Synthesis of Amino Acids by Electrocatalytic Reduction of CO2 on Chiral Cu Surfaces

Abstract CO2 reduction and fixation products ranging from small molecules to biomolecules, are highly diverse in natural systems. Athough various multicarbon products of CO2 reduction were artificially obtained, the C3+ products with various functional groups (e.g., C-N and C=O bonds), especially biomolecules, have never been reported. Herein, we synthesized C3+ amino acids via electrocatalytic reduction from CO2 and NH3 using chiral Cu films (CCFs) as electrodes. Electron microscopy and theoretical calculations suggested that chiral kink sites Cu(653) is the most likely formed on the surface of CCFs fabricated by electrodeposition in the presence of Histidine (His). Serine (Ser), with an enantiomeric excess (ee) greater than 90% is the main component of various amino acids. Experimental and computational data showed that the 3-hydropyruvic acid formation from OCH2CO* is the stereo-determining step in the Ser formation pathway. The Cu(653) was speculated to be restricting the configuration changes of C3+ intermediates to involve a thermodynamically and kinetically favourable formation of enantiomeric Ser.