Aqueous synthesis of molybdenum trioxide (h-MoO3, α-MoO3·H2O and h-/α-MoO3 composites) and their photochromic properties study

Molybdenum trioxide (h-MoO3, α-MoO3·H2O and h-/α-MoO3 composites) were prepared by a simple method in aqueous solution at 90–95 °C, without using autoclave or other complex equipment. The synthetic conditions for different phases of MoO3 were studied. The ratio of MoO42−:H+ and reaction temperature play important roles for the crystal phases of MoO3. By changing the amount of H+ ions, the samples can be controlled as h-MoO3 microrods or α-MoO3·H2O microbelts. h-/α-MoO3 composites in homogeneous structure were obtained at higher temperatures. The study on the transformation process of h-MoO3 → α-MoO3·H2O → α-MoO3 would be helpful in designing functional MoO3 materials. The h-MoO3 microrods and h-/α-MoO3 composites showed good photochromic behavior under sunlight irradiation.