2 Mechanism of Oxygen Reduction Reaction
17
Fig. 2.5 Adsorption of oxygen molecules on the catalyst surface
not conducive to breaking the O–O bond. Two-electron reaction, the reduction
of oxygen on most electrode materials may be according to the mode
(iii) Birdge mode: If the nature and spatial position of the central atom are appropriate, the oxygen molecule can also be activated by two central atoms simultaneously to promote the activation of two oxygen atoms in the molecule.
This mode is obviously beneficial to the oxygen four-electronic reaction. In
principle, Griffth mode and Pauling mode belong to “single site adsorption,”
while bridge mode is “dual site adsorption.” Research results show that if there
is a small amount of underpotential deposition (UPD) on the surface of Pt,
adsorption of Ag atoms, which has a significant inhibitory effect on oxygen
reduction, indicating that oxygen molecules may be mainly adsorbed on Pt by
bridge “double position.”
For organic catalysts containing functional groups, the catalytic reduction of
oxygen is achieved by the conversion of the corresponding redoxant of the organic
catalyst, as shown in Fig. 2.6.
The following chapter will analyze the oxygen reduction mechanism by analyzing
the two main reaction pathways of oxygen reduction. At present, the main method for
studying the mechanism of oxygen reduction is to observe the intermediate product by
changing influencing factors during the reaction for inferring the reaction mechanism.
It is known from the intermediate reactants HO 2
− , H 2 O 2 , O 2
2− , HO
− , etc. that the
reaction mechanism of secondary electrons is definitely there. But at present, most
of the intermediate products are further reduced due to the means of detecting H 2 O 2 ,
resulting in whether there is a direct four-electron reaction. If the latter is practical,
the main factors affecting the ratio between the two pathways of oxygen reduction
and their mechanisms are the main problems of the study.
2.1 Mechanism of Two-Electron and Four-Electron
Reduction Reaction
Due to the complexity of the oxygen reduction reaction, the path and mechanism
of the reaction are mainly studied by experimental and theoretical calculations. The
main difference between the two-electron and the four-electron reaction pathway is
17
Fig. 2.5 Adsorption of oxygen molecules on the catalyst surface
not conducive to breaking the O–O bond. Two-electron reaction, the reduction
of oxygen on most electrode materials may be according to the mode
(iii) Birdge mode: If the nature and spatial position of the central atom are appropriate, the oxygen molecule can also be activated by two central atoms simultaneously to promote the activation of two oxygen atoms in the molecule.
This mode is obviously beneficial to the oxygen four-electronic reaction. In
principle, Griffth mode and Pauling mode belong to “single site adsorption,”
while bridge mode is “dual site adsorption.” Research results show that if there
is a small amount of underpotential deposition (UPD) on the surface of Pt,
adsorption of Ag atoms, which has a significant inhibitory effect on oxygen
reduction, indicating that oxygen molecules may be mainly adsorbed on Pt by
bridge “double position.”
For organic catalysts containing functional groups, the catalytic reduction of
oxygen is achieved by the conversion of the corresponding redoxant of the organic
catalyst, as shown in Fig. 2.6.
The following chapter will analyze the oxygen reduction mechanism by analyzing
the two main reaction pathways of oxygen reduction. At present, the main method for
studying the mechanism of oxygen reduction is to observe the intermediate product by
changing influencing factors during the reaction for inferring the reaction mechanism.
It is known from the intermediate reactants HO 2
− , H 2 O 2 , O 2
2− , HO
− , etc. that the
reaction mechanism of secondary electrons is definitely there. But at present, most
of the intermediate products are further reduced due to the means of detecting H 2 O 2 ,
resulting in whether there is a direct four-electron reaction. If the latter is practical,
the main factors affecting the ratio between the two pathways of oxygen reduction
and their mechanisms are the main problems of the study.
2.1 Mechanism of Two-Electron and Four-Electron
Reduction Reaction
Due to the complexity of the oxygen reduction reaction, the path and mechanism
of the reaction are mainly studied by experimental and theoretical calculations. The
main difference between the two-electron and the four-electron reaction pathway is