Efficient electrochemical decomposition of sulfamethoxazole using a novel free-standing TiN anode

The utilization of electrochemical oxidation (EO) processes has become increasingly popular in the field of wastewater treatment, and the robust and sustainable electrode materials were highly desirable for such processes. Among these materials, titanium nitride (TiN) has emerged as a promising candidate due to its unique electronic configuration, which impart ideal electrical conductivity similar to metals, and good stability approaching that of ceramic electrode. This study aimed to develop a free-standing TiN electrode for the EO treatment of refractory antibiotics such as sulfamethoxazole (SMX), and to evaluate its efficacy for SMX removal. The results showed that the TiN electrode achieved a high SMX removal rate (100% removal at 60 min, k_obs = 0.031 min⁻¹). Density functional theory (DFT) calculations were utilized to explicate the underlying mechanism, revealing that water oxidation on the TiN surface generates ^·OH rather than O₂, making TiN an excellent material for the mineralization of recalcitrant SMX. Additionally, both the DFT and LC-MS/MS results demonstrated that the degradation pathway of SMX was induced by ^·OH through H-abstraction and electron-transfer pathway, and the active sites responsible for the degradation intermediates were determined by DFT calculation. Overall, these findings provide valuable insights into the development of effective and environmental benign water purification method using novel, free-standing TiN anode material.