CeO2 with fusiform structures were prepared by the combined microwave–ultrasonic method, and their morphologies and surface structure were changed by simply adding different amounts of H2O (1–5 ml) to the precursor system. The addition of H2O changed the PVP micelle structure and the surface state, resulting in CeO2 with a different specific surface area (64–111 m2 g−1) and Ce3+ defects (16.5%–28.1%). The sample with 2 ml H2O exhibited a high surface area (111.3 m2∙g−1) and relatively more surface defects (Ce3+%: 28.1%), resulting in excellent catalytic activity (4.34 mmol g−1 h−1).
1. Fusiform-like CeO2 was prepared by the combined microwave–ultrasonic method.
2. 1–5 ml H2O in the precursor can influence the morphology, surface area, and Ce3+% of the CeO2 catalyst.
3. H2O changed the PVP micelle structure, leading to modulation of the CeO2 surface state.
4. For imine synthesis, CeO2 with 2 ml H2O showed 2-times higher activity than the control without H2O.