Multiwalled carbon nanotubes decorated with nitrogen, palladium co-doped TiO₂ (MWCNT/N, Pd co-doped TiO₂) for visible light photocatalytic degradation of Eosin Yellow in water

Multiwalled carbon nanotube (MWCNT/N), Pd co-doped TiO₂ nanocomposites were prepared by calcining the hydrolysis products of the reaction of titanium isopropoxide, Ti(OC₃H₇)₄ containing multiwalled carbon nanotubes with aqueous ammonia. The prepared samples were characterised by Fourier transform infrared spectroscopy, Raman spectroscopy, thermogravimetric analysis, diffuse reflectance UV–Vis spectrophotometry (DRUV–Vis), XRD, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). DRUV–Vis analysis confirmed the red shift in the absorption edge at lower MWCNT percentages. SEM and TEM images showed the complete coverage of the MWCNTs with clusters of anatase TiO₂ at low MWCNT percentages. Higher MWCNT levels led to their aggregation and consequently poor coverage by N, Pd co-doped TiO₂. The photocatalytic activities of the nanocomposites were monitored by photodegradation of Eosin Yellow under simulated solar and visible light irradiation (λ > 450 nm). Irradiation with simulated solar radiation gave higher dye-degradation rates compared to visible radiation. The optimum MWCNT weight percentage in the composites was found to be 0.5. High degradation-rate constants of 3.42 × 10⁻² and 5.18 × 10⁻³ min⁻¹ were realised for the 0.5% MWCNT/N, Pd co-doped TiO₂ composite, using simulated solar light and visible light, respectively.