Understanding the oxygen-vacancy-related catalytic cycle for H2 oxidation on ceria-based SOFC anode and the promotion effect of lanthanide doping from theoretical perspectives

[Display omitted] •The catalytic cycle of H2 oxidation on lanthanide doped CeO2(111) is proposed.•The presence of oxygen vacancy reduces the catalytic activity for H2 oxidation.•Lanthanide doping promotes each elementary step in the catalytic cycle.•Sm-doped ceria performs best, consistent with the experimental observations. Lanthanide-doped ceria is known to be a promising solid-oxide-fuel-cell (SOFC) anode material. Understanding the catalytic cycle of fuel oxidation reaction on lanthanide-doped ceria is of great significance for the design of CeO2-based anode materials and catalytic processes with improved activity. Herein, we performed density functional theory (DFT) calculations on pure and Pr-, Nd-, Sm-, Gd-doped CeO2(111) to investigate the catalytic cycle of oxygen vacancy (Ov) generation and recovery in H2 oxidation process. Lanthanide doping promotes H2 dissociation, H2O formation, H2O desorption, and bulk O2− diffusion steps in the catalytic cycle. On the basis of thermodynamic and kinetic analysis, we propose that under anodic SOFC conditions, there is not a single stable Ov on pure, Pr-, Nd-, and Sm-doped surfaces because the first nearest-neighbor Ov is filled immediately upon formation, followed by the next catalytic cycle, while one Ov exists stably on Gd-doped surface, and subsequent catalytic cycle proceeds on the second nearest-neighbor vacancy site. The presence of a single Ov reduces the catalytic activity for H2 oxidation reactions on Gd-doped surface. Sm-doped ceria showed the best promotion effect for the whole Ov-related catalytic cycle, in agreement with the experimental observations.