Determination of Chemical Oxygen Demand Based on Novel Photoelectro‐bifunctional Electrodes

A novel photoelectro‐bifunctional electrode (TiO 2 /Ti/TiO 2 ‐Pt) for the rapid determination of chemical oxygen demand (COD) has been developed. The TiO 2 nanotubes, serving as the photocatalyst and the support of the electrocatalyst, were directly grown on both sides of a Ti plate by anodic oxidation. Pt nanoparticles were loaded on one side of TiO 2 nanotubes by the photoreduction method. For the COD determination, the bifunctional electrode exhibits a low detection limit (9.5 mg/L), high sensitivity of 3.55×10 −3 mA/(mg/L COD) and high Cl − tolerance (1400 mg/L). When used for the test of real wastewater samples, the results were in excellent agreement with those determined by the standard K 2 Cr 2 O 7 method.