Unveiling The Effect of Dopants on the Hydration Reaction and Proton Conduction of Nd and Y Co-Doped BaZrO <sub>3</sub> in Solid Oxide Fuel Cells
Lei He, Feng Zhang, Yan Xuan, Lei Zhang, Huiying Gao, Huaqing Pan, Sen Lian, Mingyue Wang, Jikang Yin, Chen Xue, Junfeng Ren, Meina Chen
Abstract
Both surface and bulk properties on hydration reaction and proton conduction of Nd and Y co-doped BaZrO 3 (BZNY) were investigated for the first time by first-principles calculations. The effects of Nd and Y on oxygen vacancies in BaZrO 3 are opposite to those in BaCeO 3 , which allows us to break away from the traditional misunderstanding that the larger the radius of the doped ion, the easier it is to form oxygen vacancies. We can also infer from the calculation that the hydration reaction has a negative correlation with the formation of oxygen vacancies. Both oxygen vacancies and protons were calculated to have a tendency to accumulate on the BZNY surface, which facilitates promoting surface hydration reaction. It is worth noting that Nd and Y reduce the difference in proton stability of the layers near the surface, therefore promote proton transmission. Unexpectedly, Y 3+ (0.900 Å) was calculated to be more likely to segregate in BZNY than Nd 3+ (0.983 Å), which subverts our traditional view that doped ions with larger radius are easier to segregate. Moreover, for proton transport though the grain boundaries, the segregation of Nd and Y were also predicted to have beneficial effects in BZNY.