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 Pb0.6Bi1.4Cs0.6O2Cl2, and successfully fabricate a new 2D ultrathin bimetallic oxyhalide Pb0.6Bi1.4O2Cl1.4. The unlocked larger surface area, rich bimetallic active sites, and faster carrier dynamics within Pb0.6Bi1.4O2Cl1.4 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.