Synthesis of amino acids by electrocatalytic reduction of CO2 on chiral Cu surfaces

CO2 reduction and fixation products, ranging from small molecules to biomolecules, are highly diverse in natural systems. Although 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 synthesis from CO2 and NH3, using chiral Cu films (CCFs) as electrodes. Electron microscopy and theoretical calculations suggested that chiral kink sites can possibly be formed on the surface of CCFs fabricated through 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 H2CO–CO∗ is the stereo-determining step in the Ser formation pathway. The chiral kink sites were speculated to be restricting the configuration changes of C3+ intermediates to involve a thermodynamically and kinetically favorable formation of enantiomeric Ser.