Investigation of Ni-based alloy/CGO electro-catalysts as protective layer for a solid oxide fuel cell anode fed with ethanol

Abstract

Ni-based alloys were prepared by using the oxalate method and subsequent in-situ reduction. The crystallographic phase and microstructure of the catalysts were investigated. These bimetallic alloys were mixed with gadolinium-doped ceria in order to obtain a composite material with mixed electronic-ionic conductivity. Catalytic and electrocatalytic properties of the composite materials for the conversion of ethanol were investigated. Electrochemical tests were carried out by utilizing the Ni-based alloy/CGO cermet as a barrier layer in a conventional anode-supported solid oxide fuel cell (SOFC). A comparative study between the modified cells and a conventional anode-supported SOFC without the protective layer was made. The aim was to efficiently convert the fuel directly into electricity or syngas (H2 and CO) just before the conventional anode support. In accordance with the ex-situ catalytic tests, the SOFC anode modified with Ni–Co/CGO showed superior performance towards the direct utilization of dry ethanol than the bare anode and that modified with Ni–Cu/CGO. A peak power of 550 mW cm−2 was achieved with the dry ethanol-fed Ni–Co/CGO pre-layer modified-cell at 800 °C. A total low frequency resistance of <0.5 Ω cm2 at 0.8 V of cell voltage was recorded in the presence of ethanol directly fed to the SOFC.