Controllable synthesis of WO 3 /Co 1-δ WO 4 composite nanopowders for photocatalytic degradation of methylene blue (MB)

Systematical design and controllable synthesis of nanometer heterogeneous structure have attracted much attention in the photocatalytic field. The tungsten oxide/cobalt tungstate (WO 3 /Co 1-δ WO 4 ) nanoparticles with heterogeneous interface were synthesized by co-precipitation process. The XRD pattern shows shifts of diffraction peaks of CoWO 4 to lower angle side, implying the deficient of Co 2+ in the lattice. The internal field across the heterogeneous structure transfers the photon-generated electrons from the conduction band of WO 3 to that of Co 1-δ WO 4 . The enhancement of the electron density greatly improves the photoluminescence emission intensity at a magnitude of around 2 × 10 6 in comparison with that of pure WO 3 or CoWO 4 . The photocatalytic efficiency was inspected by exposing the methylene blue (MB) mixing with 1% WO 3 /Co 1-δ WO 4 nanopowders to the visible light for degradation. The main optical absorption band of MB at 664 nm decays from 2.35 to 0.04 cm −1 after photo-degradation for 3.5 h, suggesting excellent photocatalytic performance. Graphical abstract