Temperature-Dependent Morphology Modulation of MoO2 from 1D Nanoribbons to 2D Nanoflakes for Enhanced Two-Dimensional Electrode Applications

The morphology modulation of target crystals is important for understanding their growth mechanisms and potential applications. Herein, we report a convenient method for modulating the morphology of MoO₂ by controlling different growth temperatures. With an increase in growth temperature, the morphology of MoO₂ changes from a nanoribbon to a nanoflake. Various characterization methods, including optical microscopy, atomic force microscopy, (vertical and tilted) scanning electron microscopy, Raman spectroscopy, high-resolution transmission electron microscopy, and selected area electron diffraction, were performed to unveil the morphology modulation and lattice structure of MoO₂. Both MoO₂ nanoribbons and nanoflakes display a standing-up growth mode on c-sapphire substrates, and their basal planes are MoO₂(100). Further investigations into devices based on MoS₂ with Au/Ti/MoO₂ electrodes show the potential applications of MoO₂ in two-dimensional electrodes. These findings are helpful for the synthesis of MoO₂ with different morphologies and applications in the field of optoelectronic nanodevices.