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.