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. Traditional thermocatalytic production of ethylene is hindered by high energy penalty and carbon footprint. Here, the authors report an ambient bipolar ethylene electrosynthesis system by coupling oxidative decarboxylation of propanoic acid biowaste with CO2 electroreduction.