Modulating Surface‐Active Hydrogen for Facilitating Nitrate‐to‐Ammonia Electroreduction on Layered Double Hydroxides Nanosheets
Bin Liu, Yuan Wang, Huiming Wen, Yuchen Wang, Heng Liu, Bo Da, Ke Li, Hao Luo, Hao Li, Kai Yan
Abstract
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.