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Issue 57, 2014
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Effect of carbonate anions on Bi-doped Ca2Ru2O7 pyrochlores that are potential cathode catalysts for low temperature carbonate fuel cells

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Abstract

This ex situ electrochemical study investigates how the oxygen reduction reaction (ORR) on Bi-doped Ca2Ru2O7 pyrochlore catalysts is affected by the addition of carbonate to the aqueous KOH (1 mol dm−3) electrolyte. The parent Ca2Ru2O7 catalyst has been previously reported to be selective towards the generation of CO32− on the reaction of O2 with CO2 (in the presence of H2O) at the cathode of low temperature alkaline polymer electrolyte fuel cells containing alkaline anion-exchange membranes (AAEM): a target is to develop low temperature carbonate fuel cells involving CO32− conduction through the AAEM (for potential CO2 utilisation). Rotating ring disk electrode (RRDE) voltammetry was used to probe the ORR behaviours of Ca2Ru2−xBixO7−y catalysts with x = 0.25, 0.5, 0.75, and 1. The results show that as more Bi was doped into the pyrochlore catalysts, the poorer the on-set potentials compared to the parent Ca2Ru2O7 (which itself yielded a poorer on-set potential to a benchmark Pt black catalyst). Higher levels of Bi-doping tended to reduce n values with higher levels of peroxide generated: all of the pyrochlore catalysts tested gave higher peroxide yields compared to the Pt black benchmark. However, the presence of CO32− in the O2-saturated KOH (1 mol dm−3) electrolyte appeared to improve kinetic performance of the Bi-doped pyrochlore catalysts (the effect being greatest with the x = 0.75 catalyst).

Graphical abstract: Effect of carbonate anions on Bi-doped Ca2Ru2O7 pyrochlores that are potential cathode catalysts for low temperature carbonate fuel cells

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Publication details

The article was received on 02 May 2014, accepted on 20 Jun 2014 and first published on 23 Jun 2014


Article type: Paper
DOI: 10.1039/C4RA05319B
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Citation: RSC Adv., 2014,4, 30035-30045
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    Effect of carbonate anions on Bi-doped Ca2Ru2O7 pyrochlores that are potential cathode catalysts for low temperature carbonate fuel cells

    C. A. Hancock, A. L. Ong and J. R. Varcoe, RSC Adv., 2014, 4, 30035
    DOI: 10.1039/C4RA05319B

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