Indium Hydroxides, Oxyhydroxides, and Oxides Nanocrystals Series

Indium hydroxides, oxyhydroxides, and oxides are important n-type semiconductors and have wide applications in material fields. In this Article, a series of In(OH)3 and InOOH nanocrystals with different structures and morphologies, such as nanocubes, nanorods, multipods, and nanoparticles, have been synthesized selectively through a liquid-phase reaction, by adjusting the alkalinity and polarity of the solvent. It is found that InOOH multipods are in the orthorhombic phase and their arms grow along nonequivalent faces. Cubic and hexagonal In2O3 can be obtained from In(OH)3 and InOOH, respectively, while size and morphology can be maintained to a certain extent. Gas sensors were fabricated by using In2O3, and a device based on the multipods shows the best responses to ethanol vapor. XRD, TEM, HRTEM, SEM, and SAED have been used to characterize these nanocrystals. This work provides a preliminary investigation into the structural-based gas-sensing properties of these nanocrystals.