A highly sensitive non-aggregation colorimetric sensor for the determination of I− based on its catalytic effect on Fe3+ etching gold nanorods

I− could accelerate the selective etching along longitudinal direction of gold nanorods (AuNRs) induced by Fe3+ in HCl medium, which decreased the aspect ratio (length/width) of AuNRs, and thus the longitudinal surface plasmon resonance (LSPR) absorption peaks of AuNRs blue shifted (Δλ = λ0 − λ), the corresponding absorbance decreased (ΔA = A0 − A), and the color of the solution obviously changed. Therefore, a non-aggregation AuNRs colorimetric sensor for the detection of I− was developed. The proposed colorimetric sensor is responsive, simple, selective and sensitive with the limit of quantization (LOQ) of 8.8 × 10−8 M. The highly accurate sensor has been used to determine the content of I− in table salt samples with the results consistent with those obtained by inductively coupled plasma-mass spectroscopy (ICP-MS). Moreover, the morphological changes of AuNRs during the etching procedure were characterized by high resolution transmission electron microscopy (HRTEM) and the sensing mechanism for I− detection was also discussed.