Electrochemical nitrate reduction to ammonia (NRA) is considered a promising strategy for environmental protection and energy saving because it can simultaneously achieve nitrate wastewater treatment and ammonia synthesis. However, currently, this method suffers from the lack of efficient electrocatalysts. In this work, through a “killing two birds with one stone” strategy, a catalyst, TiO₂@C/Fe₂O₃ nanosheet arrays (NSAs), was fabricated by introducing hydrothermal carbon (HTC), which not only accelerates the charge transfer due to its good conductivity but also provides abundant oxygen vacancies owing to its nice reducibility, finally improving the NRA performance. Compared with TiO₂/Fe₂O₃ NSAs, TiO₂@C/Fe₂O₃ exhibited higher NRA performance with a nitrate conversion of 88.6%, ammonia selectivity of 83.4%, Faradaic efficiency of 85.3%, and ammonia yield of 0.2176 mmol h⁻¹ cm⁻². Moreover, the retention of high activity in nine cyclic experiments confirmed the outstanding stability of TiO₂@C/Fe₂O₃. Furthermore, the possible NRA reaction pathway was derived from the results of electrochemical quasi in situ electron spin resonance experiments, electrochemical in situ attenuated total reflection Fourier transform infrared measurement and online differential electrochemical mass spectrometry. This feasible strategy of introducing an HTC interlayer may open new avenues for developing novel NRA electrocatalysts.

电化学硝酸盐还原氨（NRA）被认为是一种有前途的环保和节能策略，因为它可以同时实现硝酸盐废水处理和氨合成。然而，目前该方法缺乏高效的电催化剂。本工作通过“一石二鸟”的策略，通过引入热液碳（HTC）制备了催化剂TiO ₂ @C/Fe ₂ O ₃纳米片阵列（NSAs），不仅加速了充电速度由于其良好的导电性，不仅可以促进转移，而且由于其良好的还原性，还提供了丰富的氧空位，最终提高了NRA的性能。与TiO ₂ /Fe ₂ O ₃ NSA相比，TiO ₂ @C/Fe ₂ O ₃表现出更高的NRA性能，硝酸盐转化率为88.6%，氨选择性为83.4%，法拉第效率为85.3%，氨产率为0.2176 mmol h ^-1 cm ^-2。_{此外，在九次循环实验中保持高活性证实了TiO 2} @C/Fe ₂ O ₃具有出色的稳定性。此外，根据电化学准原位电子自旋共振实验、电化学原位衰减全反射傅里叶变换红外测量和在线微分电化学质谱的结果推导了可能的NRA反应途径。这种引入 HTC 中间层的可行策略可能为开发新型 NRA 电催化剂开辟新途径。