Electrosynthesis of Nitriles from Nitrate and Aldehyde via C≡N Bond Construction

Electrocatalytic nitrate reduction offers a promising approach to synthesizing valuable organic nitrogen compounds via C-N coupling, serving as a pivotal solution to the pressing nitrate pollution issue. While significant progress has been made in electrosynthesizing C-N and C═N compounds, the electrosynthesis of nitriles with C≡N bond formation via NO_x as nitrogen sources remains challenging. Herein, we introduce a novel method for efficient synthesizing nitriles through electrocatalytic coupling of nitrate ions (NO₃^-) with aldehydes under ambient conditions, employing ZnO/Sn/SnO₂ as the electrocatalyst. In situ spectroscopic characterization and theoretical calculations demonstrated that the adsorption and accumulation of *NH₂OH and *RCHO on the catalyst plays a central role in the efficient reaction. The key C-N bond-forming step is found to be the formation of hydroxylamine from nitrate reduction and its subsequent condensation with *RCHO. The C-N coupling strategy can be applied to the synthesis of fatty nitrile and (hetero)aromatic nitrile compounds. This study opens the way for nitriles electrosynthesis from nitrogen wastes, which could contribute to utilization of nitrogen resources.