High photoconductive combustion synthesized TiO2 derived nanobelts for photocatalytic water purification under solar irradiation

Abstract

Drinking water scarcity is a major issue that needs to be addressed seriously. Water needs to be purified from organic pollutants and bacterial contamination. In this study, sunlight driven photocatalysis for the degradation of dyes and bacterial inactivation has been conducted over TiO₂ nanoparticles (CST) and TiO₂ nanobelts (CSTNB). TiO₂ nanoparticles were synthesized by a solution combustion process using ascorbic acid as a fuel. Acid etched TiO₂ nanobelts (CSTNB) were synthesized using combustion synthesized TiO₂ as a novel precursor. The mechanism of formation of TiO₂ nanobelts was hypothesized. The antibacterial activity of combustion synthesized TiO₂ and acid etched TiO₂ nanobelts were evaluated against Escherichia coli and compared against commercial TiO₂. Various characterization studies like X-ray diffraction analysis, BET surface area analysis, diffused reflectance measurements were performed. Microscopic structures and high resolution images were analyzed using scanning electron microscopy, transmission electron microscopy. The extent of photo-stability and reusability of the catalyst was evaluated by conducting repeated cycles of photo degradation experiments and was compared to the commercial grade TiO₂. The reactive radical species responsible for high photocatalytic and antibacterial activity has been determined by performing multiple scavenger reactions. The excellent charge transfer mechanism, high generation of hydroxyl and hole radicals resulted in enhanced photocatalytic activity of the acid etched TiO₂ nanobelts compared to commercial TiO₂ and nanobelts made from commercial TiO₂.