“…Molybdenum trioxide (MoO 3 ) is one of the most important layered materials and n-type metal oxide semiconductors, MoO 3 nanomaterials have drawn increasing attention because of their unique properties in many fields such as photochromic and electrochromic devices [1][2][3][4][5][6][7][8][9], energy storage [10][11][12][13][14], gas sensors [15,16] and catalysis [17,18]. Generally, MoO 3 is found to have mainly three crystalline polymorphs, orthorhombic MoO 3 (α-MoO 3 ), monoclinic MoO 3 (β-MoO 3 ) and hexagonal MoO3 (h-MoO 3 ), in which α-MoO 3 is the thermodynamically stable phase with layer structure and has been intensively studied.…”