Modification of Screen-printed Carbon Electrodes with Gold Particles to Enhance Luminol Electrochemiluminescence for Hydrogen Peroxide Detection

Screen-printed carbon electrodes (SPCEs) were modified with gold particles to improve luminol electrochemiluminescence (ECL) in the presence of H₂O₂ as the co-reactant. Gold particles with sizes ranging from 10 to 50 nm were successfully deposited by the electrochemical technique with around 3.4% (w/w) gold on the carbon surface. The gold-modified SPCE (Au-SPCE) increases the ECL intensity of luminol around 2.5 times more than that using the unmodified SPCE. These signals were also found to be linearly correlated to H₂O₂ concentration. At an optimum pH of 9, the ECL signals of 1 mM luminol in 0.1 M phosphate buffer solution using the Au-SPCE are linear in the H₂O₂ concentration range from 0.5 to 200 µM (R² = 0.99) with an estimated detection limit of 4.78 µM. The developed sensor also showed the excellent repeatability and reproducibility of the ECL signals. Moreover, H₂O₂ detection in milk and tap water samples was also successfully demonstrated, indicating that the developed sensor is promising for H₂O₂ detection applications.