Gaseous Ethanol Generation from an Air Pollutant Gaseous Acetaldehyde Directly on a Wetted CuMg Electrode Interface

Acetaldehyde is a representative volatile organic compound (VOC) predominantly emitted in the gas phase, with over 92.6% originating from industrial sources. Conventional treatment relies on oxidative mineralization to CO₂, offering limited potential for value-added product generation. In this study, we demonstrate an electrochemical system utilizing a poly(vinyl alcohol)–sodium polyphosphate–magnesium (PVA–SPP–Mg) gel-polymer-electrolyte (GPE) that facilitates the direct conversion of gaseous acetaldehyde into gaseous ethanol at a wetted copper–magnesium (CuMg) alloy cathode interface. Magnesium ion incorporation improved ionic conductivity (0.061 S cm^–1in the liquid phase) and structural stability, maintaining performance for 70 h under gas flow with 48% swelling. Single-pass experiments achieved 85% acetaldehyde removal, and ethanol formation was confirmed by an in-line Fourier transform infrared (FTIR) analysis. A poly(tetrafluoroethylene) (PTFE) surface coating enhanced ethanol desorption, ensuring 80% carbon recovery. Under continuous operation (100 ppmv acetaldehyde, −3.75 mA cm^–2, 24 h), the system exhibited stable performance without liquid leakage. This platform enables direct gas–solid conversion of acetaldehyde to ethanol and offers a sustainable and scalable alternative to VOC treatment in industrial environments.