Photoelectrochemical determination of Pb2+ ions by using TiO2 nanorod arrays grown on FTO substrates via a facile two-stage hydrothermal route

Aligned TiO2 nanorod arrays (NRAs) were fabricated on TiCl4 pretreated fluorine doped tin oxide (SnO2:F, FTO) substrates by a facile hydrothermal route. The effects of TiCl4 concentration (20, 40 and 60 mM) and post-growth treatments were investigated on the PEC performance of TiO2 NRAs. The optimal PEC performance, owning a low Pb2+ detection limit of similar to 2 nM, was achieved in the TiO2 NRAs which was pretreated with 20 mM TiCl4 and sintered after growth. It implied that the modification of FTO substrates with a low TiCl4 concentration was critical for achieving the ideal morphology and performance of TiO2 NRAs which reached a balance of light harvesting, carrier transport and ion diffusion. Additionally, it was also worth mentioning that the TiCl4 post-treatment wasn't beneficial to improve the PEC performance of the compact TiO2 NRAs.