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

Abstract 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.