Green Synthesis of MOF‐Based Materials for Electrochemical Reduction of Carbon Dioxide

Porous ZIF-8 and ZIF-67 were synthesized via a green steam-assisted dry-gel technique and investigated as potential catalysts for CO₂ electroreduction. The synthesis conditions are found to significantly influence the growth of these metal-organic frameworks (MOFs). Notably, the water content employed during synthesis plays a crucial role in shaping the morphological properties of ZIF-8. Specifically, a moderate water content results in the formation of uniform ZIF-8 with a size distribution ranging from 240-440 nm. During CO₂ electroreduction, these morphological properties exert substantial effects on the selectivity for CO formation, thereby facilitating the production of syngas with adjustable CO: H₂ ratios. This feature holds promise for the widespread adoption of syngas as a clean alternative to fossil fuels, offering potential benefits for electricity generation and liquid fuel production. Despite sharing similar structural properties with ZIF-8, ZIF-67 exhibits distinct performance characterized by its limited selectivity for CO₂ electroreduction. This discrepancy is attributed to the different metal centers of the two MOFs, resulting in the distinct activation of CO₂ and H₂O molecules and their further reduction. This finding highlights the critical role of metal centers in MOF-based materials for electrocatalysis application.