Amorphous/Crystalline Heterostructure Engineering via Electrochemical Reconstruction of Exfoliated CuCoAl Layered Double Hydroxide for Efficient and Stable Nitrate Reduction

ABSTRACT Electrochemical nitrate reduction (eNO 3 RR) mitigates environmental nitrate pollution while offering a sustainable approach for green NH 3 synthesis, but is plagued by limited electrocatalytic activity and unsatisfactory stability. Accordingly, we adopted an exfoliation‐induced in situ electrochemical deep reconstruction strategy to construct an amorphous/crystalline heterostructure using a multilayer CuCoAl layered double hydroxide (LDH) as a precursor. The characterization results illustrate that the few‐layer CuCoAl LDH underwent a deep reconstruction process to transform into a structure with co‐existing metallic Cu, crystalline Co(OH) 2 , and amorphous CoOOH. Among these, CoOOH can firmly anchor the Cu cluster to promote the transformation of NO 3 − to NO 2 − , while Co(OH) 2 mainly facilitates the subsequent hydrogenation steps. These three species act cooperatively to endow the reconstructed few‐layer LDH with extraordinary eNO 3 RR activity (99.5% Faradaic efficiency, 95.7% NH 3 selectivity, and 1.92 mol h −1 g −1 yield rate at −0.57 V vs. RHE in 0.1 m nitrate) and stability. The Zn‐NO 3 − battery assembled with FA 2 ‐CuCoAl LDH simultaneously achieved environmental remediation, energy storage, and sustainable ammonia synthesis. Thus, this study reveals the reconstruction behavior of CuCoAl LDH, demonstrates the positive effect of the exfoliation step, and provides a novel strategy for designing efficient and stable eNO 3 RR catalysts based on amorphous/crystalline heterostructure engineering.