Synergistic rare-earth yttrium single atoms and copper phosphide nanoparticles for high-selectivity ammonia electrosynthesis

Electrochemical nitrate reduction to NH 3 holds a great promise for N-upcycling in nature, while its sluggish reaction kinetics involved in both the stepwise deoxygenation and hydrogenation processes necessitates the development of bespoke catalysts with multi-site engineering. Herein, we report a hybrid catalyst composed of rare-earth (RE) yttrium (Y) single atoms and copper phosphide (Cu 3 P) nanoparticles loaded on N, P-doped carbon (Y SA -Cu 3 P/CNP) through a chelating and pyrolysis method. Owing to a synergistic contribution of Y single atoms and Cu 3 P nanoparticles, Y SA -Cu 3 P/CNP achieves an impressive NH 3 Faradaic efficiency (FE) of 92% at − 0.5 V(vs. RHE) and the highest NH 3 yield rate of 11.4 mg·h −1 ·cm −2 at − 0.6 V (vs. RHE) in an alkaline media, which surpass most of the reported electrocatalysts. The intricate reaction pathway has been explored by online differential electrochemical mass spectrometry (DEMS), and the synergistic effect between Y single atoms and Cu 3 P nanoparticles has been studied by in situ synchrotron X-ray absorption spectroscopy. Moreover, density-functional theory (DFT) calculations unveil that the high-efficiency nitrate reduction on Y SA -Cu 3 P/CNP is attributed to a reduced energy barrier of the rate-determining deoxygenation step coupled with the enhanced stabilization of active hydrogen favorable for the hydrogenation steps, thereby boosting the overall reaction rates. In addition, a prototype Zn-nitrate battery utilizing Y SA -Cu 3 P/CNP as the cathode is unveiled. This work not only elucidates the mechanism behind the enhanced catalytic performance but also paves the way for the future development of high-efficiency electrocatalysts through dual-site engineering. Graphical Abstract