Synergistic Dual‐Atom Cu Nanozyme for Efficient Electrocatalytic Nitrate Reduction to Ammonia

ABSTRACT The electrocatalytic nitrate reduction reaction (NO ₃ RR) to ammonia (NH ₃ ) represents a promising strategy for sustainable NH ₃ synthesis while mitigating nitrate contamination. However, challenges remain for sluggish kinetics and poor selectivity due to inefficient nitrite (NO ₂ ⁻ ) activation and inadequate generation/utilization of reactive hydrogen species (H*). To address these issues, we design a dual‐atom copper nanozyme anchored on hollow carbon spheres (Cu ₂ ‐S ₁ N ₄ /HCS) by mimicking the enzymatic architecture of copper‐containing nitrite reductases (Cu‐NIRs). Experimental and theoretical investigations reveal that the Cu‐S ₁ N ₂ site facilitates water dissociation to generate H*, which subsequently spills over to the Cu‐N ₃ site. Meanwhile, the electrons are transferred from Cu‐S ₁ N ₂ to Cu‐N ₃ site induced by regulation of coordination environments, resulting in stabilization of the key NO ₃ RR intermediates by low‐valent Cu at the Cu‐N ₃ site. In this process, the Cu‐N ₃ site serves as the catalytic center for inter‐site coupling of H*/e ⁻ transfer‐mediated deoxygenation and hydrogenation of NO ₃ ⁻ to NH ₃ . The resulting Cu ₂ ‐S ₁ N ₄ /HCS dual‐atom nanozyme delivers a remarkable NO ₃ ⁻ ‐to‐NH ₃ Faradaic efficiency (FE, 93.1%) and a high NH ₃ yield rate (11.8 mg h ⁻¹ cm ⁻² ) at −0.6 V vs. reversible hydrogen electrode (RHE). This work demonstrates a bioinspired strategy that mimics natural Cu‐NIRs, which offers an efficient and sustainable route for ammonia production from wastewater.