(289c) Effect of Doping on the Activity of Nickelate Oxides Toward Surface Oxygen Exchange and Oxygen Reduction
The surface lattice O diffusion into the bulk to form surface O vacancy is investigated first, and two possible diffusion pathways are proposed. The apical O assisted pathway is found to be more favorable. We find that the surface chemistry of La2NiO4 can indeed be tuned via modification of the Ni B-site and La A-site. With the B-site metal changing from Mn, Fe, Co, to Ni, the calculated binding energy of O2 on the surface O vacancy neighboring the transition metal becomes gradually weaker. Moreover, the barrier for O2 dissociation becomes linearly higher as the binding energy of O2 becomes weaker, whereas, the surface O vacancy formation energy becomes lower. A volcano-type relationship between the calculated rates and the binding energies of O2 is found, suggesting that the binding energy of O2 might be a good descriptor to screen for nickelate oxides with optimal oxygen exchange activity.
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