Copper complex containing N-acylhydrazone bulk-modified carbon paste electrode as a catalyst in ethanol electro-oxidation reaction

Abstract This study reports the electrocatalytic performance of a copper(II) N-acylhydrazone complex, dichlorido-bis[2-(4-dimethylaminophenyl)methylene]hydrazide copper(II), supported on carbon paste electrodes (Cu-CPE). The complex was synthesized and characterized by FTIR, CHN analysis, 1H NMR, UV/Vis, and thermogravimetric analysis. Electrochemical tests in acidic ethanol solution revealed that Cu-CPE electrodes exhibit significantly enhanced current responses compared to bare CPE. While the unmodified CPE displayed a current density of approximately 0.45 mA cm−2 and Cu-CPE 5% reached 1.10 mA cm−2, the Cu-CPE 30% electrode achieved 3.95 mA cm−2, corresponding to nearly a nine-fold increase over bare CPE and a 3.6-fold enhancement relative to Cu-CPE 5%. These results demonstrate that higher catalyst loading provides superior activity toward ethanol electro-oxidation. Overall, the findings highlight the potential of copper–N-acylhydrazone complexes as cost-effective catalysts for the electro-oxidation of ethanol.