A simple process for the deposition of TiO2 onto BDD by electrophoresis and its application to the photoelectrocatalysis of Acid Blue 80 dye.

A 4 cm 2 BDD/TiO 2 electrode has been synthesized by a novel method in which nano-particulated TiO 2 (P25, Degussa) was electrophoretically deposited onto a boron-doped diamond (BDD) substrate, followed by sintering at 450 °C. Its surface characteristics were analyzed by SEM-EDX. The electrocatalytic behavior of the BDD/TiO 2 electrode was clarified from the cyclic voltammetry of a 0.50 M K 4 [Fe(CN)₆] solution. The much higher electroactive area of the nano-structured TiO 2 deposit over the hybrid electrode gave much higher currents of the Fe(CN) 6 3– /Fe(CN) 6 4– pair than using the raw BDD electrode. When BDD/TiO 2 was used in the anodic oxidation of 50 mg L − 1 Acid Blue 80 solution at pH 3.0 and 5.0 at 22.5 mA cm − 2 in the dark, it decolorized much more rapidly the dye solution compared to anodic oxidation with BDD. This was related to the production of greater amounts of hydroxyl radical at the high electroactive area of the nano-structured TiO 2 . Quicker color removal was obtained by photoelectrocatalysis by irradiating the BDD/TiO 2 anode with a 75 mW cm − 2 UVA light (λ max = 365 nm). The dye concentration decay was always much faster than decolorization due to the formation of more recalcitrant colored products from the attack of oxidizing species. In 60 min, photoelectrocatalysis removed 96% of Acid Blue 80. The use of nano-structured TiO 2 deposited onto BDD as anode in photoelectrocatalysis then exceeds the efficiency of anodic oxidation with the best anode known of BDD. [ABSTRACT FROM AUTHOR]