Degradation of Ni-Zr0.9Sc0.1O1.95 anode in H2 + H2O at low temperature: Influence of nickel surface charge

The present paper reports on the data of the Ni-Zr0.9Sc0.1O1.95 anode polarization resistance long-term test (1500 h) at 600 degrees C in the wet hydrogen and 30% H-2 + 70% H2O. The results are presented for two type of anodes: initial and impregnated with ceria. The fast degradation of both types of anodes in 30% H-2 + 70% H2O was observed. After the long-term tests in 30% H-2 + 70% H2O at 600 degrees C, heating and exposure at 900 degrees C in wet hydrogen leads to the restore of anode performance. At the termination of the 1500 h test, the area polarization specific resistance of Ni-Zr0.9Sc0.1O1.95 remained almost unchanged as compared to the initial value, whereas for impregnated anodes the polarization resistance increased three times. The observed phenomena were explained by the OH-ions adsorption at the positively charged nickel surface. During the long-term tests at 600 degrees C the electrode microstructure did not change and the significant sintering of highly disperse ceria was not observed. (C)2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.