Morphology-controlled synthesis of hematite nanocrystals and their facet effects on gas-sensing properties.

An oriented attachment growth process was found for the morphology and shape control of various inorganic materials in solution-based systems. In this Article, a well-defined iron oxide polyhedron was prepared via a simple hydrothermal method. Detailed investigations revealed that the single-crystalline polyhedron evolved from polycrystalline aggregates. The shape and size control of the iron oxide crystals were achieved by simply adjusting the synthesis parameters. The as-prepared products exhibit excellent gas sensing selectivity to ethanol vapor. The gas-sensing ability is closely related to the exposure of high-index facets.