Doping as a common mean to generate defects to boost the catalytic performance of metal oxide semiconductor-based materials has aroused great interest. However, doping usually requires high temperatures and is time consuming. Herein, we report a facile strategy for the preparation of F doped CeO₂ (F–CeO₂) with assistance of the electrostatic attraction between F⁻ and CeO₂ with oxygen vacancies at room temperature, then F–CeO₂ acts as superior support of metal Co nanoparticles (NPs) for efficient hydrolysis of NH₃BH₃ under light irradiation. The activity of Co/F–CeO₂ is significantly enhanced and Co/F–CeO₂-0.6 exhibited highest catalytic activity with TOF value 92.8 min⁻¹ which increases 47% compared with Co/CeO₂. Experimental and characterization results show the enhanced performance attributes to high efficiency photogenerated carrier separation and boosting adsorption capacity of H₂O and NH₃BH₃ over Co/F–CeO₂ due to F doped into CeO₂ crystallites. Furthermore, theory calculations further confirm that the band gap of F–CeO₂ becomes smaller and F–CeO₂ is more favorable the adsorption for H₂O and NH₃BH₃ than pure CeO₂. This work offers a facile and time efficiency strategy to realize controllable element doped in metal oxide under ambient, and gives deep insights into the structure–activity relationship of catalyst between defect engineering and photocatalytic performance.