A photoelectrochemical sensor for ultrasensitive dopamine detection based on composites of BiOI and Au-Ag nanoparticles

A photoelectrochemical dopamine sensor based on BiOI and AuAgNPs nanoparticles modified indium tin oxide (ITO) electrode was prepared successfully. The noble metal material AuAg significantly improved the shortcomings of poor surface conductivity and easy recombination of photogenerated electron holes in BiOI. The prepared electrode generated a significantly enhanced and stable photocurrent signal under Xe lamp irradiation. In addition, in weak acidic electrolyte solution, dopamine molecules were protonated and preferent existed in the form of cations, which were easily attracted by electrostatic and adsorbed on the surface of negatively charged AuAgNPs. As an electron donor, DA is vulnerable to oxidation to DA+ by BiOI holes, resulting in an increased anodic photocurrent. The detection limit was 0.3 pM (S/N = 3) and the dopamine concentration exhibited a nice linear relationship between 1 pM and 0.1 μM under ideal circumstances. The dopamine photoelectrochemical sensor shown strong sensitivity, a broad linearity range, and good selectivity against potential uric acid and ascorbic acid interference. This work provides a promising PEC detection platform for the detection of small and medium-sized molecules in biological analysis.