Modulating Inorganic Dimensionality of Ultrastable Lead Halide Coordination Polymers for Photocatalytic CO 2 Reduction to Ethanol.

Lead halide hybrids have shown great potentials in CO 2 photoreduction, but challenging to afford C 2+ reduced products, especially using H 2 O 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. CH 2 ), in which the NH groups coordinate with interlamellar [PbI 2 ] 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 C 2 H 5 OH. Photophysical studies combined with theoretical calculations suggest the bridging [PbI 2 ] 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 C 2 H 5 OH selectivity of 89.4 % (product basis), which presents one of the best photocatalysts for C 2 products to date.