Chapter 2
Mechanism of Oxygen Reduction
Reaction
Zuzhen Zhao and Pei Kang Shen
Abstract This chapter describes the mechanism and kinetics of oxygen reduction.
Therefore, the adsorption of O 2 on transition metals will be discussed in detail below.
The adsorption of oxygen molecules on the surface of the catalyst is complicated.
It not only has the associative adsorption and dissociative adsorption adsorbed in
molecular form but also the oxygen atoms can enter the interior of the metal lattice
to form surface oxides. The adsorption of oxygen on a metal catalyst can be regarded
as adsorption on metal ions, similar to the case where metal and oxygen are bonded in
a transition metal complex. 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 fourelectron reaction pathway is the intermediate product. So from the middle product
ratio of the reaction and the influencing factors, we know that they are methods of
continuous two-electron reactions. Although there have been many studies on the
mechanism of oxygen reduction, and many convincing theories have been proposed,
there are still many details on the main reaction pathways for oxygen reduction which
are not clear enough.
Keywords Oxygen reduction reaction · ORR · H 2 O 2 · Multielectron
Oxygen reduction reaction is the basic reaction in electrochemical reaction. It is the
cathode reaction of a series of electrochemical cells such as fuel cell, secondary
lithium-air cell, metal-air cell, etc. It is also the main conjugate reaction occurring
during the process of metal corrosion. The kinetics of the oxygen reduction reaction
is slower than that of the anode reaction, and at the same time, the potential on
the electrode such as Pt is higher, which makes the active metal or carrier on the
Z. Zhao
Research Institute of Tsinghua University in Shenzhen, Shenzhen, Guangdong, China
P. K. Shen (B)
Collaborative Innovation Center of Sustainable Energy Materials, Guangxi Key Laboratory of
Electrochemical Energy Materials, College of Chemistry and Chemical Engineering, Guangxi
University, Nanning, Guangxi 530004, China
e-mail: pkshen@gxu.edu.cn
© Guangxi Science & Technology Publishing House 2021
P. K. Shen, Electrochemical Oxygen Reduction,
https://doi.org/10.1007/978-981-33-6077-8_2
11
Mechanism of Oxygen Reduction
Reaction
Zuzhen Zhao and Pei Kang Shen
Abstract This chapter describes the mechanism and kinetics of oxygen reduction.
Therefore, the adsorption of O 2 on transition metals will be discussed in detail below.
The adsorption of oxygen molecules on the surface of the catalyst is complicated.
It not only has the associative adsorption and dissociative adsorption adsorbed in
molecular form but also the oxygen atoms can enter the interior of the metal lattice
to form surface oxides. The adsorption of oxygen on a metal catalyst can be regarded
as adsorption on metal ions, similar to the case where metal and oxygen are bonded in
a transition metal complex. 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 fourelectron reaction pathway is the intermediate product. So from the middle product
ratio of the reaction and the influencing factors, we know that they are methods of
continuous two-electron reactions. Although there have been many studies on the
mechanism of oxygen reduction, and many convincing theories have been proposed,
there are still many details on the main reaction pathways for oxygen reduction which
are not clear enough.
Keywords Oxygen reduction reaction · ORR · H 2 O 2 · Multielectron
Oxygen reduction reaction is the basic reaction in electrochemical reaction. It is the
cathode reaction of a series of electrochemical cells such as fuel cell, secondary
lithium-air cell, metal-air cell, etc. It is also the main conjugate reaction occurring
during the process of metal corrosion. The kinetics of the oxygen reduction reaction
is slower than that of the anode reaction, and at the same time, the potential on
the electrode such as Pt is higher, which makes the active metal or carrier on the
Z. Zhao
Research Institute of Tsinghua University in Shenzhen, Shenzhen, Guangdong, China
P. K. Shen (B)
Collaborative Innovation Center of Sustainable Energy Materials, Guangxi Key Laboratory of
Electrochemical Energy Materials, College of Chemistry and Chemical Engineering, Guangxi
University, Nanning, Guangxi 530004, China
e-mail: pkshen@gxu.edu.cn
© Guangxi Science & Technology Publishing House 2021
P. K. Shen, Electrochemical Oxygen Reduction,
https://doi.org/10.1007/978-981-33-6077-8_2
11