A photoelectrochemical sensor for lead ion through electrodeposition of PbS nanoparticles onto TiO₂ nanotubes

A selective and sensitive photoelectrochemical sensor for lead ion (Pb²⁺), which is based on the generated photocurrents of lead sulfide (PbS) nanoparticles under visible light irradiation, has been developed with theoretical and technical simplicity. The PbS nanoparticles are in-situ electrodeposited onto TiO₂ nanotube arrays with the gradual addition of Pb²⁺. The present sensor shows high selectivity against other metal ions, broad linear range from 10^-8 M to 10^-5 M, and low detection limit of 0.39 nM (∼0.08 ppb), which is much lower than the standard of Pb²⁺ in drinking water formulated by World Health Organization (WHO). Thus, the strategy has been applied to successful detection of Pb²⁺ in tap and lake water samples. The results for determination of Pb²⁺ in lake water samples obtained by the present method and atomic adsorption spectroscopy (AAS) are consistent. However, the detection of Pb²⁺ in tap water samples has just been realized by the present method, but AAS cannot, because of its low detection limit.