309
Characterization and Diagnosis Techniques
At different beam energies and wavelengths, specific characteristic bonds
will interact with the beam. The whole process must be performed in an
ultrahigh vacuum environment (UHV) and can reveal detailed information
about the molecular composition of a surface. The technique is often used in
industry to study catalysis, polymer surface modification, corrosion, adhesion, semiconductor and dielectric materials, electronics packaging, magnetic media, and thin film coatings [36,37].
For ES development, XPS is usually used to examine the oxidation states
of different pseudocapacitive materials. A study of this use examined the
oxidation states of ruthenium oxide powders with various water contents
[38,39]. XPS is also used to study electrode functionalization through elemental analysis. For example, it can be used to investigate and improve the
concentrations and types of nitrogen groups created by doping graphene
and CNTs by various procedures. XPS also provides chemical characterization analysis for advanced electrolytes [40,41]. All these data help researchers
determine the correlation between chemical structures and the capacitive
characteristics of materials.
7.6.6 Raman Spectroscopy (RS)
RS is a spectroscopic technique based on inelastic or Raman scattering of
a monochromatic light source on a sample. A typical Raman spectroscopy
instrument should have an excitation source (laser generation), sample
illumination and light collection optic system, spectrophotometer (for filtering and selecting wavelength), and a detector [42]. The technique measures weak inelastic scattering that occurs when photons interact with the
electron cloud (Raman effect). The molecules absorb the photons, becoming excited, and then re-emit photons of different wavelengths, returning
the molecule to a different rotational or vibrational state than its original
ground state [42,43].
A filter removes all the elastically scattered light that retains the same
wavelength as the incident photons. Energy shifting information collected
over the spectrum of wavelengths is used to study vibrational, rotational,
and other low-frequency transitions in molecules. RS gives results on most
molecular samples and is flexible for testing solids, gases, and aqueous states.
RS can also identify mixtures through characteristic peaks that fingerprint
certain functional groups in a molecule. The technique is used both qualitatively and quantitatively in these composition analyses depending on clarity
of the spectrum [43].
Raman is used as a complementary tool with TEM and XPS to examine
structures and chemical composition changes of ES electrode materials that
have undergone chemical or physical alterations, for example, characterizations of graphene, thin films, and electrode materials that will undergo
pseudocapacitive redox reactions [44–46]. It has also been used successfully to study ion insertion into carbon materials for ES electrodes such as
Characterization and Diagnosis Techniques
At different beam energies and wavelengths, specific characteristic bonds
will interact with the beam. The whole process must be performed in an
ultrahigh vacuum environment (UHV) and can reveal detailed information
about the molecular composition of a surface. The technique is often used in
industry to study catalysis, polymer surface modification, corrosion, adhesion, semiconductor and dielectric materials, electronics packaging, magnetic media, and thin film coatings [36,37].
For ES development, XPS is usually used to examine the oxidation states
of different pseudocapacitive materials. A study of this use examined the
oxidation states of ruthenium oxide powders with various water contents
[38,39]. XPS is also used to study electrode functionalization through elemental analysis. For example, it can be used to investigate and improve the
concentrations and types of nitrogen groups created by doping graphene
and CNTs by various procedures. XPS also provides chemical characterization analysis for advanced electrolytes [40,41]. All these data help researchers
determine the correlation between chemical structures and the capacitive
characteristics of materials.
7.6.6 Raman Spectroscopy (RS)
RS is a spectroscopic technique based on inelastic or Raman scattering of
a monochromatic light source on a sample. A typical Raman spectroscopy
instrument should have an excitation source (laser generation), sample
illumination and light collection optic system, spectrophotometer (for filtering and selecting wavelength), and a detector [42]. The technique measures weak inelastic scattering that occurs when photons interact with the
electron cloud (Raman effect). The molecules absorb the photons, becoming excited, and then re-emit photons of different wavelengths, returning
the molecule to a different rotational or vibrational state than its original
ground state [42,43].
A filter removes all the elastically scattered light that retains the same
wavelength as the incident photons. Energy shifting information collected
over the spectrum of wavelengths is used to study vibrational, rotational,
and other low-frequency transitions in molecules. RS gives results on most
molecular samples and is flexible for testing solids, gases, and aqueous states.
RS can also identify mixtures through characteristic peaks that fingerprint
certain functional groups in a molecule. The technique is used both qualitatively and quantitatively in these composition analyses depending on clarity
of the spectrum [43].
Raman is used as a complementary tool with TEM and XPS to examine
structures and chemical composition changes of ES electrode materials that
have undergone chemical or physical alterations, for example, characterizations of graphene, thin films, and electrode materials that will undergo
pseudocapacitive redox reactions [44–46]. It has also been used successfully to study ion insertion into carbon materials for ES electrodes such as