Determination of chemical oxygen demand using flow injection with Ti/TiO₂ electrode prepared by laser anneal

The method of Ti/TiO₂ photoelectrode preparation using laser-assisted sol-gel is introduced. The prepared TiO₂ film is investigated by x-ray diffraction (XRD), atomic force microscopy (AFM), electrochemical impedance spectroscopy (EIS) and amperometry, and it illustrates that the TiO₂ film mainly consists of anatase TiO₂ nanoparticles on its surface and exhibits a superior photocatalytic activity when compared with that calcined by oven. The proposed electrode is employed as a sensor for flow injection analysis (FIA) to determine chemical oxygen demand (COD). The measuring principle is based on the photocurrent responses on the electrode, which are proportional to the COD values. The linear range is 50-1000 mg l^-1, and the detection limit is 15 mg l^-1 (S/N ≤ 3). This method is characterized by short analysis time, simplicity, low environmental impact and long lifetime of the sensor. Additionally, the COD values obtained from the proposed and the conventional method agree well as demonstrated by the significant correlation between the two sets of COD values (R ≤ 0.9961, N ≤ 20).