Reduction Behavior of Ni in a Ni/YSZ Anode Revealed by Operando Fluorescence X-ray Absorption Spectroscopy

Reduction behavior of Ni at a Ni/yttria-stabilized zirconia (YSZ) anode for a solid oxide fuel cell has been investigated by using operando fluorescence X-ray absorption spectroscopic technique. Characteristic four potential regions and two reduction rates of Ni were observed during thermochemical reduction of NiO to Ni by H-2 gas at 1073 K. These characteristic regions and rates might be attributed to formation of NiO/Ni interface at the Ni/YSZ surface (in the vicinity of the gas inlet), that in the inside of the Ni/YSZ anode, and existence of H2O/H-2 redox couple on the reduced Ni surface.