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Significant improvement of electrooxidation performance of carbon in molten carbonates by the introduction of transition metal oxides
Journal article   Peer reviewed

Significant improvement of electrooxidation performance of carbon in molten carbonates by the introduction of transition metal oxides

Chang Qing Wang, Jia Liu, Jia Zeng, Jin Ling Yin, Gui Ling Wang and Dian Xue Cao
Journal of power sources, Vol.233, pp.244-251
07/2013
DOI: https://doi.org/10.1016/j.jpowsour.2013.01.016
Web of Science ID: WOS:000316827000033

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Abstract

Carbon electrooxidation Transition metal oxides Molten carbonates Direct carbon fuel cell Electrochemistry Materials Science
Solid carbon electrooxidation is the anode reaction of a direct carbon fuel cell. In this study, electrooxidation of graphite in molten carbonates containing transition metal oxides (Fe2O3, Co3O4, NiO, and MnO2) is investigated. It is demonstrated that, by dissolving transition metal oxides into the molten Li2CO3-K2CO3, the onset potential for graphite oxidation is significantly shifted to negative value and the oxidation current density is remarkably increased. At 750 degrees C, NiO causes a negative shift of onset oxidation potential by around 0.3 V and a current density (at -0.4 V) increase by 4.5 times. The coulombic efficiency of graphite oxidation remains above 94% with and without metal oxides. The apparent activation energy is reduced by more than 40 kJ mol(-1) by the addition of metal oxides. The working mechanism of the transition metal oxides is interpreted by electronegativity of metal cations, the concentration of oxygen anions and the indirect oxidation pathway via preceding chemical reaction-following electrochemical reaction.

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