Cerium doped zeolitic imidazolate framework (Ce-ZIF-8) catalysts for efficient CO₂ electroreduction to syngas

Electrochemical CO₂ reduction reaction (eCO₂RR) offers a promising route for converting greenhouse gases into value-added chemicals and fuels. Among different materials, Zeolitic imidazolate frameworks (ZIF-8) have attracted attention as potential catalysts due to their high surface area, tunable structure, and chemical stability; however, their limited activity and selectivity remain challenges. In this work, a rare-earth, abundant, and environmentally benign element, cerium (Ce), is incorporated into ZIF-8 (Ce-ZIF-8) via a facile synthesis route at different molar ratio (Ce/(Ce + Zn)) to enhance catalytic performance toward syngas (CO/H₂) production. Different characterizations including XRD, SEM, EDX, TEM, BET, and XPS revealed a strong relationship between catalyst structure, composition and electrochemical performance, with 20% Ce-ZIF-8 identified as the optimal catalyst. Electrochemical measurements showed improved activity for CO₂ reduction to CO/H₂ in H-cell and flow cell configurations. In H-cell configuration, 20% Ce-ZIF-8 exhibits improved current density and enhanced CO₂ reduction activity compared to pristine ZIF-8. Under flow-cell operational conditions, the catalyst achieves a Faradaic efficiency of approximately 64% for CO and ~29% for H₂ at −0.7 V vs reversible hydrogen electrode (RHE), demonstrating efficient and tunable CO/H₂ generation under practical conditions. These results highlight the significant impact of controlling Ce incorporation on enhancing the catalytic performance of ZIF-8. The developed Ce-ZIF-8 catalyst provides a cost-effective and sustainable alternative to noble-metal-based systems, offering a promising pathway for scalable CO₂ conversion and renewable energy applications.