Delamination and Dissolution of Titanate Nanowires: A Combined Structure and in Situ Second Harmonic Generation Study

• Published in: Journal of physical chemistry. C 2011-06, Vol.115 (25), p.12381-12387
• Main Authors: Schürer, Benedikt, Elser, Michael J, Sternig, Andreas, Peukert, Wolfgang, Diwald, Oliver
• Format: Article
• Language: English
• Subjects: C: Nanops and Nanostructures
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp203709a

Mechanistic insights into shape and structure transformation of metal oxide nanostructures are critical to our understanding of how synthesis parameters and chemical environment affect their properties. Na2Ti3O7 nanowires, which are composed of titanate nanosheets and which contain sodium ions in the interlayer region, are thermodynamically unstable in acid solutions. At room temperature nanosheet delamination along the nanowire length axis leads to coiled-up nanoscrolls. At 373 K, a dissolution and TiO2 recrystallization process gives rise to colloidal anatase nanoparticles. The impact of temperature on different reaction pathways is attributed to differences in the energy barriers associated with the two transformation channels. We comprehensively investigated these reactions with X-ray diffraction and electron microscopy and for the first time tracked processes at the solid–liquid interface such as nanosheet delamination by time-resolved second harmonic generation (SHG) measurements. The applicability of the SHG method for in situ studies which address the transformation of layered nanostructures in aqueous solution even at high electrolyte concentrations is demonstrated.