Photothermal‐Responsive Artificial Enzyme Assembly Engineering for Near‐Unity Nitrate‐to‐Ammonia Electrocatalysis

Natural enzymatic nitrate (NO 3 ‒ ) conversion exhibits inherent limitations under anthropogenic disturbances. Herein, we proposed an artificial enzyme assembly engineering that integrated a photothermal module with a biomimetic catalytic framework, aiming to transcend the functionality of natural enzyme. The integrated catalyst (Cu x /Cu 1 ‐NC) features coexisting Cu clusters and single atoms anchored on a nitrogen‐doped carbon substrate. In a photo‐electro system, the catalyst exhibited nearly 100% ammonia (NH 3 ) selectivity, with an NH 3 yield increased by 23.1 times compared to the unmodified single‐atom catalyst (Cu 1 ‐C). Mechanistic studies at the atomic and molecular levels reveal that, Cu clusters and Cu single atoms successfully mimic T1Cu and T2Cu in copper‐containing nitrite reductase (Cu‐NIR), supplying electrons and protons during NO 3 ‒ reduction process. Nitrogen‐doped carbon substrate possesses an asymmetric electron distribution function akin to that of amino acid residues in enzymes, constructing an efficient *H transfer network. In situ detection and physical modeling demonstrated that, the plasmonic resonance of Cu clusters generates an electromagnetic field intensity of 44.8 on a log 10 (|E| 2 ) scale at the interatomic gaps and produces an interfacial thermal field of 80.1°C within 1 min under irradiation of 400 mW·cm −2 , thereby promoting reactivity. This work offers a state‐of‐the‐art photothermal‐responsive artificial enzyme assembly strategy for directed NO 3 ‒ conversion.