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 H2 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/H2 redox couple on the reduced Ni surface.