Impact of Synthesis pH on Nano-structural, Opto-electronic, and Photocatalytic Properties of TiO2 Nanoparticles

TiO2 is a wide bandgap semiconductor nanomaterial that has attracted considerable attention for its diverse applications. The structure, crystal size, morphology, and bandgap of TiO2 play a vital role in photocatalysis and are related to the synthesis conditions and methods. In this study, the nanoparticles were synthesized using the sol-gel method and investigated the effect of varying pH on their structural and opto-electronic properties. The X-ray diffraction patterns revealed anatase phase in all the samples and presence of rutile phase (4wt%) at pH 7. The smallest crystal size was observed at pH 8, while a neutral pH gave larger crystal sizes. The TiO2 grains were observed to have a nearly spherical spongy-like shape and agglomerated nanoparticles. The bandgap energy was found to increase with the increase pH value until neutral. The photocatalytic activity of the NPs was investigated by the degradation of methylene blue solution. The TiO2 nanoparticles obtained at a pH of 8 exhibited the highest degradation efficiency of 82 % at a degradation rate of 0.0048/min.