A comparison of Pd/C, perovskite, and Ni-Fe hexacyanoferrate bifunctional oxygen catalysts, at different loadings and catalyst layer thicknesses on an oxygen gas diffusion electrode

McKerracher, R.D., Figueredo-Rodríguez, H.A., Avila-Alejo, J.O., Kwasnicki, K., Ponce De León, C., Alegre, C., Baglio, V., Aricò, A.S. and Walsh, F.C. (2018) A comparison of Pd/C, perovskite, and Ni-Fe hexacyanoferrate bifunctional oxygen catalysts, at different loadings and catalyst layer thicknesses on an oxygen gas diffusion electrode. Journal of the Electrochemical Society, 165 (7), A1254-A1262. (doi:10.1149/2.0321807jes).

Abstract

Air electrode development is one of the most challenging steps in the design of lightweight and efficient metal-air batteries and fuel cells. The best performing oxygen catalysts often contain precious metals at a high manufacturing cost. In this paper, two low-cost catalysts for the oxygen reduction (ORR) and evolution reactions (OER), based on LSFCO perovskite and Ni-Fe hexacyanoferrate, were compared with a precious metal palladium catalyst on carbon (Pd/C). LSFCO/C showed the best all-round performance as a single bifunctional catalyst but Pd/C had the strongest ORR activity. Ni-Fe hexacyanoferrate is straightforward to manufacture in industrial quantities, and is more active for the OER than palladium and LSFCO perovskite at small loadings < 5 mg cm^-2. By mixing a small loading of Pd/C with Ni-Fe hexacyanoferrate, lower overpotentials for both the ORR and OER can be reached, with the difference in potential between the two reactions being only 0.62 V at a current density of 20 mA cm^-2. The effect of catalyst loading of each catalyst on the gas-diffusion electrode was studied, and rotating disk voltammetry was used to study the catalytic behavior of the Ni-Fe hexacyanoferrate catalyst.

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Contributors

Author: C. Ponce De León

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