Photocatalytic activity of 2D nanosheets of ferroelectric Dion-Jacobson compounds

Dion-Jacobson compounds have a layered perovskite structure, and a small number of them have been identified as being ferroelectric. Here, RbBiNb2O7 powders are made by conventional solid-state synthesis. The relatively large Rb ion produces an interlayer within the structure with a large spacing and weak bonding. This work shows for the first time that a polar layered perovskite can be exfoliated into 2D nanosheets using a facile and scalable method, namely liquid-phase sonication. With both 2D materials and ferroelectrics being of interest for photocatalysis, the photocatalytic performance of RbBiNb2O7 nanosheets is characterized by measuring its dye degradation rate under a solar simulator. It is demonstrated that the RbBiNb2O7 nanosheet material effectively decolourizes Rhodamine B under visible illumination even though it has a wide bandgap (3.45 eV), and that its photocatalytic activity is greatly enhanced (similar to 4 times faster) when decorated with photodeposited Ag nanoparticles. Reducing the nanosheet size also increases the photocatalytic performance. This work demonstrates that polar 2D Dion-Jacobson phase RbBiNb2O7 is a promising candidate for photocatalytic applications. Further improvements are possible by identifying compounds with a narrower bandgap as a broad compositional window is available in this family of compounds.