Visible-light assisted CdO nanowires photocatalyst for toxic dye degradation studies

Abstract In the present work, CdO nanowires (NWs) as a visible-light assisted photocatalyst was developed and studied for photocatalytic degradation of representative hazardous colour dyes, which are often exposed to water sources by the textile industries. The uniform CdO NWs were synthesized using the simple soft chemical route. Further, the CdO NWs were annealed in air from 350 to 450 °C with an interval of 50 °C and were characterized to understand their physical and optical properties. Structural analysis showed that the crystallinity increases with annealing temperature till 400 °C. FESEM study of CdO thin films revealed the transformation of NWs into earthworm-like chain NWs after thermal annealing. The optical absorption study revealed the presence of direct band-to-band transition with band-gap ranging from 2.17 to 1.55 eV for as-deposited to annealed films, respectively. The photocatalytic activity of the CdO NWs annealed at 400 °C was tested by visible-light-induced degradation of Indigo carmine (IC), Ponceau-S (PS), and Congo red (CR) dyes. In the presence of CdO NWs photocatalyst, the efficiency was found to be 30% for IC, 39% for PS and 57% for CR dyes. The CdO NWs photocatalyst showed enhanced photodegradation i.e., ∼ 1.9 times and ∼1.4 times higher for CR in comparison to IC and PS, respectively.