Electrocatalysis is emerging as a promising alternative to bacterial denitrification for removing nitrate and ammonia from sewage. The technology is highly efficient and robust in actual wastewater treatment scenarios; however, there may be the generation of harmful intermediates (such as nitrite) on the traditional cathode material. In this study, we demonstrated that TiO₂ nanotube arrays can be used as an effective cathode to reduce nitrate to ammonia without generation of nitrite. Alongside this, the addition of chloride ions in the solution can further oxidize ammonia to N₂. We looked into the key factors influencing the electrocatalytic denitrification, including the current density (2–10 mA/cm²), initial pH values (3–11), and types of anions (HCO₃⁻, Cl⁻, SO₄²⁻). The results showed that 90.8% of nitrate and 59.4% of total nitrogen could be removed in 1.5 h under optimal conditions, with degradation kinetic constants of 1.61 h⁻¹ and 0.79 h⁻¹, respectively. Furthermore, we investigated the formation of intermediate products and explored the electrocatalytic denitrification mechanism: (a) the surface oxygen vacancies and high specific surface area of TiO₂ nanotube arrays electrode promote the reduction of nitrate to ammonia and N₂; (b) the active chlorine generated at the anode surface can effectively oxidize ammonium to N₂.

电催化作为细菌反硝化从污水中去除硝酸盐和氨的一种有前途的替代方法正在兴起。该技术在实际废水处理场景中非常高效且可靠；但是，传统的阴极材料上可能会产生有害的中间体（例如亚硝酸盐）。在这项研究中，我们证明了TiO ₂纳米管阵列可以用作有效的阴极，以将硝酸盐还原为氨而不会产生亚硝酸盐。除此之外，在溶液中添加氯离子可将氨进一步氧化成N ₂。我们研究了影响电催化反硝化的关键因素，包括电流密度（2-10 mA / cm ²），初始pH值（3-11）和阴离子类型（HCO₃ ^- ，氯^-，SO ₄ ^2-）。结果表明，在最佳条件下，在1.5 h内可去除90.8％的硝酸盐和59.4％的总氮，降解动力学常数分别为1.61 h ^-1和0.79 h ^-1。此外，我们研究了中间产物的形成并探讨了电催化反硝化的机理：（a）TiO ₂纳米管阵列电极的表面氧空位和高比表面积促进硝酸盐还原为氨和N ₂；（b）在阳极表面产生的活性氯可以有效地将铵氧化为N ₂。