Chapter 8
Modifications of Photocatalysts by Doping
Methods
8.1 Preparation of Visible Light-Responsive TiO 2
Photocatalysts by Chemical Doping Modification
Methods
In order to improve the visible light activity of TiO 2 , many modification methods
have been developed in recent years, like doping impurities, coupling semiconductors, dye sensitization, and so on. After the modification, the visible light-driven
TiO 2 can use the solar energy in dealing with the environmental pollution and new
energy development. For instance, the dye-sensitized TiO 2 has been widely used in
preparing solar cells, owing to its strong visible light absorption ability. In 1991,
Michael Grätzel and Brian O’Regan described a photovoltaic cell, created from lowto medium-purity materials through low-cost processes, which exhibited a commercially realistic energy-conversion efficiency [1]. The device is based on a 10-μmthick, optically transparent film made with TiO 2 particles having a few nanometers
in size, coated with a monolayer of dye to sensitize the film for light harvesting. The
overall light-to-electric energy conversion is 7.1–7.9% for simulated solar light and
12% for diffuse daylight. The large current densities and high stability of the solar
cells based on dye-sensitized colloidal TiO 2 films are making practical applications
feasible. Since then, the record of energy conversion for the dye-sensitized TiO 2 -
based solar cells is constantly improved year by year [2–8]. In 1998, the solar cell
based on dye-sensitized mesoporous TiO 2 films converts photons to electric current
with a high yield of 33%, which is also achieved by Prof. Michael Grätzel [9]. At
present, the photoelectric conversion efficiency of TiO 2 -based solar cells has stabilized to be more than 10%, but its cost of manufacturing is still high.
Some other modified visible light-responsible TiO 2 especially the dopingmodified TiO 2 also attracted much attention and have been applied to organic
pollutant photodegradation and water splitting reaction. Hence, in this section, we
would like to introduce the modification methods related to dope trace impurity into
TiO 2 , including chemical synthesis like high-temperature sintering in an atmosphere,
© Springer Nature Singapore Pte Ltd. 2018
J. Zhang et al., Photocatalysis, Lecture Notes in Chemistry 100,
https://doi.org/10.1007/978-981-13-2113-9_8
197
Modifications of Photocatalysts by Doping
Methods
8.1 Preparation of Visible Light-Responsive TiO 2
Photocatalysts by Chemical Doping Modification
Methods
In order to improve the visible light activity of TiO 2 , many modification methods
have been developed in recent years, like doping impurities, coupling semiconductors, dye sensitization, and so on. After the modification, the visible light-driven
TiO 2 can use the solar energy in dealing with the environmental pollution and new
energy development. For instance, the dye-sensitized TiO 2 has been widely used in
preparing solar cells, owing to its strong visible light absorption ability. In 1991,
Michael Grätzel and Brian O’Regan described a photovoltaic cell, created from lowto medium-purity materials through low-cost processes, which exhibited a commercially realistic energy-conversion efficiency [1]. The device is based on a 10-μmthick, optically transparent film made with TiO 2 particles having a few nanometers
in size, coated with a monolayer of dye to sensitize the film for light harvesting. The
overall light-to-electric energy conversion is 7.1–7.9% for simulated solar light and
12% for diffuse daylight. The large current densities and high stability of the solar
cells based on dye-sensitized colloidal TiO 2 films are making practical applications
feasible. Since then, the record of energy conversion for the dye-sensitized TiO 2 -
based solar cells is constantly improved year by year [2–8]. In 1998, the solar cell
based on dye-sensitized mesoporous TiO 2 films converts photons to electric current
with a high yield of 33%, which is also achieved by Prof. Michael Grätzel [9]. At
present, the photoelectric conversion efficiency of TiO 2 -based solar cells has stabilized to be more than 10%, but its cost of manufacturing is still high.
Some other modified visible light-responsible TiO 2 especially the dopingmodified TiO 2 also attracted much attention and have been applied to organic
pollutant photodegradation and water splitting reaction. Hence, in this section, we
would like to introduce the modification methods related to dope trace impurity into
TiO 2 , including chemical synthesis like high-temperature sintering in an atmosphere,
© Springer Nature Singapore Pte Ltd. 2018
J. Zhang et al., Photocatalysis, Lecture Notes in Chemistry 100,
https://doi.org/10.1007/978-981-13-2113-9_8
197