Hierarchical TiO₂ Nanoflakes and Nanoparticles Hybrid Structure for Improved Photocatalytic Activity

Abstract

Three-dimensional TiO 2 microspheres with different hierarchical nanostructures were synthesized by the synergistic strategies of ultrafast electrochemical spark discharge spallation process followed by thermal treatment. The morphology, crystal structure, surface area, and photocatalytic activity of the hierarchical nanostructures were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, surface area analysis, and UV−vis spectroscopy respectively. The nanostructure of hierarchical microspheres undergoes three evolution steps, which includes the change from nanosheets into hybrid nanoflakes/ nanoparticles and finally to nanoparticles as calcination temperature increases, in line with the predicable trend of increase in crystallinity and decrease in specific surface area. Compared to other forms of calcined TiO 2 samples (nanosheets and nanoparticles), the hybrid TiO 2 nanoflake/ nanoparticle hierarchical porous structure exhibits a higher photocatalytic activity for the degradation of organic compounds (methyl orange and bisphenol A). This is attributed to their larger specific surface area (∼116 m 2 /g), more abundant porosity, and good crystallinity. On the basis of this hybrid structure, a visible light sensitive Ag/TiO 2 microsphere photocatalyst is designed which shows faster degradation rate under the visible light illumination (>420 nm). The porous microspheric photocatalyst does not lose its activities after recycled use, showing great potential for practical application in environmental cleanup.

Oil-in-water self-assembled Ag@AgCl QDs sensitized Bi2WO6: Enhanced photocatalytic degradation under visible light irradiation

“…Meanwhile, a broad prominent absorption in the visible light region of 450-600 nm was observed in Ag@AgCl-based composites, which could be attributed to the surface plasmon resonance (SPR) effect of Ag [26][27][28]. The surface plasmon absorption on the surface of Ag derives from a collective oscillation of free electrons excited by the matching photon energy.…”

Advanced approach for degradation of recalcitrant by nanophotocatalysis using nanocomposites and their future perspectives

“…Nanoflakes are a special class of nanomaterials that are characterized to possess high photocatalytic activity under visible light irradiation when compared to their pure form nanoparticles due to the changes in optoelectronic properties (Tang et al 2012;Zhang et al 2011) These nanoflakes can be prepared by alkaline or at low-temperature hydrothermal techniques. Ong et al (2013) reported the photocatalytic degradation of methyl orange by metalloaded ZnO nanoflakes.…”

“…Ong et al (2013) reported the photocatalytic degradation of methyl orange by metalloaded ZnO nanoflakes. Tang et al (2012) reported the improved photocatalytic degradation of methyl orange and bisphenol by hierarchical TiO 2 nanoflakes.…”

Nano Ag@AgBr surface-sensitized Bi2WO6 photocatalyst: oil-in-water synthesis and enhanced photocatalytic degradation

“…The prominent absorption band in the visible-light region could be attributed to the surface plasmon resonance (SPR) effect of Ag. Meanwhile, a broad prominent absorption in the visible-light region of 450-800 nm was observed in Ag@AgBr-based composites, which could be attributed to the surface plasmon resonance (SPR) effect of Ag [24][25][26]. The surface plasmon absorption on the surface of Ag derives from a collective oscillation of free electrons excited by the matching photon energy.…”