Heterostructured Visible‐Light‐Active Photocatalyst of Chromia‐Nanoparticle‐Layered Titanate

Abstract

An efficient visible‐light active photocatalyst of porous CrOx–Ti1.83O4 nanohybrid with a 1:1 type ordered heterostructure is synthesized through a hybridization between a chromia cluster and exfoliated titanate nanosheets. The present nanohybrids are found to have a large surface area (ca. 250–310 m2 g–1) and an intense absorption of visible light, ascribable, respectively, to the formation of a porous structure and the hybridization of titanate with narrow‐bandgap chromium oxide. After the calcination at 400 °C, the nanohybrid shows an enhanced photocatalytic activity to effectively decompose organic compounds under the irradiation of visible light (λ > 420 nm). The present study highlights the exfoliation–restacking route as a very powerful way to develop efficient visible‐light‐harvesting photocatalysts with excellent thermal stability.

Porous Titania Nanosheet/Nanoparticle Hybrids as Photoanodes for Dye-Sensitized Solar Cells

“…An electrostatic interaction between negatively charged titanate nanosheets and positively charged TiO2 nanoparticles is believed to be a driving force for the formation of such type disordered heterostructure. 22 The discernible broad 001 reflection for the NH film after heat treatment shifted toward the higher angle side (2θ = 2.46 º), indicative of the shrinkage in basal spacing mainly attributed to the dehydroxylation of TiO2 nanosol particles but maintenance of the NH structure. The formation of the layered NH structure was further confirmed using TEM analysis.…”

“…Table 1 22,23,30,31,53,54 within the layered NH film, which results in an increase in electron density in TiO2, and thus the shift of Fermi level. 55 As evidenced above, the large surface area makes it accessible for more dye-adsorption, and the light scattering effect of the re-assembled exfoliated titanates favour enhanced light-harvesting efficiency by increasing the optical length serving as light-scattering shield, and thereby enhanced Jsc for the cell with the layered NH film.…”

“…22,23,31 Titanate nanosheets (Ti0.91O2) derived from delamination of layered compounds have unique structural characteristic of ultimate two-dimensional anisotropy with extremely small thickness in the subnano-to nanometer scales, which leads to new physical and chemical properties for nanosheets. 32 In addition, the exfoliation of layered metal oxides into 2D nanosheets 33,34 (Ti0.91O2 nanosheets) makes it possible to pillar large-sized (TiO2) nanoparticles into the interlayer space of host materials through an exfoliation-restacking process of nanosheets and guest particles.…”

“…Layered nanohybrids (NHs) by pillaring semiconducting nanoparticles such as CdS, α-Fe2O3, and TiO2 [21][22][23][24] into layered inorganic compounds [25][26][27][28][29][30] have recently drawn growing attention in photocatalysis, due to their large surface area as well as suppressed electronhole recombination because of electron transfer between guest and host. 22,23,31 Titanate nanosheets (Ti0.91O2) derived from delamination of layered compounds have unique structural characteristic of ultimate two-dimensional anisotropy with extremely small thickness in the subnano-to nanometer scales, which leads to new physical and chemical properties for nanosheets.…”

“…23,35,36 The obtained pillared NHs possesses highly controllable physical and chemical properties. 22,[37][38][39] In particular, due to the enlarged interlayer distance, the total surface area is significantly increased, facilitating chemical adsorption or reaction. Moreover, the energy band difference between guest and host will enhance the charge transfer between them.…”