Structure evolution from Prussian-blue nanocubes to hollow nanocage composites via sodium tungstate etching.

The formation path of hollow complex nanocages prepared via Na2WO4·2H2O etching, using Prussian blue as a template, is tracked, which confirms the existence of a central cross structure inside the etching products. A mechanism based on etching along edges is described. The gas sensor designed with an Fe-W hollow complex exhibits excellent performance toward CH3S3CH3.