Constructing Cu 3d-O 2p-La 4f Gradient Orbitals for Efficient High-Current-Density Nitrate-to-Ammonia Electrosynthesis

Nitrate, as a core component of water pollution, poses a severe threat to the ecological environment and human health. Electrochemical ammonia synthesis via nitrate reduction (NO3RR) is a highly promising sustainable technology, yet the simultaneous achievement of high activity and high selectivity remains a critical challenge in this field. Conventional Cu-based catalysts suffer from insufficient intrinsic activity and sluggish reaction kinetics. Moreover, the Cuδ+ active sites are prone to valence evolution and structural reconstruction during electrocatalysis, making it difficult to meet the demands of long-term industrial-scale operation. To break through the aforementioned bottlenecks, this study proposes a rare-earth-regulated electronic structure engineering strategy. By constructing a Cu 3d–O 2p–La 4f gradient orbital coupling system, the surface chemisorption behavior of transition metals is precisely optimized, and the electron transfer pathway is efficiently modulated. The introduction of La not only strengthens electron delocalization and transport through the gradient orbital channel to enhance the adsorption and activation capability of NO3−, but also stabilizes the Cuδ+ active sites via its unique 4f electronic structure, optimizes the adsorption energy of key intermediates, and synergistically boosts the catalytic performance. Experimental results demonstrate that the optimized La0.02-CuOx electrode exhibits no obvious performance degradation after continuous operation for 30 h at a large current density of 2.5 A cm−2, delivering an ammonia yield of 186.99 mg·h−1·cm−2 and a Faradaic efficiency of 94.39%. This rare-earth orbital coupling strategy provides a new research insight for the rational design of highly stable Cu-based NO3RR catalysts.