The Design of TiO₂ Nanostructures (Nanoparticle, Nanotube, and Nanosheet) and Their Photocatalytic Activity

Abstract

Density functional theory (DFT) calculation is carried out to access the band structure and density of states (DOS) based on the models of TiO2 nanoparticle, nanotube, and nanosheet, predicting the order of the photocatalytic activity for three different nanostructures. Sol–gel method and hydrothermal method are used to achieve desired morphologies: nanoparticles, nanotubes, and nanosheets (fragmentized nanotubes). The photocatalytic activity ranks in the order of nanosheets > nanotubes > nanoparticles, which is consistent with theoretical prediction. It was revealed that the enlargement of band gap is caused by the quantum confinement effect; the prolonged lifetime of photogenerated electrons and increased specific surface areas are dependent on the morphology of the nanostructure. All these factors contribute to the improvement of the photocatalytic activity for nanostructures. Our results can guide the design and selection of low-dimensional nanomaterials with desired morphology and improved photoelectric functional properties, which can be used in many fields, such as solar cells, photocatalysis, and photosynthesis.

Preparation of 2D hydroxyl-rich carbon nitride nanosheets for photocatalytic reduction of CO2

“…The efficient separation of charge carriers has been studied by measuring the PL spectra, uorescence lifetime and photocurrent. [50][51][52] The radiative process (s 2 ) is directly related to the recombination of photogenerated electrons and holes. 10a shows the PL spectra collected with an excitation wavelength of 350 nm.…”

Effect of Ionic Compounds of Different Valences on the Stability of Titanium Oxide Colloids

“…Since the discovery of the photoelectric effect in titania [12], enormous effort has been made to develop photocatalytic systems composed of titanium oxide nanostructures or their composites [13][14][15][16][17]. It was also discovered that the shape [18] of the titania particles and the ionic environment [19] influences the photocatalytic activity. Moreover, novel titanium oxide-based substances were applied in solar cells [20], electrode materials [21], supercapacitors [22], inks [23] and electronics [24].…”

2D Hybrid Nanostructure of Reduced Graphene Oxide–CdS Nanosheet for Enhanced Photocatalysis

“…[6][7][8][9][10][11] On the other hand, one-dimensional (1D) and two-dimensional (2D) (nanorods, nanowires, nanotubes and nanosheet) semiconducting nanostructures are thought to play a crucial role in next-generation building blocks for solar energy harvesting and photocatalysis, due to their fascinating physicochemical properties and their unique geometric and electronic properties. [12][13][14][15][16][17][18][19][20] Emphasis has been given on wide band gap semiconductor nanomaterials, like TiO 2 and ZnO based nanostructures, [21][22] which exhibit ultraviolet region absorption instead of visible light harvesting. However, II-IV semiconductor, like CdS has a suitable band gap (2.4 eV) which is appropriate for sunlight absorption.…”