An Enhanced Electrochemical Catalytic Activity Towards Arsenic (III) Detection Based on FTO Electrode Modified with Gold Nanoparticles by Irradiation and Electrophoretic Deposition

In this work, the electrophoretic deposition (EPD) of gold nanoparticles (AuNPs) on the fluorine-doped tin oxide (FTO) electrode in ethanol solution obtained from irradiation was employed to fabricate the FTO/AuNPs electrode, which was used for As(III) detection in aqueous media. The AuNPs solution was obtained through the Co-60 isotope irradiation of chloroauric acid solution in ethanol, and the electrophoretic deposition was performed at a constant voltage of 100 V for 30 min using the ethanolic AuNPs solution. The EPD conditions were optimized using cyclic voltammetry in hydroquinone/sodium perchlorate solution. The SEM images, as well as EDX results, confirmed the uniform decoration of gold nanoparticles on the FTO electrode with the particles size in the range of 100 – 200 nm and the particles' morphology of spiked nanospheres. For As(III) detection, the measurements were conducted using square wave anodic stripping voltammetry in potential range from -0.3 to 0.5 V (vs. Ag/AgCl) with 75 mV amplitude and 25 Hz frequency in 0.05 M sulfuric acid (pH = 1), with the stripping step being controlled at -0.5 V for 300 s. The FTO/AuNPs exhibited great electrochemical catalytic activity and superior As(III) sensitivity with a linear range from 1 to 50 ppb (R 2 = 0.998), a high sensitivity of 0.002 mA ppb −1 cm −2 and a low LOD value of 0.008 ppb.