Application of X-Ray Photoelectron Spectroscopy in Materials …
419
Table 2 Elemental composition of prepared photocatalysts calculated by XPS analysis with std.
deviation
Sample ID
Elements (%)
Ti
Al
O
C
0%AT
25.3 ± 0.07
–
52.0 ± 0.33
22.4 ± 0.19
0.5%AT
19.3 ± 1.21
1.2 ± 0.14
38.8 ± 4.01
39.6 ± 3.22
1%AT
20.8 ± 0.32
1.6 ± 0.17
44.4 ± 3.08
32.5 ± 2.16
1.5%AT
22.2 ± 0.10
1.9 ± 0.04
48.8 ± 1.21
27.8 ± 1.60
3%AT
21.9 ± 0.51
2.3 ± 0.07
49.3 ± 0.86
26.1 ± 0.91
Reprinted (adapted) with permission from reference 3. Copyright (2019) American Chemical
Society
Table 3 atomic ratio of Ce 3+
ions. Reprinted (adapted)
with permission reference 4
Copyright (2016) The Royal
Society of Chemistry
Sample ID
Atomic ratio
Pure TiO 2
–
Pure CeO 2
13.5
Ce 0.1 TiO x
30.4
Ce 0.2 TiO x
22.0
Ce 0.3 TiO x
31.0
Ce 0.4 TiO x
21.0
Ce 0.5 TiO x
21.3
Mathur et al. doped Fe into α-MnO 2 and from XPS analysis, it was determined
that Fe is present in Fe
0 (metallic) and Fe
+2 oxidation states in 47.18 atomic %
and 52.82 atomic % respectively in 0.022FeMn material [5]. The authors did
sequential doping of Fe in α- MnO 2 and observed that with increase in Fe doping,
the surface concentration of Fe first increases, then decreases. In addition, the
diffusion-limiting current density of the samples for electrochemical oxygen
reduction reaction (ORR) as well as electrochemical oxygen reduction reaction
(OER) followed the same trend as that of Fe surface concentration. It was also
observed that Fe concentration is proportional to improving the onset potential
and current density of MnO 2 .
(c) To find out the presence of pollutant at catalysts surface and its interaction with catalyst: Fig. 4a presents the survey spectrum of the bare catalyst,
norfloxacin (fluoroquinolone) adsorbed catalyst and regenerated catalyst. A new
peak appeared near 687 eV in the norfloxacin adsorbed catalyst is corresponding
to the F 1s present in this fluoroquinolone molecule, that confirms its presence
over the catalyst’s surface. However, surface regains its properties when regenerated as no such peak was observed in regenerated catalyst. The detailed XPS
analysis revealed that atomic percentage ratio of Ti:O was changed from 1:2.1
to 1:4.2 in bare catalyst and pollutant adsorbed catalyst due to the presence of
extra O from norfloxacin. Ravinder et al. [3] also utilized this surface sensitive
419
Table 2 Elemental composition of prepared photocatalysts calculated by XPS analysis with std.
deviation
Sample ID
Elements (%)
Ti
Al
O
C
0%AT
25.3 ± 0.07
–
52.0 ± 0.33
22.4 ± 0.19
0.5%AT
19.3 ± 1.21
1.2 ± 0.14
38.8 ± 4.01
39.6 ± 3.22
1%AT
20.8 ± 0.32
1.6 ± 0.17
44.4 ± 3.08
32.5 ± 2.16
1.5%AT
22.2 ± 0.10
1.9 ± 0.04
48.8 ± 1.21
27.8 ± 1.60
3%AT
21.9 ± 0.51
2.3 ± 0.07
49.3 ± 0.86
26.1 ± 0.91
Reprinted (adapted) with permission from reference 3. Copyright (2019) American Chemical
Society
Table 3 atomic ratio of Ce 3+
ions. Reprinted (adapted)
with permission reference 4
Copyright (2016) The Royal
Society of Chemistry
Sample ID
Atomic ratio
Pure TiO 2
–
Pure CeO 2
13.5
Ce 0.1 TiO x
30.4
Ce 0.2 TiO x
22.0
Ce 0.3 TiO x
31.0
Ce 0.4 TiO x
21.0
Ce 0.5 TiO x
21.3
Mathur et al. doped Fe into α-MnO 2 and from XPS analysis, it was determined
that Fe is present in Fe
0 (metallic) and Fe
+2 oxidation states in 47.18 atomic %
and 52.82 atomic % respectively in 0.022FeMn material [5]. The authors did
sequential doping of Fe in α- MnO 2 and observed that with increase in Fe doping,
the surface concentration of Fe first increases, then decreases. In addition, the
diffusion-limiting current density of the samples for electrochemical oxygen
reduction reaction (ORR) as well as electrochemical oxygen reduction reaction
(OER) followed the same trend as that of Fe surface concentration. It was also
observed that Fe concentration is proportional to improving the onset potential
and current density of MnO 2 .
(c) To find out the presence of pollutant at catalysts surface and its interaction with catalyst: Fig. 4a presents the survey spectrum of the bare catalyst,
norfloxacin (fluoroquinolone) adsorbed catalyst and regenerated catalyst. A new
peak appeared near 687 eV in the norfloxacin adsorbed catalyst is corresponding
to the F 1s present in this fluoroquinolone molecule, that confirms its presence
over the catalyst’s surface. However, surface regains its properties when regenerated as no such peak was observed in regenerated catalyst. The detailed XPS
analysis revealed that atomic percentage ratio of Ti:O was changed from 1:2.1
to 1:4.2 in bare catalyst and pollutant adsorbed catalyst due to the presence of
extra O from norfloxacin. Ravinder et al. [3] also utilized this surface sensitive