Optimization of electrocatalysts for fuel cell applications without alloying: a joint theoretical and experimental study

• Applicants: Professor Dr. Aliaksandr Bandarenka; Professor Dr.-Ing. Alessio Gagliardi
• Subject Area: Physical Chemistry of Solids and Surfaces, Material Characterisation ; Experimental Condensed Matter Physics
• Term: from 2017 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 355784621

Heterogeneous catalysis, including electrocatalysis is among the pillars determining the standards of life nowadays, as catalysts are among the key materials in the modern industry. Fundamental understanding of the mechanisms controlling numerous catalytic properties is therefore of significant importance. One of the most substantial challenges in catalysis today is to develop active and stable materials capable of accelerating key reactions in fuel cells, with a prime focus being set on the oxygen reduction reaction (ORR) taking place at the cathode side of these devices. It has been estimated that increasing the ORR-activity of current Pt electrocatalysts in polymer electrolyte membrane fuel cells (PEMFCs) by ~4-5 times would reduce the necessary amount of this expensive material per vehicle to that averagely used in the catalytic convertors of normal combustion engine cars nowadays (i.e. only to ~4-5g from the current ~20g). Myriads of catalysts were reported recently to address this challenge. One of the main focuses in these efforts was elaboration of alloys of platinum with transition metals. Indeed the activity of Pt can be improved by up to 10 times (Pt-Ni system) compared to pure Pt. However, certain stability issues so far largely limit the use of them. This project uses recent experimental discoveries and fundamental understanding of how one can increase the activity of the surface of pure Pt by at least the factor of 3.5-4.5 without any alloying to design active and more stable electrocatalysts for the oxygen reduction reaction. The key fact in this approach is that it is possible to increase the activity of e.g. Pt by controlling the atom coordination near to the ORR active sites. The aim of this project is to elucidate and implement 3D quasi-open structures with the maximum density of active sites of right coordination, improved stability and local mass transport properties. Successful realization of the proposed project would not only clearly demonstrate the researchers and engineers how to improve the existing materials even without alloying; it would likely establish an entirely new methodology for the development of heterogeneous electrocatalysts based on a combination of theoretical calculations of different levels and experimental approaches which elaborate open 3D-nanostructured materials applicable in the real-world electrocatalysis.

• DFG Programme: Research Grants