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

Abstract

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.