TiO2 nanotube arrays with visible light catalytic

Area of Science:

• Materials Science
• Nanotechnology
• Photocatalysis

Background:

• Titanium dioxide (TiO2) is a widely studied semiconductor photocatalyst.
• Controlling the crystal structure of TiO2 is crucial for optimizing its photocatalytic efficiency.
• Visible light photocatalysis is desirable for sustainable environmental applications.

Purpose of the Study:

• To synthesize TiO2 nanotube arrays with varying crystal structures via calcination.
• To evaluate the photocatalytic performance of these TiO2 nanotubes for rhodamine B degradation under visible light.
• To elucidate the structure-property relationships governing the enhanced photocatalytic activity.

Main Methods:

• Anodization was used to prepare TiO2 nanotube arrays.
• Calcination at different temperatures was employed to modify crystal structures.
• Characterization involved X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis diffuse reflectance spectroscopy (DRS), Raman, photoluminescence (PL), and electrochemical testing.
• Photocatalytic activity was assessed by degrading rhodamine B under visible light.

Main Results:

• TiO2 nanotubes calcined at 600°C exhibited the highest photocatalytic activity.
• This optimal sample possessed a mixed anatase-rutile crystalline phase.
• The anatase-rutile phase reduced charge transfer resistance and suppressed electron-hole recombination.
• Visible light absorption and photoelectric properties were favorably altered, enhancing performance.

Conclusions:

• Calcination temperature significantly influences the crystal phase and photocatalytic performance of TiO2 nanotubes.
• The mixed anatase-rutile phase in TiO2 nanotubes calcined at 600°C is key to their superior visible-light photocatalytic activity.
• Hole (h+) and hydroxyl radical (•OH) were identified as the primary active species in the degradation process.