Utilization of response surface methodology in the optimization of electrodeposition preparation of FTO/AuNPs electrodes

In this research, gold nanoparticles coated on fluorine-doped tin oxide glass (AuNPs/FTO) electrodes were synthesized via electrodeposition of HAuCl₄ in H₃PO₄ using cyclic voltammetry. For response surface methodology (RSM), a central composite design model consisting of 16 runs with three different electrodeposition parameters, such as potential window, scan rate and cycle number was used to optimize the preparation parameters. Optimization and experimental data analysis using RSM were performed using Design Expert 11 statistical data analysis program. Data was fitted into a polynomial equation that shows all of the possible interactions of the parameters and their effects on the response (the electrocatalytic activity in the 5 × 10^-3 M K₃[Fe(CN)₆] in 0.5 M KNO₃ solutions by cyclic voltammetry). The optimized preparation parameters consist of potential window ranging from − 0.51 V to 0.6 V, scan rate of 81 mV.s^-1, and cycle number of 70, and with the current density of 965.909 µA.cm^-1. These factors have been compared with the experiment and the results show that there is no large error, which proves that the model can provide good repeatability and accurate optimization. For the As(III) determination, the sensitivity, LOD and LOQ values of the optimized electrode were found to be 1.5 µA.cm^-2.ppb^-1, 1.13 ppb and 3.43 ppb, respectively, indicating that the fabricated electrode can be applied for the determination of aqueous arsenic.