Modulating Surface‐Active Hydrogen for Facilitating Nitrate‐to‐Ammonia Electroreduction on Layered Double Hydroxides Nanosheets

Abstract Electrocatalytic nitrate (NO 3 − ) reduction reaction (NitRR) to valuable ammonia (NH 3 ) presents a promising alternative strategy to the conventional Haber‐Bosch process, yet suffers from low Faradaic efficiency (FE) and limited NH 3 yield due to the sluggish multi‐electron/proton transfer steps involved. Here, NiCuFe‐layered double hydroxides (NiCuFe‐LDHs) nanosheets with abundant metal Ni and Cu sites are synthesized for facilitating NO 3 − ‐to‐NH 3 electroreduction with a large NH 3 yield of 1.64 mmol h −1 cm −2 , NH 3 FE of 94.8% and high stability for 15 cycles. Computational and theoretical analysis reveals the NitRR pathway and elucidates that the Cu and Ni sites act as the primary center for NO 3 − adsorption and activation. Meanwhile, the Ni site effectively modulates the adsorption and dissociation of H 2 O to provide sufficient H * , thus enhancing the NitRR activity of NiCuFe‐LDHs nanosheets. Consequently, the Zn‐NO 3 − battery utilizing NiCuFe‐LDHs nanosheets as the cathode delivers a high FE of 85.8%, a large NH 3 yield of 1.63 mmol h −1 cm −2 , and a remarkable power density of 12.4 mW cm −2 , outperforming most previous reports, which enable the simultaneous NO 3 − pollutants removal, NH 3 production, and electricity output. This work offers a promising strategy for designing and synthesizing efficient electrocatalysts for NO 3 − removal and value‐added NH 3 production.