Facile synthesis and efficient photoelectrochemical reaction of WO3/WS2 core@shell nanorods utilizing WO3∙0.33H2O phase

•Facile and effective synthesis of 1D WO3/2D WS2 core-shell nanorods.•Introducing a novel route to synthesize 2D WS2 shell layer on WO3 nanorods utilizing WO3∙0.33H2O phase.•Significantly enhanced photoelectrochemical performance of WO3/WS2 core-shell nanorods.•Applicable to various types of heterojunction WO3/2D WS2 for photoelectrochemical applications. [Display omitted] One-dimensional (1D) WO3/two-dimensional (2D) WS2 heterojunction nanostructures are of great interest in various photoelectrochemical (PEC) and electrochemical applications. In this study, we introduced a simple and effective route to synthesize 2D WS2 shell layer on WO3 nanorods by utilizing WO3∙0.33H2O phase. The formation of WO3∙0.33H2O nanorods was critically affected by hydrothermal reaction temperature. The WO3∙0.33H2O phase was preferentially transformed into hexagonal WO3 and 2D WS2 through oxidation and sulfurization at 450 °C, respectively. The 2D WS2 shell layer was more favorably formed on WO3 nanorods, which were synthesized at 180 °C and possessed a significant amount of WO3∙0.33H2O phase (referred to as W-180), than on WO3 nanorods with predominant monoclinic WO3 phase, which were synthesized at 200 °C (referred to as W-200). Thus, the WO3/WS2 core@shell nanorods from W-180 exhibited significantly enhanced PEC performance because of the improved charge transfer properties attributed to the advantageous heterojunction effect of 1D WO3/2D WS2. The new synthesis route from WO3∙0.33H2O phase to 2D WS2 can be applied to synthesize various WO3/2D WS2 heterojunction nanostructures, such as thin films, nanoparticles, and nanorods.