Two dimensional PbMoO4: A photocatalytic material derived from a naturally non-layered crystal

Metal molybdates, such as lead molybdate (PbMoO4), are wide bandgap crystals with favourable photophysical and photocatalytic properties and also high stability. If these crystals are synthesized in two dimensional (2D) morphologies, they can offer the needed large surface-area for photo-reactions. However, this category of materials does not constitute natural stratified crystals, and hence cannot be readily formed into 2D sheets using conventional methods. Here we present a two-step synthesis approach. First, we exfoliate stratified alpha-MoO3 into alpha-MoO3-x. Subsequently, these defect rich 2D alpha-MoO3-x nanosheets are transformed into stable 2D PbMoO4 nanosheets by dipping-pulling. We show that the transformed 2D PbMoO4 display trap states within its bandgap, allowing its efficient performance as a photocatalyst under the visible light condition. The presented method in this work can be extended to establish a variety of highly stable defect rich 2D metal molybdates, which are otherwise challenging to achieve, for visible light region photo-reactions.