Synergistic Modulation of Intermediate Adsorption and Active Hydrogen Supply Enable Pulsed Nitrate‐to‐Hydroxylamine Electroreduction with Nearly 100% Faradaic Efficiency

Electrochemical hydroxylamine (NH2OH) synthesis from NOx under ambient conditions presents a sustainable alternative to energy‐intensive industrial methods, but its selectivity remains limited by unbalanced active hydrogen (H*) supply and intermediate adsorption. Herein, we develop boron‐doped amorphous Bi metallene arrays for efficient nitrate‐to‐NH2OH electroreduction. In situ spectroscopy and theoretical calculations reveal that the amorphous structure and B‐induced p‐sp orbital hybridization modulate the electronic structure, optimizing intermediate adsorption while enhancing H* generation. These synergistic effects collectively reduce the energy barrier of the potential‐determining step, significantly improving catalytic activity and selectivity. The catalyst achieves an NH₂OH Faradaic efficiency (FE) of 85.3% at −0.4 V vs. reversible hydrogen electrode (RHE). By employing a pulsed potential strategy, the FE further increases to nearly 100%, surpassing most reported counterparts. This work not only proposes a novel catalyst design leveraging amorphous engineering and orbital hybridization but also demonstrates the efficacy of pulsed electrolysis in steering reaction pathways for electrosynthesis.