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[Display omitted] • Electrophoretic deposition method to prepare biochar electrode. • ZnO modification increases mesoporous volume, hydrophilicity and conductivity. • Betaine introduce more reversible redox-active N-functional group. • BK-Z15%-N electrode shows high electro-sorption capabilities and good regeneration. In this work, functional mesoporous bean dregs-based biochar electrodes were prepared by electrophoretic deposition for perchlorate (ClO 4 -) electro-sorption. We characterized the textural and electrochemical properties of the biochar and determined the kinetics of electro-adsorption. The results show that 15% concentration of ZnO nanoparticle modification is recommended to increase the mesoporous volume, specific surface area, hydrophilicity and conductivity of biochar materials. After betaine functionalization, the obtained biochar (BK-Z15%-N) possesses an excellent electrochemical performance with high current density, charging capacity, and low ohmic impedance. As expected, it presents an electro-adsorption capacity of 28.31 mg g-1 toward 20 mg L-1 ClO 4 - at 1 V, which is four times higher than that without voltage and much better than other electrodes in this study and most reported data. The electro-adsorption of ClO 4 - on BK-Z15%-N electrode fits the fractal model, which is a complex process controlled by the electrical force and independent of solution pH. BrO 3 - and Cl- are the most competitive anion to ClO 4 - electro-sorption. Notably, it maintains a sustainable electrochemical regeneration ability due to the reversible redox activity of quaternary amine groups. Therefore, this study offers a remarkable and reliable method for improving the electro-sorption performance of perchlorate. [ABSTRACT FROM AUTHOR]