Chapter 4
Preparation of Reduced TiO 2–x
for Photocatalysis
4.1 Introduction
Titanium dioxide (TiO 2 ) photocatalyst has received plenty of attention since it was
applied for the photocatalytic hydrogen generation from water splitting [1]. Owing
to its abundance, non-toxicity, and chemical stability, TiO 2 is widely used in areas
such as pigments, cosmetics, paper, plastics, catalysis, solar cells, and antibacterial
agents. As a catalyst, TiO 2 shows applications in photodegradation of organic
pollutants, hydrogen evolution from water, CO 2 photoreduction, lithium-ion batteries (LIBs), and dye-sensitized solar cells (DSSCs).
However, the practical applications of TiO 2 are limited to UV region of solar light
because of its wide bandgap (3.2 eV for anatase phase). It means that only a small
part (~5%) of the solar energy can be well utilized by TiO 2 photocatalysts. In order
to solve these problems, a lot of modification methods were employed to improve the
solar light response of this catalyst and modify its bandgap engineering. Conventional approaches have been introduced for TiO 2 modification, such as nonmetal
doping, noble metal grafting, dye-sensitization, special facet exposure, compositing
with other materials, etc. However, new approaches are still required in performance
improvement, to match the rising demands for energy consuming and environmental
protection.
The concept of reduced TiO 2 , or TiO 2–x , photocatalyst was early introduced
decades ago [2–5], and it was usually used to describe TiO 2 catalysts with Ti
3+
ions induced by doping, undercoordinated Ti atoms caused by oxygen vacancies, or
hydrogen implantation [6]. Besides, plenty of works have been reported on reduced
facets of TiO 2 materials [7], especially with the help of density functional theory
(DFT) [8] and scanning tunneling microscope (STM) studies [3, 9, 10]. Recently, the
investigation of TiO 2–x phtotocatalysts develops rapidly, owing to its superior
photocatalytic and photoelectrochemical (PEC) performance. A lot of new preparations methods were employed for the synthesis of TiO 2–x , and the surface properties
© 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_4
75
Preparation of Reduced TiO 2–x
for Photocatalysis
4.1 Introduction
Titanium dioxide (TiO 2 ) photocatalyst has received plenty of attention since it was
applied for the photocatalytic hydrogen generation from water splitting [1]. Owing
to its abundance, non-toxicity, and chemical stability, TiO 2 is widely used in areas
such as pigments, cosmetics, paper, plastics, catalysis, solar cells, and antibacterial
agents. As a catalyst, TiO 2 shows applications in photodegradation of organic
pollutants, hydrogen evolution from water, CO 2 photoreduction, lithium-ion batteries (LIBs), and dye-sensitized solar cells (DSSCs).
However, the practical applications of TiO 2 are limited to UV region of solar light
because of its wide bandgap (3.2 eV for anatase phase). It means that only a small
part (~5%) of the solar energy can be well utilized by TiO 2 photocatalysts. In order
to solve these problems, a lot of modification methods were employed to improve the
solar light response of this catalyst and modify its bandgap engineering. Conventional approaches have been introduced for TiO 2 modification, such as nonmetal
doping, noble metal grafting, dye-sensitization, special facet exposure, compositing
with other materials, etc. However, new approaches are still required in performance
improvement, to match the rising demands for energy consuming and environmental
protection.
The concept of reduced TiO 2 , or TiO 2–x , photocatalyst was early introduced
decades ago [2–5], and it was usually used to describe TiO 2 catalysts with Ti
3+
ions induced by doping, undercoordinated Ti atoms caused by oxygen vacancies, or
hydrogen implantation [6]. Besides, plenty of works have been reported on reduced
facets of TiO 2 materials [7], especially with the help of density functional theory
(DFT) [8] and scanning tunneling microscope (STM) studies [3, 9, 10]. Recently, the
investigation of TiO 2–x phtotocatalysts develops rapidly, owing to its superior
photocatalytic and photoelectrochemical (PEC) performance. A lot of new preparations methods were employed for the synthesis of TiO 2–x , and the surface properties
© 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_4
75