Impact of morphology and nitrogen and carbon codoping on photocatalytic activity of TiO₂ as environmental catalysts

We present three different morphologies of TiO₂ structures-namely, nanoparticles, nanowires, and dandelion-like particles-by wet chemistry routes as environmental catalysts for the degradation of Methylene Blue. The band-gap energy of these morphologies is tuned by codoping with carbon and nitrogen atoms and controlling the synthesis processing parameters. The physical and chemical properties of the synthesized samples are characterized by X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy. The nanoparticles (15-40 nm) and nanowires (diameter of ∼100 nm) mainly have an anatase structure, whereas the dandelion-like particles (diameter of 15-20 μm) show a rutile phase. The reduction percentage in band-gap energy of TiO₂ is dependent on its morphology, ranking in the following order: nanoparticles > nanowires > dandelion-like particles, with the latter exhibiting the lowest value of 3.05 eV. The impact of TiO₂ morphology, crystal structure, band-gap energy, and carbon and nitrogen codoping is studied on the degradation of Methylene Blue under ultraviolet A (UVA) irradiation.