highlights in Nature Reviews Chemistry and Nature Catalysis]