Modulation in the Band Dispersion of Bi2WO6 Nanocrsytals Using the Electronegativity of Transition Elements for Enhanced Visible Light Photocatalysis

A reduced band gap of similar to 2 eV and an optimal band edge offset for water splitting with enhanced charge kinetics in the case of Bi2WO6 remains a fixture in photocatalysis. Bulk Bi2WO6 has a band gap of 2.8 eV; reducing the band gap by lattice modification increases recombination, while the size effect of nanoparticles increases the band gap. Herein, the synergistic effect of a reduced size effect and crystal structure modification is studied for novel BTWO [T = Cr, Mn, Fe, Co, and Ni] nanostructures. X-ray diffraction (XRD) results confirm the formation of an isostructural orthorhombic pyrochlore phase in BTWO [Mn, Fe, and Ni] and a cubic phase in BiCrWO6. Raman and XPS results are consistent with XRD depicting the chemical states of the prepared samples. As a representative, BiCrWO6 has shown the highest photocatalytic efficiency for the degradation of rhodamine B. The UV-visible analysis depicts a reduced band gap, UPS analysis reveals reduced work function and ionization energy. The charge carriers separation and migration are demonstrated using photoluminescence and electrochemical impedance studies. The ability to generate the radicals during the chemical reaction is analyzed using electron paramagnetic resonance studies. A relation between electronegativity of the elements and their impact on the band dispersion in Bi2WO6 nanostructures for visible light photocatalytic activity is detailed.