Formation of nanomaterial internal cavity based on process similar to bread-baking

Abstract Since 1990s, the design and control of morphology for nanomaterials has been attracting great attention. Nanomaterials with internal cavity structure are promising for their great properties related to catalysis, purification, drug delivery, electronic materials, energy storage and so on. Herein a method to fabricate WO3 nanosheets with internal cavity was reported. Being quite different from those methods reported before, e.g. using template or Kirkendall effect, this process verified a novel hollow structure forming method similar to bread-baking, including generation of dense shell on the interface and internal steam expansion. SEM observation was used by changing accelerating voltage in situ to confirm the smooth surface and porous interior of WO3 nanosheets. Besides, the BET, TEM and SAXS measurements revealed the hollow structure of as-fabricated samples.