Efficient ethane production via SnCl4 Lewis acid-enhanced CO2 electroreduction in a flow cell electrolyser

Abstract

The development of efficient and selective catalysts for electrochemical CO₂ reduction (ECR) is critical for advancing sustainable energy solutions. Here, we report a unique catalyst system based on SnCl₄ Lewis acid-modified Cu₂O, demonstrating enhanced performance in CO₂ electroreduction to ethane. The SnCl₄ modification introduces chloride ions directly onto the Cu₂O surface, creating a synergistic interaction between Sn, Cl, and Cu active sites that optimizes the electronic environment for ECR. The SnCl₄ catalyst was deposited on Cu₂O coated gas diffusion electrode (GDE) and tested in a flow cell electrolyser, integrating a Fumasep bipolar membrane and platinum (Pt) foil anode. This system achieved a peak faradaic efficiency of 34.8% for ethane production at −1.0 V vs. RHE, along with 11.3% efficiency for ethylene. Electrochemical studies revealed that the SnCl₄-modified Cu₂O exhibits low charge transfer resistance and high stability during prolonged electrolysis, achieving a total current density of 74.8 mA cm⁻² with a Tafel slope of 92.3 mV dec⁻¹ at 0.4 V overpotential. Mechanistic investigations, supported by density functional theory, Raman, XRD, and electrochemical impedance spectroscopy analyses, highlight the critical role of chloride ions in stabilizing CO intermediates and facilitating C–C bond formation, essential for C₂ product generation. Operating in a flow cell configuration, the system demonstrated high energy efficiency and selectivity, establishing the SnCl₄-modified Cu₂O (CTC) as a promising catalyst for ECR. These findings offer a scalable and economically viable pathway for renewable hydrocarbon production, paving the way for practical applications in carbon-neutral energy cycles.