One-pot hydrothermal preparation and defect-enhanced photocatalytic activity of Bi-doped CdWO 4 nanostructures.

In the field of photocatalysis, the suppression of electron-hole recombination through various defects has been an emerging trend to enhance photocatalytic activity. The separation efficiency of electron-hole recombination of well-explored wolframite structured monoclinic CdWO 4 , prepared using the one-pot hydrothermal method, was further improved by Bi 3+ doping in CdWO 4 . Studies using the partial density of states illustrated that Bi 6s and 6p orbitals altered the electronic band structure to the extent of lowering the band gap, resulting in more photon absorption. The positron annihilation lifetime studies unveiled the formation of cluster defects such as oxygen (V0o, V o 1+ , V o 2+ ) along with cadmium vacancies () in Bi-doped CdWO 4 . The coexistence and synergy of more adsorption sites of V0o, V o 1+ , V o 2+ , V Cd for dye and O 2 molecules, suitable oxide/redox band potentials, the modified electronic band structure especially owing to W-O1-Bi-O2-W linkages, together with high surface area endowed Bi-doped CdWO 4 to form ˙O 2 - radicals played a predominant role in the methyl orange degradation. All the experimental findings demonstrated conclusively that Bi 3+ doping at Cd 2+ facilitated CdWO 4 to exhibit superior photocatalytic activity.