Multi-amine-assisted crystal growth of large-sized α-MoO₃ elongated nano-plates

Large-sized α-MoO₃ elongated nano-plates were synthesized by the introduction of multi-amines such as ethylene di-amine and diethylene tri-amine (DETA) in the conventional hydrothermal reaction. DETA made large hexagonal rods with an h-MoO₃ intermediate phase containing H₂O, NH₄OH, and DETA ions. During the hydrothermal reaction, the hexagonal rods were transformed to elongated α-MoO₃ nano-plates by the re-dissolution of h-MoO₃ and re-growth to α-MoO₃ because DETA retarded the preferred growth reaction of the MoO₆ octahedra to the [001] direction and helped the MoO₆ octahedra to grow in the [100] direction. In addition, DETA promoted α-MoO₃ nano-belts to be assembled into elongated nano-plates by oriented attachment because the multi-ammonium groups in the DETA backbone could adhere to the α-MoO₃ nano-belts due to attractive Coulomb interactions.