Hierarchical Structured TiO ₂ /Boron‐Doped Diamond for Efficient Photo‐Electrocatalytic Degradation

ABSTRACT The discharge of refractory organic dye wastewater poses a significant threat to the ecological environment, necessitating the development of efficient treatment technologies. Herein, a uniform TiO 2 array (TiO 2 ‐AR) electrode is fabricated using a combination of magnetron sputtering and a mask plate process with a boron‐doped diamond (BDD) substrate for Reactive Blue 21 organic wastewater treatment. Photo‐electrochemical (PEC) measurements were conducted to evaluate the photo‐electrochemical behaviors of TiO 2 ‐AR, the TiO 2 ‐BDD electrode with a full layer of TiO 2 on the BDD substrate, and the pure BDD electrode. The PEC results show that the TiO 2 ‐AR/BDD electrode significantly outperforms both the TiO 2 /BDD electrode and the BDD electrode. The degradation rate of RB21 simulated wastewater by the TiO 2 ‐AR/BDD electrode is 2.32‐fold and 1.57‐fold higher than that by the TiO 2 /BDD electrode and the BDD electrode, respectively. The radical quenching experiments verify that hydroxyl radicals (•OH) are the main reactive oxygen species responsible for the degradation of RB21. The reaction pathways for the degradation of RB21 are then confirmed by HPLC‐MS and theoretical calculations. Moreover, the toxicity of the degradation intermediate of RB21 is estimated quantitatively with a quantitative structure‐activity relationship (QSAR), faithfully evidencing that both acute and chronic toxicities were effectively decreased after degradation. This work presents an efficient surface modification approach that integrates photocatalysis and electrocatalysis synergistically for wastewater treatment.