α-MoO₃ Crystals with a Multilayer Stack Structure Obtained by Annealing from a Lamellar MoS₂/g-C₃N₄ Nanohybrid.

Transition metal oxides and chalcogenides have recently attracted great attention as the next generation of 2-D materials due to their unique electronic and optical properties. In this study, a new procedure for the obtaining of highly crystalline α-MoO₃ is proposed as an alternative to vapor-phase synthesis. In this approach, a first reaction between molybdate, citrate and thiourea allowed to obtain MoS₂, which-upon calcination at a temperature of 650 °C in the presence of g-C₃N₄-resulted in MoO₃ with a definite plate-like shape. The colorless (or greenish) α-MoO₃ nanoplates obtained with this procedure featured a multilayer stack structure, with a side-length of 1⁻2 μm and a thickness of several nanometers viewed along the [010] direction. The nucleation-growth of the crystal can be explained by a two-dimensional layer-by-layer mechanism favored by g-C₃N₄ lamellar template.