Facile synthesis and effect of thermal treatment on MoO 3−x @MoS 2 (x = 0, 1) bilayer nanostructure: toward photoelectrochemical applications

This study reports on the successful synthesis of MoO 3-x @MoS 2 (x = 0, 1) nanostructure via a one-step hydrothermal combined with the annealing method, which resulted in a well-defined nanoparticle diameter of 280–320 nm and a nanoflake thickness of 12–20 nm. X-ray diffraction analysis confirmed the presence of a hexagonal crystal phase of MoS 2 , monoclinic MoO 2 , and orthorhombic α –MoO 3 phases belonging to the P6 3 / mmc , P2 1 / c space group, and Pnma space groups, respectively. Thermal annealing resulted in a phase change from MoS 2 to MoO 3 , MoO 2 , and Mo 2 S 3 , resulting in a bilayer structure of MoO 3–x @MoS 2 and MoS 2 @Mo 2 S 3 with more catalytic activity sites. We also propose the synthesis of a shelf–hybrid MoO 3–x @MoO x S y nanosheet@nanoflake for potential use in photoelectrochemical (PEC) devices. The resulting MoO 3–x @MoS 2 -based photoanode exhibited a well-separated nanostructure that could be compatible with the MoO 3–x @MoS 2 nanosheet@nanoflake-based PEC device. The PEC measurements revealed a maximum photocurrent density ( J ) of 1.75 m A cm –2 at 0.52 V (versus RHE ), highlighting the excellent performance of our new nanostructure in the PEC application.