Synergistic effects of Ni sub(1-xCo) sub(x)-YSZ and Ni sub(1-xCu) sub(x)-YSZ alloyed cermet SOFC anodes for oxidation of hydrogen and methane fuels containing H sub(2S)

Preparation and performance of bimetallic Ni sub((1-x)Co) sub(x)-YSZ and Ni sub((1-x)Cu) sub(x)-YSZ anodes were tested to overcome common deficiencies of carbon and sulfur poisoning in SOFCs. Ni sub(1-xCo) sub(x)O-YSZ and Ni sub((1-x)Cu) sub(x)O-YSZ precursors were synthesized via co-precipitation of their respective chlorides. Single cell solid oxide fuel cells of these bimetallic anodes were tested in H sub(2, CH) sub(4), and H sub(2S/CH) sub(4) fuel mixtures. Addition of Cu[super]2+ into the NiO lattice resulted in large metal particle sizes and decreased SOFC performance. Addition of Co[super]2+ into the NiO lattice to form Ni sub(0.92Co) sub(0).08O-YSZ anode precursor produced a cermet with a large BET surface area and active metal surface area, thus increasing the rate of hydrogen oxidation for this sample. The performance of both bimetallics was found to quickly degrade in dry CH sub(4 due to carbon deposition and lifting of the anode from the electrolyte. However, Ni) sub(0).69Co sub(0.31-YSZ showed superior activity in a 10% (v/v) H) sub(2)S/CH sub(4 fuel mixture, surpassing performance with H) sub(2) fuel, thereby demonstrating the exciting prospect of using sulfidated Ni sub((1-x)Co) sub(x)-YSZ as SOFC anodes in sulfur containing methane streams. The active anode becomes a sulfidated alloy (Ni-Co-S) under operating conditions. This anode showed enhanced performance, which surpassed those of sulfidated Ni and Co anodes, thereby suggesting a synergistic behaviour in the Ni-Co-S anode.