Investigation of doping effects of Ni to enhance photocatalytic activity of WO 3 for advanced degradation of tetracycline in aqueous environment

Ni was successfully doped into WO 3 lattice to enhance its photocatalytic activity. The Ni dopants acted as nuclei during crystallization leading to Ni-WO 3 crystal size increase. However, the doped Ni substituted several W 6+ of the WO 3 leading to lattice distortion preventing agglomeration of these formed crystals resulting in Ni-WO 3 particle size decrease. Therefore, Ni-WO 3 crystals were larger than WO 3 crystals while Ni-WO 3 particles were much smaller than WO 3 particles. Finally, Ni dopants created a transitional level between conduction and valence bands of the WO 3 to narrow its band gap and to increase charge separation to improve photocatalytic Tetracycline degradation efficiency. Graphical abstract