Novel layer-to-layer charge transfer in an anion-pillared metal-organic framework for efficient CO₂ photoreduction to CH₄

The highly selective photoreduction of CO₂ to CH₄ is hindered by the sluggish eight-electron transfer process and rapid recombination of charge carriers. Herein, an anion-pillared metal–organic framework photocatalyst, CuSiF₆-TPPY, is judiciously constructed for the highly selective photoreduction of CO₂ to CH₄. The polar SiF₆²⁻ pillars significantly enhance the CO₂ adsorption capacity to 96.56 cm³ g⁻¹. Furthermore, the incorporation of SiF₆²⁻ pillars separates the HOMO and LUMO energy levels in distinct MOF layers, leading to a lower energy barrier for *CHO generation and a higher energy barrier for CO desorption. As a result, CuSiF₆-TPPY delivers a CH₄ generation rate of 13.84 μmol g⁻¹ h⁻¹ with a high selectivity of 88.78 %, 4-times higher than TPPY ligands. Moreover, in-situ IR spectra and computational simulations further confirm the photoreduction pathways.