Chapter 2
In Situ Characterization of Photocatalytic
Activity
The photocatalytic reactions are initiated from the photoinduced electrons and holes
on the surfaces of photocatalyst, which further react with water/oxygen to form
reactive oxygen species (ROS) with high reactivity including superoxide anion
radical (
•
O 2
À ), hydrogen peroxide (H 2 O 2 ), singlet oxygen (
1 O 2 ), and hydroxyl
radical (
•
OH). The determination of ROS formed from the semiconductor-based
photocatalysis and the in situ tracking of the formation sites; trajectory and kinetics
are essential for understanding the photocatalytic redox mechanism, thus helping to
guide the structure design of the photocatalyst. This chapter focuses on the application of fluorescence, infrared, Raman, electron spin resonance (ESR), and surface
photovoltage spectroscopies and atomic force microscopy (AFM) to reveal the
above process on the surface of the photocatalyst regarding the surface heterogeneity, crystal facet, and molecule conformation. These studies have greatly promoted
the design and application of photocatalyst.
2.1 Fluorescence
Fluorescence is one of the most important ways for the identification, quantification,
and kinetics evaluation of ROS. Fluorophores including luminol, fluorescein, coumarin, and tetrafluoroborate are commonly used probes for ROS [1]. The dehydrogenation, esterification, and the intramolecular electron transferring may cause the
on–off, off–on, or wavelength shift of the fluorescence. Such variation provides
specific information about the ROS formation on the surface of photocatalysts.
© 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_2
17
In Situ Characterization of Photocatalytic
Activity
The photocatalytic reactions are initiated from the photoinduced electrons and holes
on the surfaces of photocatalyst, which further react with water/oxygen to form
reactive oxygen species (ROS) with high reactivity including superoxide anion
radical (
•
O 2
À ), hydrogen peroxide (H 2 O 2 ), singlet oxygen (
1 O 2 ), and hydroxyl
radical (
•
OH). The determination of ROS formed from the semiconductor-based
photocatalysis and the in situ tracking of the formation sites; trajectory and kinetics
are essential for understanding the photocatalytic redox mechanism, thus helping to
guide the structure design of the photocatalyst. This chapter focuses on the application of fluorescence, infrared, Raman, electron spin resonance (ESR), and surface
photovoltage spectroscopies and atomic force microscopy (AFM) to reveal the
above process on the surface of the photocatalyst regarding the surface heterogeneity, crystal facet, and molecule conformation. These studies have greatly promoted
the design and application of photocatalyst.
2.1 Fluorescence
Fluorescence is one of the most important ways for the identification, quantification,
and kinetics evaluation of ROS. Fluorophores including luminol, fluorescein, coumarin, and tetrafluoroborate are commonly used probes for ROS [1]. The dehydrogenation, esterification, and the intramolecular electron transferring may cause the
on–off, off–on, or wavelength shift of the fluorescence. Such variation provides
specific information about the ROS formation on the surface of photocatalysts.
© 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_2
17