Chapter 9
Hollow or Yolk–Shell-Type Photocatalyst
The photocatalytic efficiency of bulk semiconductor particles generally suffers from
poor diffusion efficiency of photo-generated carriers from the inside to the surface
and low absorption efficiency to the incident light. The introduction of cavity inside
the semiconductor particle has been proven effective to form accessible active sites
throughout the bulk particle and enhance the light absorption efficiency through
multiple scattering effects. Moreover, through reasonably spatial arrangement of
different components in a single particle, the hole–electron separation degree can be
enhanced, and functions such as plasmon resonance absorption and magnetic separation can be extra assembled. In this chapter, we mainly discuss the synthesis and
characteristics-tuning of hollow-, yolk–shell-, hierarchical-, and tubular-type
photocatalyst and the structural effect on the photocatalytic performance.
9.1 Synthesis
The generation of void inside the semiconductor can be achieved mainly through
non-template (Kirkendall, Ostwald ripening) and hard-template (silica, carbon,
polymer colloids) routes [1–3]. Both methods can form cavitory semiconductors
with versatile structures and highly tunable dimensions concerning core, shell,
and void.
9.1.1 Non-template Route
Ostwald ripening is the most commonly used strategy for non-template synthesis of
cavitory semiconductor [2, 4, 5]. A typical example is the formation of hollow
anatase TiO 2 nanospheres using TiF 4 as the precursor in aqueous system and
under hydrothermal conditions (Fig. 9.1) [2]. Inner nanospace and highly organized
© 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_9
223
Hollow or Yolk–Shell-Type Photocatalyst
The photocatalytic efficiency of bulk semiconductor particles generally suffers from
poor diffusion efficiency of photo-generated carriers from the inside to the surface
and low absorption efficiency to the incident light. The introduction of cavity inside
the semiconductor particle has been proven effective to form accessible active sites
throughout the bulk particle and enhance the light absorption efficiency through
multiple scattering effects. Moreover, through reasonably spatial arrangement of
different components in a single particle, the hole–electron separation degree can be
enhanced, and functions such as plasmon resonance absorption and magnetic separation can be extra assembled. In this chapter, we mainly discuss the synthesis and
characteristics-tuning of hollow-, yolk–shell-, hierarchical-, and tubular-type
photocatalyst and the structural effect on the photocatalytic performance.
9.1 Synthesis
The generation of void inside the semiconductor can be achieved mainly through
non-template (Kirkendall, Ostwald ripening) and hard-template (silica, carbon,
polymer colloids) routes [1–3]. Both methods can form cavitory semiconductors
with versatile structures and highly tunable dimensions concerning core, shell,
and void.
9.1.1 Non-template Route
Ostwald ripening is the most commonly used strategy for non-template synthesis of
cavitory semiconductor [2, 4, 5]. A typical example is the formation of hollow
anatase TiO 2 nanospheres using TiF 4 as the precursor in aqueous system and
under hydrothermal conditions (Fig. 9.1) [2]. Inner nanospace and highly organized
© 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_9
223