Abstract
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Herein, we report a novel method for the formation of hollow Prussian blue analogue (CoFe���PBA) nanocubes, using spherical silica particles as sacrificial templates. In the first step, silica cores are coated by a CoFe���PBA shell and then removed by etching with hydrofluoric acid (HF). The cubic shape of CoFe���PBA is well-retained even after the removal of the silica cores, resulting in the formation of hollow CoFe���PBA cubes. The specific capacity of the hollow CoFe���PBA nanocubes electrodes is about two times higher than that of solid CoFe���PBA nanocubes as storage materials for sodium ions. Such an improvement in the electrochemical properties can be attributed to their hollow internal nanostructure. The hollow architecture can offer a larger interfacial area between the electrolyte and the electrode, leading to an improvement in the electrochemical activity. This strategy can be applied to develop PBAs with hollow interiors for a wide range of applications.