Sonochemical reassembling of Acacia nilotica bark extract mediated Mg doped WO3@g-C3N4 ternary nanocomposite: A robust nanophotocatalyst

•Sonochemical fabrication of novel Mg doped WO3@g-C3N4 photocatalyst.•Formation of flower like pattern was done.•Mg doped WO3@g-C3N4 shown rapid degradation of malachite green in solar radiation.••O2– radical is the main reactive species involved in the degradation.•Effect of dose and pH of the medium also investigated.