Developing efficient electrocatalysts for selective nitrate contamination reduction into value-added ammonia is significant. Here, heterostructured Co/CoO nanosheet arrays (Co/CoO NSAs) exhibited excellent Faradaic efficiency (93.8%) and selectivity (91.2%) for nitrate electroreduction to ammonia, greatly outperforming Co NSAs. ¹⁵N isotope labeling experiments and ¹H nuclear magnetic resonance (NMR) quantitative testing methods confirmed the origin of the produced ammonia. Electrochemical in situ Fourier transform infrared (FTIR) spectroscopy, online differential electrochemical mass spectrometry (DEMS) data and density functional theory (DFT) results revealed that the superior performances arose from the electron deficiency of Co induced by the rectifying Schottky contact in the Co/CoO heterostructures. The electron transfer from Co to CoO at the interface could not only suppress the competitive hydrogen evolution reaction, but also increase energy barriers for by-products, thus leading to high Faradaic efficiency and selectivity of ammonia.

开发有效的电催化剂以选择性地将硝酸盐污染减少为增值的氨具有重要意义。在这里，异质结构的Co / CoO纳米片阵列（Co / CoO NSA）表现出出色的法拉第效率（93.8％）和硝酸盐电还原成氨的选择性（91.2％），大大优于Co NSA。¹⁵ N同位素标记实验和¹ H核磁共振（NMR）定量测试方法证实了所产生氨的来源。电化学原位傅里叶变换红外（FTIR）光谱，在线差分电化学质谱（DEMS）数据和密度泛函理论（DFT）结果表明，优异的性能归因于Co / CoO异质结构中的整流肖特基接触引起的Co电子缺乏。电子在界面处从Co转移到CoO不仅可以抑制竞争性的析氢反应，而且还可以增加副产物的能垒，从而提高了法拉第效率和氨的选择性。