Unlocking bimetallic active sites via a desalination strategy for photocatalytic reduction of atmospheric carbon dioxide

Ultrathin two-dimensional (2D) metal oxyhalides exhibit outstanding photocatalytic properties with unique electronic and interfacial structures. Compared with monometallic oxyhalides, bimetallic oxyhalides are less explored. In this work, we have developed a novel top-down wet-chemistry desalination approach to remove the alkali-halide salt layer within the complicated precursor bulk structural matrix Pb_0.6Bi_1.4Cs_0.6O₂Cl₂, and successfully fabricate a new 2D ultrathin bimetallic oxyhalide Pb_0.6Bi_1.4O₂Cl_1.4. The unlocked larger surface area, rich bimetallic active sites, and faster carrier dynamics within Pb_0.6Bi_1.4O₂Cl_1.4 layers significantly enhance the photocatalytic efficiency for atmospheric CO₂ reduction. It outperforms the corresponding parental matrix phase and other state-of-the-art bismuth-based monometallic oxyhalides photocatalysts. This work reports a top-down desalination strategy to engineering ultrathin bimetallic 2D material for photocatalytic atmospheric CO₂ reduction, which sheds light on further constructing other ultrathin 2D catalysts for environmental and energy applications from similar complicate structure matrixes.