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

Natural enzymatic nitrate (NO₃ ^‒) 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/Cu₁-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 (NH₃) selectivity, with an NH₃ yield increased by 23.1 times compared to the unmodified single-atom catalyst (Cu₁-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 NO₃ ^‒ 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 log₁₀(|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 NO₃ ^‒ conversion.