This study investigates the synergistic enhancement of nitrate reduction to nitrogen gas (N₂) in water using Pd–Cu bimetallic single-atom electrocatalysts (Pd–Cu-N-BC). The catalysts were prepared by directly growing Pd–Cu single atoms on bamboo biochar, a nitrogen-doped material, through an impregnation-calcination-reduction method. The electrocatalytic performance of Pd–Cu-N-BC was evaluated in a 3D electrocatalytic system, demonstrating excellent catalytic activity and reusability. The catalyst exhibited a low potential of 0.47 V vs. RHE (@10 mA cm⁻²) for nitrate reduction and achieved a maximum nitrate removal efficiency and N₂ generation of about 100% and 72.32%, respectively, within 180 minutes. Density functional theory (DFT) calculations confirmed that Cu atoms catalyze the electrochemical reduction of nitrate to nitrite, while Pd atoms in the nitrogen-doped biochar lattice catalyze the reduction of nitrite to N₂, involving the formation of hydrogen radicals (H⁺). The electronic synergistic effect between Pd and Cu atoms significantly promotes N₂ production while inhibiting the formation of byproducts. The 3D particle electrode design of Pd–Cu-N-BC showed excellent stability and reusability, making it a promising candidate for the remediation of nitrate contamination in water.This study investigates the synergistic enhancement of nitrate reduction to nitrogen gas (N₂) in water using Pd–Cu bimetallic single-atom electrocatalysts (Pd–Cu-N-BC). The catalysts were prepared by directly growing Pd–Cu single atoms on bamboo biochar, a nitrogen-doped material, through an impregnation-calcination-reduction method. The electrocatalytic performance of Pd–Cu-N-BC was evaluated in a 3D electrocatalytic system, demonstrating excellent catalytic activity and reusability. The catalyst exhibited a low potential of 0.47 V vs. RHE (@10 mA cm⁻²) for nitrate reduction and achieved a maximum nitrate removal efficiency and N₂ generation of about 100% and 72.32%, respectively, within 180 minutes. Density functional theory (DFT) calculations confirmed that Cu atoms catalyze the electrochemical reduction of nitrate to nitrite, while Pd atoms in the nitrogen-doped biochar lattice catalyze the reduction of nitrite to N₂, involving the formation of hydrogen radicals (H⁺). The electronic synergistic effect between Pd and Cu atoms significantly promotes N₂ production while inhibiting the formation of byproducts. The 3D particle electrode design of Pd–Cu-N-BC showed excellent stability and reusability, making it a promising candidate for the remediation of nitrate contamination in water.