Catalytic surface promotion of highly active La0.85Sr0.15Cr0.8Ni0.2O3−δ anodes for La5.6WO11.4−δ based proton conducting fuel cells

Abstract

La0.85Sr0.15CrO3−δ (LSC), La0.85Sr0.15Cr0.8Ni0.2O3−δ (LSCN) and LSCN infiltrated with Ni nanoparticles were tested as anodes for symmetrical cells based on La5.6WO11.4−δ (LWO) protonic electrolyte. These chromite-based electrode materials are compatible with LWO material, in contrast to the widely used NiO. Under typical anode reducing conditions, Ni is segregated from the LSCN lattice on the grain surface as metallic Ni nanoparticles, which are proved to be compatible with LWO in reducing conditions. These Ni nanoparticles become the catalytic active sites for the H2 oxidation reaction in proton conducing anodes and the electrode performance is substantially improved regarding to pure LSC. Ni nanoparticle infiltration further improves the catalytic promotion of the anode, reducing the polarization resistance (Rp) previously limited by low frequency surface related processes. Indeed, the Rp values achieved for LSCN infiltrated with Ni, e.g. 0.47Ωcm2 at 700°C, suggest the practical application of this kind of anodes in proton conducting solid oxide fuel cells (PC-SOFC).