Interfacial self-assembly engineering for constructing a 2D flexible superlattice polyoxometalate/rGO heterojunction for high-performance photovoltaic devices†
2D materials have strong intermolecular van der Waals forces, and 2D superlattice heterostructures have exhibited many dramatic photo-electrochemical properties for energy conversion and storage. Herein, based on the excellent properties of reduced graphene and superlattice structures, we constructed a 2D flexible superlattice polyoxometalate/rGO heterojunction with enhanced electron–hole separation via interfacial self-assembly engineering to further fabricate DSSCs based on the heterojunction-modified photoanode, which exhibited good electron transport properties. Selecting two kinds of Dawson POMs (P2W15V3, P2W18 and the corresponding heteropoly blue) as the research object, the polyoxometalate superlattice structure was obtained by the self-assembly strategy, and characterized by IR, UV-Vis, XRD, EDX and XPS. The TEM and AFM results indicated that the monolayer POM superlattice structure and superlattice polyoxometalate/rGO heterojunction were successfully obtained. The superlattice P2W18(HPB)/rGO heterojunction was introduced into the DSSCs photoanode, and electrochemical tests indicated that the superlattice polyoxometalate/rGO heterojunction improved the electron–hole separation rate, inhibited the electron recombination, and improved the photoelectric conversion efficiency to 8.09%. The 2D superlattice heterojunction remarkably improved the electrochemical performances of the energy storage and conversion systems.