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.