Two-Dimensional Titanium Dioxide–Surfactant Photoactive Supramolecular Networks: Synthesis, Properties, and Applications for the Conversion of Light Energy

Abstract

The desire to harness solar energy to address current global environmental problems led us to investigate two-dimensional (2D) core–shell hybrid photocatalysts in the form of a 2D-TiO2–surfactant, mainly composed of fatty acids. The bulk products, prepared by two slightly different methods, consist of stacked host–guest hybrid sheets held together by van der Waals forces between alkyl carboxylate moieties, favoring the synergistic conjugation of the photophysical properties of the core and the hydrophobicity of the self-assembled surfactant monolayer of the shell. X-ray diffraction and the vibrational characteristics of the products revealed the influence of synthesis strategies on two types of supramolecular aggregates that differ in the core chemical structure, guest conformers of alkyl surfactant tails and type, and the bilayer and monolayer of the structure of nanocomposites. The singular ability of the TiO2 core to anchor carboxylate leads to commensurate hybrids, in contrast to both layered clay and layered double-hydroxide-based ion exchangers which have been previously reported, making them potentially interesting for modeling the role of fatty acids and lipids in bio-systems. The optical properties and photocatalytic activity of the products, mainly in composites with smaller bandgap semiconductors, are qualitatively similar to those of nanostructured TiO2 but improve their photoresponse due to bandgap shifts and the extreme aspect-ratio characteristics of two-dimensional TiO2 confinement. These results could be seen as a proof-of-concept of the potential of these materials to create custom-designed 2D-TiO2–surfactant supramolecular photocatalysts.

Impact of Copper(II)-Imidazole Complex Modification on Polycrystalline TiO2: Insights into Formation, Characterization, and Photocatalytic Performance

“…This complex is characterized by a broad IR band spanning 3434-3465 cm −1 , narrow bands at 1638 and 1402 cm −1 , and a faint absorption band at 442 cm −1 . The broad band at 3434-3465 cm −1 corresponds to the stretching mode ν(O-H) of hydroxyl (OH) groups, while the bands at 1638 and 1432 cm −1 represent the bending mode δ(O-H) of OH groups [52,53]. The absorption at 442 cm −1 is attributed to the stretching mode ν(Ti-O) of the Ti-O bond, typically found in a higher-energy region around 534 cm −1 [54,55].…”

Crystal Design and Photoactivity of TiO2 Nanorod Template Decorated with Nanostructured Bi2S3 Visible Light Sensitizer

“…The rod morphology helps to improve the electron injection and collection efficiency of TiO 2 semiconductor [ 1 , 2 , 3 , 4 , 5 ]. However, the wide band gap nature of TiO 2 engenders poor response to visible light [ 6 , 7 ]. In order to improve the photoactivity of TiO 2 , the strategy of semiconductor coupling is often used to enhance the solar energy conversion and utilization of TiO 2 [ 8 ].…”