“…Among the developed 2D materials, molybdenum trioxide is one of the most promising to be implemented in electronic devices, such as resistive memory devices, 1 eld effect biosensors, 2 electronic ink based printable transistors, 3 batteries 4 or supercapacitors. 5,6 Molybdenum trioxide can exhibit several phases, being the orthorhombic a-MoO 3 the thermodynamically stable phase, 7 whereas monoclinic b-MoO 3 and hexagonal h-MoO 3 phases have been reported as metastable phases of the MoO 3 . 8 The a-MoO 3 phase exhibits weak van der Waals forces between the stacked planes of MoO 6 octahedra, along the [010] direction in the crystal structure, which allows the fabrication of 2D layers with a few nanometers thickness.…”