Investigation of Cathode Catalysts for Intermediate-temperature H₂S-Air Fuel Cells
By ZHONG, Li; LUO, Jingli & Karl, Chuang
Published in Chinese Journal of Chemical Engineering
2007
Abstract
Cathode catalysts comprising composite NiO, NiO-Pt, or LiNiO₂ have been developed for electrochemical oxidation of hydrogen sulfide in intermediate-temperature solid oxide fuel cells (ITSOFCs). All catalysts exhibited good electrical conductivity and catalytic activity at operating temperature. Composite NiO catalysts were found to be more active and have lower over potential and higher current density than pure Pt although the electrical conductivity of NiO itself is lower than that of Pt. This problem has been overcome by either admixing as high as 10% (by mass) Ag powder into NiO cathode layer or using composite NiO catalysts such as NiO-Pt and LiNiO₂ catalysts. Composite catalysts like NiO with Ag, electrolyte and starch admixed, NiO-Pt, which was prepared from a mixture of NiO and Pt powders, by admixing electrolyte and starch, and LiNiO₂, which is derived from the reaction of LiOH·H₂O and NiO with electrolyte and starch admixed have been shown to be feasible and effective in an intermediate-temperature H₂S-air fuel cell. A fuel cell using Li₂SO₄-based proton-conducting membrane as electrolyte, metal sulfides as anode catalysts, and composite NiO as cathode catalysts produced a maximum current density about 300mA·cm⁻² and maximum power density over 80 mW·cm⁻² at 680°C.