关键词: 二氧化碳电还原, 膜电极, 电解池, 稳定性

Abstract:

Electro-catalytic reduction is an efficient way to achieve resourcable transformation of CO₂, which is one of the important techniques to solve the global environmental problems originated from excessive CO₂ emission. In this study, a membrane electrode assembly(MEA) type CO₂ electro-reduction electrolytic cell was constucted, which enables CO₂ feeding and real-time KHCO₃ aqueous updating on both sides of the cathode gas diffusion electrode (GDE). By means of the electrolytic cell, effects of KHCO₃ concentration and updating inside the liquid electrolytic chamber on CO₂ electro-reduction activity, production distribution and stability were investigated. The experimental results suggested that the KHCO₃ concentration exerted strong influence on the cell voltage rather than the production distribution for the current densities lower than 5 mA·cm^-2. The performance of MEA type CO₂ electro-reduction cell decayed in both “reversible” and “irreversible” ways. Catalysts leaking at the GDE/liquid electrolyte interface might be respossible for the cell “irreversible” decay. Meanwhile, th leakage of KHCO₃ aqueous electrolyte arose from gas accumulation in the liquid electrolytic chamber contributed to the “reversible” degradation, which could be recovered effectively by updating the KHCO₃ aqueous electrolyte.

Key words: CO₂ electro-reduction, membrane electrode assembly, electrolytic cell, stability