Density Functional Theory Study of Gas Adsorption on Lanthanum Zirconate Nanostructured Coating Surface

Abstract

Lanthanum zirconate (La2Zr2O7) is a typical pyrochlore ceramic material, which can be used as thermal barrier coating (TBC). However, it may deteriorate by oxidizing and corrosive gases, such as CO2, O2, SO2 and CH4 during its operation process at elevated temperatures. This work investigates CO2, O2, SO2 and CH4 gas adsorption mechanism on La2Zr2O7 nanostructured coating surfaces using the density functional theory (DFT) calculations. La2Zr2O7 surface energies on (001), (011) and (111) planes were calculated. Results show the most thermodynamically stable surfaces of La2Zr2O7 are (011) and (111) planes, due to their low surface energies. Adsorption energies of CO2, O2, SO2 and CH4 on (001), (011) and (111) planes in different sites were studied as well. The results show the most favorable gas adsorption sites for CO2, O2, SO2 and CH4 occur at 3-fold and 4-fold sites. The most favorable gas adsorption plane for CO2, O2, SO2 and CH4 is (111) plane.