Electrochemical behavior of molten V{sub 2}O{sub 5}-K{sub 2}S{sub 2}O{sub 7}-KHSO{sub 4} systems
- Technical Univ. of Denmark, Lyngby (Denmark)
The electrochemical behavior of K{sub 2}S{sub 2}O{sub 7}-KHSO{sub 4}-V{sub 2}O{sub 5}, K{sub 2}S{sub 2}O{sub 7}-V{sub 2}O{sub 4}, and K{sub 2}S{sub 2}O{sub 7}-KHSO{sub 4}-V{sub 2}O{sub 4} melts was studied in argon and SO{sub 2}/air atmospheres using a gold electrode. In order to identify the voltammetric waves due to KHSO{sub 4}, molten KHSO{sub 4} and mixtures of K{sub 2}S{sub 2}O{sub 7}=KHSO{sub 4} were investigated by voltammetry performed with Au and Pt electrodes in an argon atmosphere. It was shown that H{sup +} reduction took place at 0.26 V vs. an Ag{sup +}/Ag reference electrode, i.e., at a potential in between the V(V) to V(IV) and V(IV) to V(III) reduction stages. The presence of KHSO{sub 4} caused an increased concentration of V(III) species in the V{sub 2}O{sub 5} containing molten electrolytes. This effect may be caused either by protonic promotion of the V(IV) to V(III) reduction or by chemical reduction of V(IV) complexes with hydrogen, formed from H{sup +} as the product of the electrochemical reduction. Both the V(V) to V(IV) reduction and the V(IV) to V(V) oxidation remained one-electron electrochemical reactions after the addition of KHSO{sub 4} (or water) to the H{sub 2}S{sub 2}O{sub 7}-V{sub 2}O{sub 5} melt. Water had no noticeable effect on the V(V) to V(IV) reduction but the V(IV) to V(V) oxidation proceeded at higher polarizations in the water-containing melts in both argon and SO{sub 2}/air atmospheres. This effect may be explained by participation of the water molecules in the V(IV) active complexes.
- Sponsoring Organization:
- Statens Naturvidenskabelige Forskningsraad, Copenhagen (Denmark)
- OSTI ID:
- 465099
- Journal Information:
- Journal of the Electrochemical Society, Vol. 144, Issue 2; Other Information: PBD: Feb 1997
- Country of Publication:
- United States
- Language:
- English
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