Synthesis of layered perovskite Ag,F-Bi ₂ MoO ₆ /rGO: A surface plasmon resonance and oxygen vacancy promoted nanocomposite as a visible-light photocatalyst

Heterojunction z-scheme based Ag,F co-doped Bi ₂ MoO ₆ /reduced graphene oxide (Ag,F@BMO/rGO) photocatalysts were synthesized via a facile solvothermal method. The present work describes the improved photocatalytic activity of BMO/rGO nanocomposite by co-doping of F ⁻ and Ag ⁺ ions, to remove RhB from aqueous solution. The XRD, N ₂ adsorption, SEM, TEM, EDS, UV–Vis DRS, FT-IR, Raman, and PL measurements were employed to characterize the crystallographic, morphological, and optical properties. X-ray diffraction analysis suggests that crystal growth of all the as-prepared nanoparticles with different F ⁻ and Ag ⁺ contents has occurred in Aurivillius phase and the crystal structure did not affected by doping. The insertion of Ag ⁺ and F ⁻ into Bi ₂ MoO ₆ led to a red-shift in the absorption edge of nanocomposite and decrease the band gap energy from 2.78 eV to 2.6 eV, due to the synergetic effects of Surface Plasmon Resonance and surface oxygen vacancy induced by Ag ⁺ and F ⁻ , respectively. These beneficial properties are explored toward the photodegradation of RhB under visible-light source, resulting in better yields at lesser exposure time. The photocatalytic activity was significantly influenced by rGO in the nanocomposite, which was 2 times higher than that of pure Bi ₂ MoO ₆ , by effective separation of the charge carriers. The separation behaviors of photogenerated electron-hole were also systematically investigated by the PL. Based on the radical trapping experiments, photogenerated holes and O ₂ ^•− were the main active species in RhB photodegradation and the detailed decolorization pathway has been suggested, using liquid chromatography/mass spectrometry (LC/MS) technique. In addition, the Ag,F@BMO/rGO nanocomposite does not display dramatic reduction of catalytic performance after four recycles, reveals its great prospect and promising application for water purification.