Synthesis of α-MoO3 nanobelts with preferred orientation and good photochromic performance

Stable phase α-MoO3 nanobelts with preferred orientation were successfully evolved on transforming from metastable phase h-MoO3via an aqueous approach. H+ ions play a key role in the nuclei formation and crystal growth processes. Variation of the Mo : H+ molar ratio led to MoO3 crystals with different polymorphs. Oriented α-MoO3 nanobelts along the [001] direction were achieved under a Mo : H+ ratio of 1 : 9, which is relative to a heterogeneous nucleation process on the surface of metastable phase h-MoO3. The α-MoO3 nanobelts along the [100] direction were obtained under a Mo : H+ ratio of 1 : 10; homogeneous nucleation dominated the synthesis without the presentation of h-MoO3 microrods. The α-MoO3 nanobelts with distinguishing crystalline growth orientations exhibited different photochromic behaviors.