Highly Efficient Ammonia Synthesis via Electrochemical Nitrite Reduction Using a Nitrite Reductase‐Mimicking Heterostructured Catalyst

Abstract Electrochemical nitrite reduction reaction (NO ₂ ⁻ RR) offers an energy‐efficient route for ammonia (NH ₃ ) synthesis and mitigation of nitrite wastewater pollution. However, due to the complicated reaction route involving multiple electron and proton transfers, the near 100% reaction selectivity has yet to be achieved, especially when dealing with dilute nitrite solutions. Copper‐type nitrite reductases (Cu‐NIRs) effectively catalyzes the reduction of nitrite in the nitrogen cycle in nature. Herein, as inspired by structural enzymology, a Cu‐NIRs‐mimicking heterostructured CuFe/NiFe catalyst is constructed for efficient reduction of dilute nitrite to ammonia. Mechanistic studies consisting of several advanced operando characterizations and theoretical calculations illustrate that the NiFe phase plays a dual role of hydrogen and electron donating center, while the CuFe phase serves as the active center. The bio‐inspired heterostructure well mimics the operation mechanism of Cu‐NIRs, delivers a nearly 100% Faradaic efficiency at a broad potential range above −0.5 V versus reversible hydrogen electrode, and reaches a peak NH ₃ yield rate of 45.61 mg h ⁻¹ mg ⁻¹ . This work highlights the biomimetic strategy for catalyst design, paving the way for their rational application in various electrocatalytic field.