Understanding the effect of polymer concentrations on the phase formation and activity of electrospun nanofibrous photocatalyst

Abstract

One-dimensional titanium dioxide electrospun nanofiber have been extensively studied, it provides channels for quick charge transfer due to their long axial ratio, but as per the experiment reports the phase formation is not conclusive about the origin of the crystallinity of titanium oxide, nor about role of polymer amount. In this study, the effect of sacrificial polymer in the electrospun solution on Ti-O bonds breaking and on the arrangement of TiO6 octahedra was obtained for different titanium oxide phase formations. In particular, polymer-metal precursor plays the role of Magnéli phase formation at low temperature. The nanofibers were prepared at different titanium butoxide and polymer concentrations with the optimization of electrospinning parameters such as electric field strength, the flow rate of the electrospinning solution, the distance between the nozzle and the receiving drum collector, and the speed of the rotating collector. The effect of polymer concentration on the crystallinity and phase compositions was examined in detail. Surprisingly, the percentage of anatase phase was found to decrease with increasing the polymer amount with a fixed annealing temperature. The experimental results show that carrier polymer polyvinylpyrrolidone is not only involved in the fiber formation through chain entanglements but plays a significant role to control TiO6 octahedral configurations and connectivity. More polymers promote edge-sharing between TiO6 rather than corner-sharing. We demonstrate the efficient photocatalytic activity of the mixed phase TiO2 nanofiber in the photocatalytic degradation of Rhodamine B dye. A significant increase in the reaction rate was observed with the increase of the Titanium butoxide:polyvinylpyrrolidone ratio. It was found that 70% anatase and 30% rutile mixed phase TiO2 nanofiber catalysts exhibit optimum photocatalytic activity with rate constant values of 0.345 min−1. The mechanism relates to the interfacial charge carrier at the junction of anatase and rutile band alignment.