Supplemental Information Visible light photoelectrochemical sensor based on Au nanoparticles and molecularly imprinted poly(o-phenylenediamine) modified TiO2 nanotubes for specific and sensitive detection chlorpyrifos

The Ti foil (0.1 mm thickness, 99.6 % purity, Goodfellow, England) was cleaned by using distilled water and acetone and dried off with N 2 gas. The bare Ti foil was anodized in an ethylene glycol solution containing NH 4 F (0.38 wt%) and H 2 O (1.79 wt%) and placed in a well-insulated bath for 3 h at 30 V and at 20 ℃ using a dc power supply (N5753A model, Agilent). The textured Ti surface was obtained by removing the first anodized TiO 2 nanotubular layer with an adhesion tape. Subsequently, the second anodization was performed for 5 min under conditions identical to those in the first anodization step. After the second anodization step, the sample was washed with distilled water and acetone and then dried off with N 2 gas. The as-formed TiO 2 NTs have an amorphous structure but the phase can be converted into anatase or rutile through annealing. Thus, thermal annealing of the anodized TiO 2 NTs was carried out 500 ℃ for 2 h with