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

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.