Hierarchically assembled porous TiO2 nanoparticles with enhanced photocatalytic activity towards Rhodamine-B degradation

Abstract

Despite tremendous advances in the development of photocatalysts for waste water treatment, the harmful chemicals used in the synthesis reaching the water bodies add up new environmental issues. In this work, hierarchically assembled porous TiO2 nanoparticles (TiO2 NPs) were prepared by an acid-free eco-friendly hydrothermal approach via condensation of alkoxide precursor (titanium (IV) tert-butoxide). Fine tuning of textural properties was facilitated by change in the hydrothermal treatment time. The structure, morphology and the physicochemical properties of the synthesized samples were characterized by XRD, TGA, N-2 adsorption-desorption, FE-SEM, and FE-TEM analysis. N-2 adsorption-desorption displays a unique double-slit model isotherms for all the samples. The BJH mesopore distribution curves exhibit intense peak at 6.9 nm and slightly broad peak at 46.1 nm in all the samples with further broad peaks in the range of 80-95 nm. The results showed that the photocatalytic activity is highly depend on the textural properties especially pore diameter. The activity and pore diameter were found to follow the trend: TiO2-12 h > TiO2-48 h > TiO2-24 h > TiO2-6 h whereas the surface area and crystallite size follows the trend: TiO2-48 h > TiO2-12 h > TiO2-24 h > TiO2-6 h. Overall, a simple strategy is presented and could be extended to produce various metal oxides for photocatalytic degradation of various other pollutants and microorganisms.