Carbon modified TiO₂ photocatalysts for water purification

Abstract

Carbon modified TiO2 photocatalysts for water purification Carbon can form different structures with TiO2: carbon-doped TiO2, carbon coated TiO2 and composites of TiO2 and carbon. The presence of carbon layer on the surface of TiO2 as well as the presence of porous carbon in the composites with TiO2 can increase the concentration of organic pollutants on the surface of TiO2, facilitating the contact of the reactive species with the organic molecules. Carbon-doped TiO2 can extend the absorption of the light to the visible region by the narrowing of the band gap and makes the photocatalysts active under visible light irradiation. TiO2 loaded carbon can also work as a photocatalyst, on which the molecules are adsorbed in the pores of carbon and then they undergo the photocatalytic decomposition with UV irradiation. Enhanced photocatalytic activity for the destruction of some organic compounds in water was noticed on the carbon coated TiO2 and TiO2 loaded activated carbon, mostly because of the adsorptive role of carbon. However, in carbon-doped TiO2, the role of carbon is somewhat different, the replacement of carbon atom with Ti or oxygen and formation of oxygen vacancies are responsible for extending its photocatalytic activity towards the visible range.

Visible light active photocatalytic C-doped titanium dioxide films deposited via reactive pulsed DC magnetron co-sputtering: Properties and photocatalytic activity

“…However, the efficiency of p-block element doping is still under debate, as insertion of dopant impurities may accelerate the charge carrier recombination rate [12]. Nevertheless, almost all p-elements are reported to be used as TiO2 dopants to date, including nitrogen [13,14], carbon [15,16], boron [17], sulphur [18] and phosphorus [19], as well as combination of several pelements [20,21] and simultaneous doping with metallic and non-metallic elements [9,22,23].…”

Hydrothermal Synthesis of Graphene/Bi2WO6 Composite with High Adsorptivity and Photoactivity for Azo Dyes

“…Generally speaking, a new hybrid state in the band gap was formed by carbon doping, which is responsible for the narrowing of the band gap and the significant visible‐light absorption. In the case of carbon‐coated TiO 2 photocatalysts, the enhanced adsorption for dyes has been reported due to the existence of the porous carbon layer and the change of surface charges. However, the photocatalytic activity was influenced by the thickness of carbonaceous species existed at the surface of carbon‐modified TiO 2 due to the strong absorption of visible light by the carbonaceous species.…”

Uniformly dispersed CdS/CdSe quantum dots co-sensitized TiO2 nanotube arrays with high photocatalytic property under visible light

“…To extend the activity of its photocatalytic performance into the visible light region, various methods have been explored. For example, substitutional nonmetallic doping (C [4], N [5], etc.) and novel metallic (Ag [6], Pt [7], etc.)…”