Highly Efficient Synthesis of α-Amino Acids via Electrocatalytic C-N Coupling Reaction Over an Atomically Dispersed Iron Loaded Defective TiO.

The synthesis of α-amino acids via the electrocatalytic C-N coupling attracted extensive attention owing to the mild reaction conditions, controllable reaction parameters, and atom economy. However, the α-amino acid yield remains unsatisfying. Herein, the efficient electrocatalytic synthesis of α-amino acids is achieved with an atomically dispersed Fe loaded defective TiO monolithic electrocatalyst (Fe-TiO/Ti). The desired electrocatalyst composition for the hydrogenation of oxime is screened. The prepared Fe-TiO/Ti exhibited a high glyoxylic acid conversion of ≈100% and a glycine selectivity of 80.2%. The electrochemical experiments and theoretical calculations demonstrated that atomically dispersed Fe (Fe) sites and oxygen vacancies (OVs) enhanced the adsorption of glyoxylic acid (GA), glyoxylic oxime (GO), and nitrate (NO ). Fe sites further promote the step of HNO → HNOH in the conversion of NO to hydroxylamine (NHOH) and the step of NH-CH-COOH → NH-CH-COOH in the reduction of GO to glycine. The coupling pathway and the critical intermediate are revealed by synchrotron radiation Fourier transform infrared (SR-FTIR) spectroscopy and differential electrochemical mass spectrometry (DEMS). Additionally, six other α-amino acids are successfully synthesized by the Fe-TiO/Ti, showcasing its versatility in the electrosynthesis of α-amino acids. This work provides an efficient electrocatalyst for the C-N coupling synthesis of α-amino acids.