Study and optimization of glycerol electro-oxidation on a Cu2O catalyst: experimental approach and modeling via response surface methodology based on box–behnken design
摘要
This study presents the design and optimization of copper(I) oxide (Cu2O) thin films as electrocatalysts for glycerol electro-oxidation in alkaline environments. Cu2O films were synthesized via electrodeposition on copper substrates using a citric acid-based electrolyte, chosen for its low toxicity and complexing properties. The study systematically optimized key deposition parameters such as temperature (55–75 °C), stirring rate (0–300 r min−1), scan rate (10–100 mV s−1), and precursor concentration (0.05–0.07 mol L−1) using Response Surface Methodology (RSM) coupled with a Box-Behnken Design (BBD). The optimized conditions (75 °C, 300 r min−1, 55 mV s−1, 0.06 mol L−1) resulted in the formation of a homogeneous, adherent Cu₂O film with a thickness of 420.69 nm, predicted by a statistically validated quadratic model (R2 = 0.9768). Structural analysis by X-ray diffraction (XRD) confirmed the formation of pure Cu2O in the cubic cuprite phase. Optical microscopy revealed a smooth and uniform surface, which is vital for electrocatalytic applications. Electrochemical testing showed that the Cu₂O film stabilized the open circuit potential at -0.1150 V vs. Ag/AgCl, indicating surface passivation. Cyclic voltammetry (CV) in an alkaline glycerol solution (0.5 mol L−1) exhibited two oxidation peaks at − 0.01 V and + 0.23 V vs. Ag/AgCl, confirming the electrocatalytic activity of the Cu₂O film. Chronoamperometric measurements at + 0.2 V vs. Ag/AgCl for 40 min revealed a stable current density (~ 2.41 mA) for the thicker film, indicating improved electrocatalytic performance due to a larger electroactive surface area. These results demonstrate that Cu2O thin films, synthesized under optimized conditions, exhibit promising catalytic activity for glycerol electro-oxidation, offering an alternative to noble metal-based catalysts.