Renewable-energy-driven nitrate (NO₃^-) electroreduction to ammonia (NH₃) (NERA) has been an attractive technology for decarbonizing NH₃ production and wastewater treatment. Improving NERA efficiency requires electrocatalysts that are earth-abundant and show fantastic performance. Here we report a semiempirical activity descriptor of e_g occupancy (of surface B-site cations) for identifying inexpensive perovskite oxides with extremely high efficacy toward NERA. We establish the descriptor by systematic investigations of more than 10 perovskite oxides. These investigations demonstrate that their intrinsic NERA activities display a volcano-shaped dependence on e_g occupancy and the optimized intrinsic activities are accessible at near-1 e_g occupancies. This could plausibly be attributed to the favorable overlaps between surface adsorbates and vertically-oriented e_g orbitals. More importantly, utilizing this descriptor, we predict a highly active, selective, and durable NERA electrocatalyst with a composition of Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3−δ (BSCF). Because of its close-to-1 e_g occupancy (i.e. ∼ 1.2), the BSCF features a superior NH₃ production rate of \(0.12\,\,{\rm{g}} \cdot {{\rm{h}}^{ - 1}} \cdot {\rm{m}}{{\rm{g}}_{{\rm{cat}}{\rm{.}}}}^{ - 1}\) (Faradaic efficiency of 97.8%) that is at top of the volcano plot, and substantially outperforms most NERA electrocatalysts reported in literature.

可再生能源驱动的硝酸盐（NO ₃ ^-）电还原为氨（NH ₃）（NERA）一直是NH ₃生产和废水处理脱碳的一项有吸引力的技术。提高 NERA 效率需要地球储量丰富且性能出色的电催化剂。在这里，我们报告了一种半经验活性描述符_（表面 B 位阳离子的占据），用于识别对 NERA 具有极高功效的廉价钙钛矿氧化物。我们通过对 10 多种钙钛矿氧化物的系统研究建立了描述符。_{这些研究表明，它们的内在 NERA 活动表现出对 e g}占用率的火山形依赖性，并且在接近 1 e _g占用率时可以获得优化的内在活动。这可能归因于表面吸附物和垂直取向（例如轨道_）之间的有利重叠。更重要的是，利用这个描述符，我们预测了一种高活性、选择性和耐用的NERA电催化剂，其成分为Ba _0.5 Sr _0.5 Co _0.8 Fe _0.2 O _{3− δ} (BSCF)。由于其接近 1 e _{g 的}占有率（即 ∼ 1.2），BSCF 具有优异的 NH ₃生产率，为\(0.12\,\,{\rm{g}} \cdot {{\rm{h} }^{ - 1}} \cdot {\rm{m}}{{\rm{g}}_{{\rm{cat}}{\rm{.}}}}^{ - 1}\) (法拉第效率为 97.8%），位于火山图的顶部，并且大大优于文献中报道的大多数 NERA 电催化剂。