Modulating Inorganic Dimensionality of Ultrastable Lead Halide Coordination Polymers for Photocatalytic CO2 Reduction to Ethanol

Abstract

AbstractLead halide hybrids have shown great potentials in CO2 photoreduction, but challenging to afford C2+ reduced products, especially using H2O as the reductant. This is largely due to the trade‐off problem between instability of the benchmark 3D structures and low carrier mobility of quasi‐2D analogues. Herein, the lead halide dimensionality of robust coordination polymers (CP) was modulated by organic ligands differing in a single‐atom change (NH vs. CH2), in which the NH groups coordinate with interlamellar [PbI2] clusters to achieve the important 2D→3D transition. This first CP based on 3D cationic lead iodide sublattice possesses both high aqueous stability and a low exciton binding energy of 25 meV that is on the level of ambient thermal energy, achieving artificial photosynthesis of C2H5OH. Photophysical studies combined with theoretical calculations suggest the bridging [PbI2] clusters in the 3D structure not only results in enhanced carrier transport, but also promotes the intrinsic charge polarization to facilitate the C−C coupling. With trace loading of Rh cocatalyst, the apparent quantum efficiency of the 3D CP reaches 1.4 % at 400 nm with a high C2H5OH selectivity of 89.4 % (product basis), which presents one of the best photocatalysts for C2 products to date.