In this work a simple procedure was developed to prepare a Au electrode modified with CdS nanoparticles, mercaptoacetic acid and FAD. First gold electrode immersed in solution containing CdCl2 0.1 M and Na2S2O3 0.01M (pH=2). The potential of the electrode was kept at -1V for 30s. The Au/CdS modified electrode immersed into a mercaptoacetic acid and ethanol solution for 3h. Then, the Au/CdS/MAA modified electrode immersed in FAD solution at constant potential, 1V for 14min. The cyclic voltammograms of the modified electrode is shown a pair of well defined, stable and nearly reversible redox system for FAD/FADH2 with surface confined characteristics. The transfer coefficient (α), heterogeneous electron transfer rate constants (Ks) and surface concentrations (Г) for Au/CdS/Maa/FAD modified electrode were calculated using cyclic voltammetry technique. The modified electrode showed excellent catalytic activity, fast response time and high sensitivity toward reduction H2O2 and KIO4 in phosphate buffer solutions at pH range 1-12. Finally, the catalytic rate constant of the modified for selected analytes were calculated. The photoelectrocatalytic activity of the modified electrode was also investigated.
