Electrosynthesis of polymer-grade ethylene via acetylene semihydrogenation over undercoordinated Cu nanodots.

The removal of acetylene impurities remains important yet challenging to the ethylene downstream industry. Current thermocatalytic semihydrogenation processes require high temperature and excess hydrogen to guarantee complete acetylene conversion. For this reason, renewable electricity-based electrocatalytic semihydrogenation of acetylene over Cu-based catalysts is an attractive route compared to the energy-intensive thermocatalytic processes. However, active Cu electrocatalysts still face competition from side reactions and often require high overpotentials. Here, we present an undercoordinated Cu nanodots catalyst with an onset potential of -0.15 V versus reversible hydrogen electrode that can exclusively convert C 2 H 2 to C 2 H 4 with a maximum Faradaic efficiency of ~95.9% and high intrinsic activity in excess of -450 mA cm -2 under pure C 2 H 2 flow. Subsequently, we successfully demonstrate simulated crude ethylene purification, continuously producing polymer-grade C 2 H 4 with <1 ppm C 2 H 2 for 130 h at a space velocity of 1.35 × 10 5  ml g cat -1 h -1 . Theoretical calculations and in situ spectroscopies reveal a lower energy barrier for acetylene semihydrogenation over undercoordinated Cu sites than nondefective Cu surface, resulting in the excellent C 2 H 2 -to-C 2 H 4 catalytic activity of Cu nanodots.