Molybdenum Oxide Nanoparticle Aggregates Grown by Chemical Vapor Transport

In this study, the advanced chemical vapor transport (CVT) method in combination with the quenching effect is introduced for creating molybdenum oxide nanoparticle arrays, composed of the hierarchical structure of fine nanoparticles (NPs), which are vertically grown with a homogeneous coverage on the individual carbon fibers of carbon fiber paper (CFP) substrates. The obtained molybdenum oxide NPs hold a metastable high-temperature γ-Mo₄O₁₁ phase along with a stable α-MoO₃ phase by the quenching effect. Furthermore, such a quenching effect forms thinner and smaller nanoparticle aggregates by suppressing the growth and coalescence of primary particles. The molybdenum oxide nanoparticle aggregates are prepared using two different types of precursors: MoO₃ and a 1:1 (mol/mol) mixture of MoO₃ and activated carbon. The results characterized using X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy show that the relative amount of α-MoO₃ to γ-Mo₄O₁₁ within the prepared NPs is dependent on the precursor type; a lower amount of α-MoO₃ to γ-Mo₄O₁₁ is obtained in the NPs prepared using the mixed precursor of MoO₃ and carbon. This processing-structure landscape study can serve as the groundwork for the development of high-performance nanomaterials in various electronic and catalytic applications.