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Topics in Current Chemistry (2019) 377:24
weaken the interaction of the catalyst with some aldehyde and carboxylate species. The study concludes that the sulfate surface groups have a positive catalytic
role mostly related to the modification of the pollutant adsorption (enhanced surface coverage related to the absence of crotonaldehyde) and a diminished poisoning (carbonate-related) of the surface, with relative minor effects in the coverage
and rate of the carboxylate-type reaction intermediates. This affects activity as
well as the stability of the catalyst.
4 Conclusions
The characterization of photo-catalytic materials is here analyzed through the review
of ex situ and in situ results coming from a survey analysis of the literature. Characterization aims to provide the relevant information to establish structure–activity
relationships, which can interpret the functional properties of photo-catalysts and
can allow future improvements of the field.
Up to date, the ex situ study of pre and post-reaction photo-catalysts is the most
common way of analyzing the physico-chemical properties of the solids. Multitechnique approaches leading to complete information concerning morphological,
structural, and electronic properties are required to provide insightful results. We
described the most common techniques for such purpose and provided a brief summary of the information extracted using as a representative example Ti–W binary
materials leading to doped or composite materials after calcination treatments.
However, this review article put more emphasis on presenting advanced characterization methodologies. Axiomatic to such approaches is the analysis of the interaction of the catalysts with light at the reaction cell where the physico-chemical
characterization is performed. Such analysis leads to information about the catalyst
volume (or depth from the illuminated surface), which is illuminated and which
would need to the (exclusively) probed by advanced characterization tools. For
UV and visible wavelengths, the mentioned deep is of a few micrometers (below
5) in the case of reactions using solid powders or films and of the order of 1 mm
for reactions using catalyst suspensions. Dismissing this information could drive
Fig. 12 a Correlation plot of the normalized kinetic parameter ratio (squares) and the EPR normalized
rate of hydroxyl-type radical formation (circles) vs. the reaction rate for acetaldehyde degradation using a
pure anatase (Ti) sample and a titania-ceria composite (0.025 mol% ceria; 0.025 CeTi) sample. Blue: UV
irradiation, red: visible irradiation. Reprinted with permission from Ref. [88] © 2014. b Correlation plot
of the normalized kinetic parameter ratio (squares; olive color) and the EPR normalized rate of hydroxyltype radical formation (circles; magenta color) vs. the reaction rate for toluene degradation using a pure
anatase (Ti) sample and a titania-ceria composite (xCeTi) sample. Reprinted with permission from Ref.
89 © 2014. c Correlation plot of the normalized kinetic parameter ratio (squares; olive color) and the
EPR normalized rate of hydroxyl-type radical formation (circles; magenta color) vs. the reaction rate
for toluene degradation using a pure anatase (Ti) sample, titania-ceria (CeTi), Mn: carbon nitride-titania
(g-Mn/Ti), and Mn: carbon nitride–ceria–titania (g-Mn/CeTi) composite samples. Reprinted with permission from Ref. [91] © 2014
▸
187
Reprinted from the journal
Topics in Current Chemistry (2019) 377:24
weaken the interaction of the catalyst with some aldehyde and carboxylate species. The study concludes that the sulfate surface groups have a positive catalytic
role mostly related to the modification of the pollutant adsorption (enhanced surface coverage related to the absence of crotonaldehyde) and a diminished poisoning (carbonate-related) of the surface, with relative minor effects in the coverage
and rate of the carboxylate-type reaction intermediates. This affects activity as
well as the stability of the catalyst.
4 Conclusions
The characterization of photo-catalytic materials is here analyzed through the review
of ex situ and in situ results coming from a survey analysis of the literature. Characterization aims to provide the relevant information to establish structure–activity
relationships, which can interpret the functional properties of photo-catalysts and
can allow future improvements of the field.
Up to date, the ex situ study of pre and post-reaction photo-catalysts is the most
common way of analyzing the physico-chemical properties of the solids. Multitechnique approaches leading to complete information concerning morphological,
structural, and electronic properties are required to provide insightful results. We
described the most common techniques for such purpose and provided a brief summary of the information extracted using as a representative example Ti–W binary
materials leading to doped or composite materials after calcination treatments.
However, this review article put more emphasis on presenting advanced characterization methodologies. Axiomatic to such approaches is the analysis of the interaction of the catalysts with light at the reaction cell where the physico-chemical
characterization is performed. Such analysis leads to information about the catalyst
volume (or depth from the illuminated surface), which is illuminated and which
would need to the (exclusively) probed by advanced characterization tools. For
UV and visible wavelengths, the mentioned deep is of a few micrometers (below
5) in the case of reactions using solid powders or films and of the order of 1 mm
for reactions using catalyst suspensions. Dismissing this information could drive
Fig. 12 a Correlation plot of the normalized kinetic parameter ratio (squares) and the EPR normalized
rate of hydroxyl-type radical formation (circles) vs. the reaction rate for acetaldehyde degradation using a
pure anatase (Ti) sample and a titania-ceria composite (0.025 mol% ceria; 0.025 CeTi) sample. Blue: UV
irradiation, red: visible irradiation. Reprinted with permission from Ref. [88] © 2014. b Correlation plot
of the normalized kinetic parameter ratio (squares; olive color) and the EPR normalized rate of hydroxyltype radical formation (circles; magenta color) vs. the reaction rate for toluene degradation using a pure
anatase (Ti) sample and a titania-ceria composite (xCeTi) sample. Reprinted with permission from Ref.
89 © 2014. c Correlation plot of the normalized kinetic parameter ratio (squares; olive color) and the
EPR normalized rate of hydroxyl-type radical formation (circles; magenta color) vs. the reaction rate
for toluene degradation using a pure anatase (Ti) sample, titania-ceria (CeTi), Mn: carbon nitride-titania
(g-Mn/Ti), and Mn: carbon nitride–ceria–titania (g-Mn/CeTi) composite samples. Reprinted with permission from Ref. [91] © 2014
▸
187
Reprinted from the journal