Fabrication of WO3 nanostructures by anodization method for visible-light driven water splitting and photodegradation of methyl orange

Visible light-responsive WO3 nanostructures were synthesized by anodization in a NH4F/Na2SO4 electrolyte solution. Applied potential and anodization time play an important role in the formation of self-organized WO3 nanostructures, further developed upon anodization. The average pore diameter of ∼80 nm with thickness of∼300 nm of WO3 nanoporous layer was successfully synthesized at 50 V for 15 min. The uniform and regular WO3 nanoporous layer exhibited better photocurrent density of∼0.18 mA/cm2 at 0.7 V vs. SCE and better photodegradation of MO solution of ∼50% after 5 h of visible-light illumination. The larger active surface area of WO3 nanoporous layer played a significant role to generate more electron-hole pairs, which triggered the PEC water splitting reaction and photodegradation reaction much more effectively.