Photoelectrocatalytic determination of chemical oxygen demand under visible light using Cu2O-loaded TiO2 nanotube arrays electrode

A novel, visible light responsive chemical oxygen demand (COD) determination method using a Cu2O-loaded TiO2 nanotube arrays (TNTAs) electrode as sensor was proposed. In comparison with the pure TNTAs, the composite electrode showed much enhancement in the photocurrent response in visible region. With a positive bias potential of 0.3 V (vs. Ag/AgCl) and visible light illumination, a COD detection limit of 15 mg L−1 COD and a linear range of 20–300 mg L−1 COD were achieved by the present composite electrode. When the composite electrode was used for the test of real wastewater samples, the obtained values were in good agreement with those determined by the standard K2Cr2O7 COD determination method. This paper would provide a potential outdoor COD determination method utilizing solar energy.