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

Ethylene (C2H4), a cornerstone of the chemical industry, is produced predominantly via fossil-intensive high-temperature processes that contribute significantly to global energy consumption and CO2 emissions. Here, we report an ambient bipolar C2H4 electrosynthesis system that concurrently decarboxylates propanoic acid, a prevalent biorefinery waste, at nanoporous Pt microparticles-coated anode and reduces CO2 at W-doped CuOx-loaded cathode. Physicochemical and operando spectroscopy characterizations, along with theoretical modeling reveal that the polarized Pt-PtO2 interface formed in situ downshifts the d-band relative to Fermi level which favors the desorption of *CH2CH2 intermediate to promote selective propanoic acid decarboxylation toward C2H4. Remarkably, the resulting electrocatalyst couple delivers an unprecedented C2H4 faradaic efficiency (FEC2H4) of 118.7% and a large current density of 1000 mA cm-2, and sustains a FEC2H4 exceeding 103.4% for over 265 h at an industrial current density of 400 mA cm-2, offering a promising pathway to carbon-neutral C2H4 production from waste feedstocks.