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1590564 
Journal Article 
Fundamentals and misconceptions in photocatalysis 
Herrmann, JM 
2010 
Yes 
Journal of Photochemistry and Photobiology A: Chemistry
ISSN: 1010-6030
EISSN: 1873-2666 
216 
2-3 
85-93 
WOS:000286287300001 
Photocatalysis has presently become a major discipline
owing to two factors: (i) the intuition of the pioneers of last 20th century and (ii) the mutual
enrichment of scientists arising from different fields: photochemistry, electrochemistry,
analytical chemistry, radiochemistry, material chemistry, surface science, electronics, and
hopefully catalysis. However, heterogeneous photocatalysis belongs to catalysis, which means that
all the bases of this discipline must be respected and consequently, it has become imperative to
refocus the frame of photocatalysis to avoid misfits and misconceptions: (i) proportionality of
the reaction rate to the mass of catalyst (below the plateau due to a full absorption of
photons); (ii) implication of the Langmuir-Hinshelwood mechanism of kinetics with the initial
rate being proportional to the coverages theta in reactants; (iii) obtention of conversions
beyond the stoichiometric threshold defined as the number of potential active sites initially
present at the surface. Photonics should be respected with the photocatalytic activity being (i)
parallel to the absorbance of the photocatalyst and (ii) proportional to the radiant flux Phi,
enabling one to determine the quantum yield defined as the ratio of the reaction rate r (in
molecules converted per second) to the efficient photonic flux (in photons per second) received
by the solid. True photocatalytic normalized tests should be established to prove the real
catalytic activity of irradiated solids, independent of non-catalytic side-reactions. In
particular, dye decolorization is a misleading test, which only provides a ""visible"" and
apparent ""disappearance"" of the dye. purely photochemical but not photocatalytic.
Thermodynamics have also to be respected. The decrease of photon energy to the visible may be
thermodynamically detrimental for the generation of highly active species such as OH degrees.
Concerning solid state chemistry, it is now eventually admitted that cationic doping is
detrimental for photocatalysis. Anionic doping must be rapidly clarified or otherwise abandoned.
In conclusion, all these recommendations have to be addressed and experiments have to be operated
in suitable conditions before claiming that one deals with a true photocatalytic reaction, whose
veracity can be proved by following a protocol suggested at the end. (C) 2010 Elsevier BM. All
rights reserved. 
Photocatalysis; Fundamentals; Right protocol; Misconceptions