Formation, structure and physical properties of a series of α-MoO3nanocrystals: from 3D to 1D and 2D

Abstract

A variety of α-MoO₃ nanostructures, including 1D nanobelts, 2D nanolayers and 3D nanoparticles, were prepared via three methods: sintering AMT, sintering aggregates of AMT with PEGs, and oxidating MoO₂. Our results suggested that the surface structures of the α-MoO₃ crystals obtained can be controlled by preparation conditions, including sintering temperatures, sintering times and starting materials. Several rough rules were given to explain the influence of the preparation conditions. Also, this work provided a paradigm for the structural regulation of α-MoO₃ crystals from 3D to 1D to 2D. Furthermore, the electron structures, photoluminescence performances and photocatalytic properties of the α-MoO₃ crystals were investigated. It was found that they were highly dependent on surface features of the α-MoO₃ crystals. For instance, the binding energies of Mo 3d_3/2 and Mo 3d_5/2 increased corresponding to a decrease in surface area of particles, induced by a structural transformation from 3D to 2D. Also, their photoluminescence intensity was greatly enhanced compared to that of commercial α-MoO₃. More importantly, fascinating photocatalytic properties of the as-obtained α-MoO₃ crystals were also associated with their morphologies and surface areas, for example, the smaller nanoparticles and larger surface areas of the catalysts and the higher photodegradation percentage of methylene blue. Interestingly, the photocatalytic efficiency of all the as-obtained α-MoO₃ crystals was much better than commercial α-MoO₃. A possible photocatalytic degradation mechanism was proposed. Overall, these results not only enhance our understanding of the relationship between structures and properties of inorganic nanomaterials but also could be potentially useful for new crystal design and growth of inorganic nanomaterials.