Density functional theory study of the interaction of H2O, CO2 and CO with the ZrO2 (111), Ni/ZrO2 (111), YSZ (111) and Ni/YSZ (111) surfaces

摘要

The triple phase boundary (TPB),where the gas phase, Ni particles and the yttria-stabilised zirconia (YSZ) surfaceudmeet, plays a significant role in the performance of solid oxide fuel cells (SOFC). Indeed, the key reactions takeudplace at the TPB, where molecules such as H2O, CO2 and CO interact and react. We have systematically studiedudthe interaction of H2O, CO2 and CO with the dominant surfaces of four materials that are relevant to SOFC, i.e.udZrO2(111), Ni/ZrO2(111), YSZ(111) and Ni/YSZ(111) of cubic ZrO2 stabilized with 9% of yttria (Y2O3). Theudstudy employed spin polarized density functional theory (DFT), taking into account the long-range dispersionudforces.We have investigated up to five initial adsorption sites for the three molecules and have identified the geometriesudand electronic structures of the most stable adsorption configurations.We have also analysed the vibrationaludmodes of the three molecules in the gas phase and compared them with the adsorbed molecules. Auddecrease of the wavenumbers of the vibrational modes for the three adsorbed molecules was observed,udconfirming the influence of the surface on the molecules' intra-molecular bonds. These results are in line withudthe important role of Ni in this system, in particular for the CO adsorption and activation.