Performance of mixed phase TiO2 film samples immobilized on a 2-D flat plate surface in photo catalytic applications and reusability
Abstract
TiO2 is well known photocatalyst for environmental remediation technology with a green approach of oxidation and reduction using solar irradiation. In this study three TiO2 samples were successfully synthesized using sol-gel method and then calcined at 550°C, 650°C and 750°C(termed as Ti-550, Ti-650, and Ti-750, respectively). The prepared nano-powder samples were immobilized as two dimension (2-D) thin film over glass plate surface using doctor-blade method. The characterization of the prepared photocatalysts was done using X-Ray diffractometer (XRD), UV-Vis diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) spectroscopy. The resultant samples were nanoscale systems of pure anatase, and anatase-rutile mixed phase. The band gap of the nano-catalyst samples Ti-550, Ti-650, and Ti-750 were found to be 3.04 eV, 2.97 eV, and 2.92 eV, respectively. The theoretical modeling and analysis of the samples was done by Materials Studio® software and the optical characterization was done with its CASTEP module using DFT. The performance of the samples was studied by methylene blue (MB) dye degradation kinetics under solar radiation (avg. 955 W/m2) outdoors. We conducted reusability tests on the coated samples for three cycles, with the Ti-650 sample exhibiting the highest rate constant in each degradation cycle. This may be attributed to the suitable band gap, phase ratio, and the resultant reduction in recombination of the photo-generated charge-carriers of the nano-samples. The rate constants of three continuous cycle of Ti-650 thin flim samples were calculated to be 0.00809, 0.00511 and 0.00508 per minute wherein a stabilization in performance is seen after second cycle.
Keywords
Titania, Mixed phase, Thin flim, Phase ratio, Reusability, Theoretical analysis