Titanium dioxide (TiO₂) is widely used in hydrogen production, water and air purification, and solar cells. Pure TiO₂ cannot utilize the energy from visible light region ( 3.0 eV) as its relatively large bandgap (3.0 eV and 3.2 eV). Energy in visible light region (45%) of solar energy is wasted and only 5% in UV region is utilized by pure TiO₂. Bandgap modification of TiO₂ can change the band structure and achieve visible light active photocatalysis. Transition metals doped TiO₂ had been synthesized to obtain visible light active photocatalyst. However, transition metals doped TiO₂ are usually synthesized by toxic or expensive precursors. Non-metal doped TiO₂ shows good photoactivity by using relative non-toxic precursors.

A green, non-toxic and low-cost carbon source was used...[ Read more ]

Titanium dioxide (TiO₂) is widely used in hydrogen production, water and air purification, and solar cells. Pure TiO₂ cannot utilize the energy from visible light region (< 3.0 eV) as its relatively large bandgap (3.0 eV and 3.2 eV). Energy in visible light region (45%) of solar energy is wasted and only 5% in UV region is utilized by pure TiO₂. Bandgap modification of TiO₂ can change the band structure and achieve visible light active photocatalysis. Transition metals doped TiO₂ had been synthesized to obtain visible light active photocatalyst. However, transition metals doped TiO₂ are usually synthesized by toxic or expensive precursors. Non-metal doped TiO₂ shows good photoactivity by using relative non-toxic precursors.

A green, non-toxic and low-cost carbon source was used to prepare visible-light photocatalysts with enhanced photoactivity for oxidation of organic micropollutants in water. Carbon precursors including sucrose, glucose, and fructose, were investigated. Electron and chemical properties of the photocatalysts were investigated by X-ray diffraction (XRD), N₂ physisorption, UV/Vis diffusive reflectance spectroscopy (UV/Vis DRS) and X-ray Photoemisson spectroscopy.

Carbon doped TiO₂ showed bandgap modification, increase in specific surface area, and surface group modification. Bandgap modification of TiO₂ absorbs of energy in visible light region which activate photocatalysis under visible light irradiation. It is the only necessary process for pure TiO₂ achieving photocatalysis under visible light irradiation. Larger specific area provides more active sites for the photocatalytic reaction. Surface group modification benefits electron transfer thus reduction in electron-hole recombination during photocatalysis.

Low power light source 6 W fluorescent lamps were used instead of laboratory light source (e.g., 500 W high pressure mercury lamp or 250 W metal halide lamp) to demonstrate the practicability and high activity of the photocatalyst. Photocatalytic remediation of 2,4-dichlorophenol (2,4-DCP) and methylene blue in water were carried out in a laboratory reactor irradiated with the lamps equipped with UV filter. The results showed that the new catalyst even at low irradiation performed 28 times better than commercial P25 TiO₂ photocatalyst.