Synthesis of hierarchical WO₃ and Bi₂O₃/WO₃ nanocomposite for solar-driven water splitting applications

Tungsten tri oxide hierarchical nanostructures (h-WO₃) and bismuth oxide (Bi₂O₃)/h-WO₃ nanocomposite successfully prepared via a simple one-pot hydrothermal method. Structural properties of the materials reconnoitered by numerous characterization techniques such as FESEM, EDX, XRD, FT-IR and Raman. FESEM analysis designated that the h-WO₃ made of smaller layered nanorods with four axis, while the EDX analysis confirmed the elemental composition of pristine h-WO₃ and Bi₂O₃/h-WO₃ nanocomposite respectively. The XRD patterns revealed the formation of monoclinic crystal unit of WO₃ product. The as-prepared h-WO₃ nanostructures and Bi₂O₃/h-WO₃ nanocomposite displayed strong near-infrared absorption and the Raman spectrum, also indicated characteristic peaks for Bi[sbnd]O and W[sbnd]O vibrations. Based on the structural characterizations, the plausible growth mechanism for the formation of h-WO₃ nanostructures proposed. The optical properties of h-WO₃ and their nanocomposite studied through UV–Vis spectrometer and decrease in bandgap observed from 2.81 eV to 2.64 eV for the later. The photoelectrochemical (PEC) study indicated that h-WO₃ is active under visible-light region and the Bi₂O₃ incorporation further ameliorated its water splitting properties.