Analysis on growth mechanism of TiO2 nanorod structures on FTO glass in hydrothermal process

Understanding the growth mechanism of TiO2 nanorods is critical for producing high-performance materials with morphology and structure control. TiO2 nanorods on FTO glass were prepared by hydrothermal method in acidic solution. The structural and morphological characteristics of thin films were investigated for different temperatures and reaction times. By the hydrolysis and protonation, monomers Ti(OH)n(OH2)6-n](4-n)+ can be formed at ambient conditions. TNRs were formed through the bonding between these monomers by olation and oxolation reactions during hydrothermal process. During the hydrothermal growth of TiO2 nanorods on FTO glass, precursors of TiO2 nanorods and nanoflowers were observed in the reactive solution and on top of TiO2 nanorod thin films. The preferential deposition of precursors and TiO2 nanostructures on top of primary TiO2 nanorods from solution resulted in significant changes in their morphology, structure, and growth orientation. A new possible growth mechanism of TiO2 nanorods is proposed based on these experimental observations.