Bi 2 O 3 -Doped WO 3 Nanoparticles Decorated on rGO Sheets: Simple Synthesis, Characterization, Photocatalytic Performance, and Selective Cytotoxicity toward Human Cancer Cells.

Graphene derivatives and metal oxide-based nanocomposites (NCs) are being studied for their diverse applications including gas sensing, environmental remediation, and biomedicine. The aim of the present work was to evaluate the effect of rGO and Bi 2 O 3 integration on photocatalytic and anticancer efficacy. A novel Bi 2 O 3 -WO 3 /rGO NCs was successfully prepared via the precipitation method. X-ray crystallography (XRD) data confirmed the crystallographic structure and the phase composition of the prepared samples. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis confirmed the loading of Bi 2 O 3 -doped WO 3 NPs on rGO sheets. Energy-dispersive X-ray (EDX) results confirmed that all elements of carbon (C), oxygen (O), tungsten (W), and bismuth (Bi) were present in Bi 2 O 3 -WO 3 /rGO NCs. The oxidation state and presence of elemental compositions in Bi 2 O 3 -WO 3 /rGO NCs were verified by the X-ray photoelectron spectroscopy (XPS) study. Raman spectra indicate a reduction in carbon-oxygen functional groups and an increase in the graphitic carbon percentage of the Bi 2 O 3 -WO 3 /rGO NCs. The functional group present in the prepared samples was examined by Fourier transform infrared (FTIR) spectroscopy. UV analysis showed that the band gap energy of the synthesized samples was slightly decreased with Bi 2 O 3 and rGO doping. Photoluminescence (PL) spectra showed that the recombination rate of the electron-hole pair decreased with the dopants. Degradation of RhB dye under UV light was employed to evaluate photocatalytic performance. The results showed that the Bi 2 O 3 -WO 3 /rGO NCs have high photocatalytic activity with a degradation rate of up to 91%. Cytotoxicity studies showed that Bi 2 O 3 and rGO addition enhance the anticancer activity of WO 3 against human lung cancer cells (A549) and colorectal cancer cells (HCT116). Moreover, Bi 2 O 3 -WO 3 /rGO NCs showed improved biocompatibility in human umbilical vein endothelial cells (HUVECs) than pure WO 3 NPs. The results of this work showed that Bi 2 O 3 -doped WO 3 particles decorated on rGO sheets display improved photocatalytic and anticancer activity. The preliminary data warrants further research on such NCs for their applications in the environment and medicine.