Prussian blue analogue nanocubes with hollow interior and porous walls encapsulated within reduced graphene oxide nanosheets and their sodium-ion storage performances

Metal-organic frameworks (MOFs) have attracted considerable research attention due to their functional characteristics such as tailorable architecture and adjustable pore sizes. In particular, the assembly of such MOFs has been widely studied because of their unprecedented physicochemical properties. In this paper, a strategy is presented for the synthesis of nanostructure-tunable MOFs assembled within reduced graphene oxide (rGO) nanosheets via colloidal spray pyrolysis process. The spray pyrolysis of Prussian blue nanocubes and graphene oxide (GO) nanosheets dispersed in an aqueous solution, and the subsequent sulfidation heat-treatment yields Prussian blue analogue nanocubes with a hollow interior and porous walls encapsulated within rGO. Through spray pyrolysis process, large-scale synthesis of nanostructure-tunable MOFs assembled within rGO nanosheets could be realized in one-pot process. The MOFs can be uniformly encapsulated within rGO nanosheets through spray pyrolysis process, which is beneficial for improving cycle and rate performances, when applied as the anode material for sodium ion batteries. In particular, the rGO matrix acts as a highway for electron transport, resulting in remarkable discharge capacities of 413 mA h g−1, even at a high current density of 10 A g−1. To provide supplementary structural integrity for a longer cycle life, polydopamine-derived N-doped carbon is coated on the spherical composite, and the electrochemical performance of the anode material for sodium ion storage is analyzed in detail. It is believed that this strategy could pave the way towards the synthesis of superstructures filled with structure-tunable MOFs that have wide applicability.