Solar-Driven Conversion of CO 2 to C 2 Products by the 3d Transition Metal Intercalates of Layered Lead Iodides.

Photocatalytic CO 2 reduction to high-value-added C 2+ products presents significant challenges, which is attributed to the slow kinetics of multi-e - CO 2 photoreduction and the high thermodynamic barrier for C-C coupling. Incorporating redox-active Co 2+ /Ni 2+ cations into lead halide photocatalysts has high potentials to improve carrier transport and introduce charge polarized bimetallic sites, addressing the kinetic and thermodynamic issues, respectively. In this study, a coordination-driven synthetic strategy is developed to introduce 3d transition metals into the interlamellar region of layered organolead iodides with atomic precision. The resultant bimetallic halide hybrids exhibit selective photoreduction of CO 2 to C 2 H 5 OH using H 2 O vapor at the evolution rates of 24.9-31.4 µmol g -1  h -1 and high selectivity of 89.5-93.6%, while pristine layered lead iodide yields only C 1 products. Band structure calculations and photoluminescence studies indicate that the interlayer Co 2+ /Ni 2+ species greatly contribute to the frontier orbitals and enhance exciton dissociation into free carriers, facilitating carrier transport between adjacent lead iodide layers. In addition, Bader charge distribution calculations and in situ experimental spectroscopic studies reveal that the asymmetric Ni-O-Pb bimetallic catalytic sites exhibit intrinsic charge polarization, promoting C-C coupling and leading to the formation of the key *OC-CHO intermediate.