Modulating Single-Atom Palladium Sites with Copper for Enhanced Ambient Ammonia Electrosynthesis

The electrochemical reduction of N-2 to NH3 is emerging as a promising alternative for sustainable and distributed production of NH3. However, the development has been impeded by difficulties in N-2 adsorption, protonation of *NN, and inhibition of competing hydrogen evolution. To address the issues, we design a catalyst with diatomic Pd-Cu sites on N-doped carbon by modulation of single-atom Pd sites with Cu. The introduction of Cu not only shifts the partial density of states of Pd toward the Fermi level but also promotes the d-2 pi* coupling between Pd and adsorbed N-2, leading to enhanced chemisorption and activated protonation of N-2, and suppressed hydrogen evolution. As a result, the catalyst achieves a high Faradaic efficiency of 24.8 +/- 0.8 % and a desirable NH3 yield rate of 69.2 +/- 2.5 mu g h(-1) mg(cat.)(-1), far outperforming the individual single-atom Pd catalyst. This work paves a pathway of engineering single-atom-based electrocatalysts for enhanced ammonia electrosynthesis.