Bipolar ethylene electrosynthesis from CO2 and biowaste acid with total faradaic efficiency over 118%

Ethylene (C 2 H 4 ), a cornerstone of the chemical industry, is produced predominantly via fossil-intensive high-temperature processes that contribute significantly to global energy consumption and CO 2 emissions. Here, we report an ambient bipolar C 2 H 4 electrosynthesis system that concurrently decarboxylates propanoic acid, a prevalent biorefinery waste, at nanoporous Pt microparticles-coated anode and reduces CO 2 at W-doped CuO x -loaded cathode. Physicochemical and operando spectroscopy characterizations, along with theoretical modeling reveal that the polarized Pt-PtO 2 interface formed in situ downshifts the d-band relative to Fermi level which favors the desorption of *CH 2 CH 2 intermediate to promote selective propanoic acid decarboxylation toward C 2 H 4 . Remarkably, the resulting electrocatalyst couple delivers an unprecedented C 2 H 4 faradaic efficiency (FE C2H4 ) of 118.7% and a large current density of 1000 mA cm −2 , and sustains a FE C2H4 exceeding 103.4% for over 265 h at an industrial current density of 400 mA cm −2 , offering a promising pathway to carbon-neutral C 2 H 4 production from waste feedstocks.