Electrochemical photocatalytic degradation of dye solution with a TiO₂-coated stainless steel electrode prepared by electrophoretic deposition

This study demonstrates a new model for the treatment of azo dye wastewater by means of a heterogeneous photocatalytic degradation coupled with the homogeneous electrochemical Fenton reaction, and is called electrochemical photocatalytic (ECPC) degradation. Titanium dioxide-coated stainless steel (P₂₅-TiO₂/SS) mesh was employed as a photo-anode, covered with a uniform layer of P₂₅-TiO₂ using electrophoretic deposition (EPD) in a 2-propanol suspension with 10^-4M Zn(NO₃)₂, at a deposition time of 1min. After annealing in air at 350°C for 1h, a crack-free, porous P25-TiO₂ layer of ca. 2.14μm was obtained. Potential bias was used to enhance the photocatalytic degradation of P25-TiO₂/SS towards the target pollutant, azo dye orange G, in an undivided cell under ultraviolet light irradiation. Heterogeneous photocatalytic degradation and a homogeneous electro-Fenton reaction occurred in the system simultaneously when H₂O₂ and Fe²⁺ were electrochemically generated on the graphite cathode and photo-anode, respectively, under a suitable potential bias, enhancing the de-colorization and removal of total organic carbon.