Defects Induced Magnetism in WO3 and Reduced Graphene Oxide-WO3 Nanocomposites

A series of reduced graphene oxide (rGO)-WO3 nanocomposites were prepared by hydrothermal method using GO and tungsten complex. The nanocomposites were characterized by powder XRD, Raman spectroscopy, FT-IR spectroscopy, HRTEM, XPS, photoluminescence (PL), and magnetic studies. The structural analysis confirms the hexagonal crystal structure and formation of rGO-WO3 nanocomposites. HRTEM images show rod-like shape WO3 distributed on the wrinkle structure of rGO sheets. XPS results confirm the oxidation state and oxygen vacancies present in the samples. PL spectra of the samples show blue emission and indicate the existence of surface defects and oxygen vacancies. The M-H loop of rGO-WO3 nanocomposites reveal that the co-existence of both ferro and antiferromagnetism at room temperature. The incorporation of rGO sheets notably increase magnetic behavior of composites due to extended C-C bond conducts much stronger coupling between the 5d and 6s orbitals of tungsten and carbon atoms.