<p>Nitrogen doping has significant effects on the photocatalytic performance of ceria (CeO₂), and the possible synergistic effect with the inevitably introduced abundant oxygen vacancies (OVs) is of great significance for further investigation, and the specifically exposed crystal faces of CeO₂ may have an impact on the performance of nitrogen-doped CeO₂. Herein, nitrogen-doped CeO₂ with different morphologies and exposed crystal faces was prepared, and its performances in the photocatalytic degradation of tetracycline (TC) or hydrogen production via water splitting were evaluated. Density functional theory (DFT) was used to simulate the band structures, density of states, and oxygen defect properties of different CeO₂ structures. It was found that nitrogen doping and OVs synergistically promoted the catalytic activity of nitrogen-doped CeO₂. In addition, the exposed crystal faces of CeO₂ have significant effects on the introduction of nitrogen and the ease of OV generation, as well as the synergistic effect of nitrogen doping with OVs. Among them, the rod-like nitrogen-doped CeO₂ with exposed (110) face (R-CeO₂-NH₃) showed a photocatalytic degradation ratio of 73.59% for TC and hydrogen production of 156.89 µmol/g, outperforming other prepared photocatalysts.</p>