Controllable Synthesis and Gas-Sensing Properties of Zinc Oxide Nanocrystals With Exposed Different Percentage of Facets

A facile and controllable one-step hydrothermal method to synthesize nanodisks and nanorods of zinc oxide with exposed different crystal facets of (0001), (11̅00), (011̅0), and (101̅0) has been realized. It was found that the average percentage of exposed (0001) crystal facets follows the order of nanodisks > nanorods-1 > nanorods-2 > nanorods-3, while the average percentage of exposed (11̅00), (011̅0), and (101̅0) crystal facets decreases monotonically. The sensing tests to NO
₂
indicate that the nanodisks exhibit higher sensitivity. It has also been validated that the (0001) crystal facet has the highest surface energy and the lowest binding energy, which is considered to be the key factor of high gas-sensing by the calculations of density functional theory. This finding will open a new window to explore the relationship between gas-sensing and exposed facets and will be useful for designing gas-sensing materials with specifically exposed surfaces.