Structure-dependent iron-based metal–organic frameworks for selective CO2-to-CH4 photocatalytic reduction

Abstract

Visible-light driven reduction of carbon dioxide (CO₂) to methane (CH₄) is a challenge in the photocatalytic reaction system. Herein, two Fe-based metal–organic frameworks (MOFs) MIL-100(Fe) and MIL-101(Fe) with single-trimetallic clusters but distinct organic ligands were employed to explore the structure-dependent CO₂ conversion performance. Compared with MIL-101(Fe), MIL-100(Fe) exhibits superior catalytic activity and selectivity for CH₄ generation under visible-light irradiation via a solvent-free route. This is the first report that MIL-100(Fe) finishes the photoreduction of CO₂ into CH₄. Importantly, the plausible conversion pathways of the reaction were given by density functional theory (DFT) calculations. This work furnishes new direction for constructing MOFs to achieve CO₂-to-CH₄ conversion.