Electrodeposition of Au nanoparticles on ITO/PDAC/2H-MoS2 electrode for sensitive determination of bisphenol-A

Abstract

Exfoliated 2H-MoS₂ holds a promising future for various electrochemical applications. Nevertheless, its electrical conductivity and electrocatalytic efficiency are limited, restricting its standalone use. To address this limitation, this study proposes the electrochemical deposition of gold nanoparticles on layer-by-layer films of poly(diallyl dimethylammonium) hydrochloride interspersed with exfoliated 2H-MoS₂, previously assembled on ITO substrate. This modified electrode, denoted as ITO/PDAC/2H-MoS₂/Au, was assessed for its effectiveness in the voltametric detection of bisphenol-A (BPA). The optimal electrode architecture demonstrated a linear BPA detection range (0.9 µM-19 µM; R² > 0.99), with a limit of detection of 23 nM. Notably, the electrochemical deposition was effective on both bare and film modified ITO substrates. However, it was on the ITO/PDAC/2H-MoS₂/Au electrode that BPA detection achieved a reasonable level of sensitivity. During electrodeposition, superficial Mo(IV) is oxidized to Mo(VI) while sulfur vacancies are generated. These defect sites enhance the electrochemical activity of 2H-MoS₂ and play a pivotal role in nucleating, growing, and immobilizing gold nanoparticles, which collectively enhance the sensor’s performance.