The electrocatalytic reduction of nitrate to ammonia (NRA) is considered to be a promising and environmentally friendly alternative to the Haber-Bosch process. Herein, a simple in situ electrodeposition-reduction method is proposed, which allows for the surface reconstruction and modification of copper foil by introducing cerium. The surface modification results in the formation of Cu/Ce 2 O 3 nanoflowers on the copper electrode surface. Additionally, density functional theory calculations demonstrate that Ce 2 O 3 enhances the adsorption of NO 3 - . Compared with a pure copper electrode, the NRA performance of surface-reconstructed copper is greatly improved, with the maximum ammonia yield rate and the highest Faradaic efficiency from 24.8% to 73.0% and from 0.081 to 0.386 mmol h -1 cm -2 , respectively. The 15 N isotope labeling experiment confirms that the nitrogen source in the ammonia originated from nitrate.