Monti, N.B.D.; El-Nagar, G.A.; Fontana, M.; Di Costola, F.; Gupta, S.; Mayer, M.T.; Pirri, C.F.; Zeng, J.: Insights into the stability of copper gas diffusion electrodes for carbon dioxide reduction at high reaction rates. Materials Today Sustainability 30 (2025), p. 101124/1-10
10.1016/j.mtsust.2025.101124
Open Access Version
Abstract:
Electrosynthesis of value-added chemicals from CO2 offers a sustainable solution to climate change, renewable energy use, and raw material shortages. This study examines the high-rate production of ethylene (C2H4) and ethanol (CH3CH2OH) through CO2 reduction reaction on copper (Cu) gas diffusion electrodes (GDEs) made by sputtering deposition. The catalyst layer thickness of the GDEs, adjusted by deposition time, significantly affects the electrode stability. During testing, a selectivity shift is observed, where C2H4 and CH3CH2OH selectivity decreases, while CH4 and H2 selectivity increases. However, an alternating operation by interrupting and restarting the polarization fully restores the C2H4 and CH3CH2OH selectivity. Operando X-ray absorption spectroscopy with online product analysis reveals that at constant potentials, the dominant oxidized Cu species gradually reduces to metallic Cu, along with a decline in C2H4 selectivity. Under alternating operation, some oxidized Cu species remains, and the C2H4 selectivity is also preserved. This outcome suggests a close link between cationic Cu species and C2H4 production, offering insights into stabilizing these species for prolonged C2H4 production.