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 PbBiCsOCl, and successfully fabricate a new 2D ultrathin bimetallic oxyhalide PbBiOCl. The unlocked larger surface area, rich bimetallic active sites, and faster carrier dynamics within PbBiOCl layers significantly enhance the photocatalytic efficiency for atmospheric CO 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 CO reduction, which sheds light on further constructing other ultrathin 2D catalysts for environmental and energy applications from similar complicate structure matrixes.