Upgrading waste NO_x into amino acids via electrocatalysis on Co nanoparticles encapsulated in hollow carbon nanofibers

Electrocatalytic conversion of waste nitrogen oxide (NO_x) into value-added nitrogenous chemicals, especially amino acid, is an emerging strategy to alleviate NO_x pollution. However, this process suffers from the coexistence of multiple competitive reactions leading to complex product distribution and low efficiency, and thus the rational design and modulation of efficient catalysts remains a formidable challenge. Herein, well-designed Co nanoparticles encapsulated in hollow carbon nanofiber (Co-HCNF) were constructed to promote the amino acid electrosynthesis via dealing waste NO_x coupling with biomass-derived keto acids. Ascribed to the rapid reactant diffusion, electron transport and efficient contact with abundant accessible Co catalytic sites stemmed from the unique hollow nanotubular structure, Co-HCNF manifested impressive glycine synthesis performance in one-pot adopting NO as the nitrogen source with Faradaic efficiency (FE) of 41.7% and a corresponding yield rate of 222.3 µmol h⁻¹ as well as 120 h robust stability. Interestingly, it also demonstrates an excellent performance with the FE of 42.8% for NO₃⁻ solution as the nitrogen source. Specially, this strategy displays a broad universality for the synthesis of other amino acids. This work not only highlights the importance of hollow-structuring electrocatalyst towards upgrading wasted NO_x species into amino acids, but also promotes the further development of electrosynthetic systems for high-valued N-containing organic chemicals.