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J. Zhu et al.
6.1.1 The Peak Potential
For a single fuel cell (E = E cathode – E anode ), the higher the peak potential of oxygen
reduction, the better. The peak potential of oxygen reduction mainly depends on the
catalyst material itself (catalyst type).
In acidic media, although many nonplatinum catalysts, such as metal carbides,
metal sulfides, metal selenides, M-N x /C (M = Fe or Co) and heteroatom-doped
carbon materials have been reported, their peak potentials are generally lower than
platinum catalysts. In 2006, Huamin Zhang’s group reported that Mo 2 N catalyst
demonstrated the oxygen reduction peak potential of 0.46 V versus SCE in 0.5 mol/L
sulfuric acid solution [1]. In the study of Akimitsu Ishihara’s group in 2012, the peak
potential of oxygen reduction in 0.1 mol/L sulfuric acid solution was 0.5–0.6 V versus
RHE. The oxygen reduction peak potential of Ta-CO obtained from TaC was 0.8 V
versus RHE [2]. In 2010, Pei Kang Shen’s and Shuhong Yu’s group reported that the
oxygen reduction peak potential of porous Co 9 S 8 spheres in 0.5 mol/L sulfuric acid
solution was 0.74 V versus RHE [3]. In 2008, Nicolas Alonso-Vante reported that
the oxygen reduction peak potential of carbon-loaded Co 3 S 4 in 0.5 mol/L sulfuric
acid solution was 0.66 V versus RHE [4]. In 2011, Hongjie Dai’s group at Stanford
University studied the oxygen reduction performance of Co 1-x S/graphene and found
that Co 1-x S had the highest activity among the reported cobalt sulfide catalysts of
oxygen reduction, showing the peak potential of 0.8 V versus RHE in 0.5 mol/L
sulfuric acid solution [5].
Due to the combination of lone pair electrons of nitrogen atoms in nitrogendoped carbon materials and π electron system on the surface of graphitized carbon
materials, the reconfiguration of carbon atoms and the formation of local defects
produce oxygen reduction activity [6], and it is one of the most promising materials in nonprecious metal catalysts. Nitrogen-doped carbon materials have the same
peak potential of oxygen reduction as Pt in alkaline media. In 2009, the group of
Liming Dai found that when nitrogen-doped carbon nanotube array was used as an
oxygen reduction catalyst, it had almost the same peak potential of Pt/C catalyst
in 0.1 mol /L KOH [7]. Afterward, a large number of experimental studies showed
that the peak potential of oxygen reduction of nitrogen-doped carbon materials such
as nitrogen-doped carbon nanotubes, nitrogen-doped graphene and nitrogen-doped
graphite cage in alkaline media was equivalent to that of Pt/C catalyst. In 2010,
Wolfgang Schuhmann’s group in Germany [8] reported that nitrogen-doped carbon
nanotubes (NCNT-800) obtained by heat treatment of carbon nanotubes at 800 °C
under ammonia gas had a peak potential of 0.06 V (vs. Ag/AgCl/3 M KCl) and
which was higher than that of commercial Pt/C in 1 mol/L sodium hydroxide solution. In 2011, Xueliang Sun’s group in Canada [9] used ammonia gas at 900°C to
heat treat graphene to obtain nitrogen-doped graphene N-graphene (900), the peak
potential of oxygen reduction of in 0.1 mol/L potassium hydroxide solution was
0.308v (vs. SHE). It is more positive than the peak potential of oxygen reduction
measured by commercial Pt/C (E-TEK) under the same experimental conditions.
In 2012, Xizhang Wang research group of Nanjing University of China [10] used
J. Zhu et al.
6.1.1 The Peak Potential
For a single fuel cell (E = E cathode – E anode ), the higher the peak potential of oxygen
reduction, the better. The peak potential of oxygen reduction mainly depends on the
catalyst material itself (catalyst type).
In acidic media, although many nonplatinum catalysts, such as metal carbides,
metal sulfides, metal selenides, M-N x /C (M = Fe or Co) and heteroatom-doped
carbon materials have been reported, their peak potentials are generally lower than
platinum catalysts. In 2006, Huamin Zhang’s group reported that Mo 2 N catalyst
demonstrated the oxygen reduction peak potential of 0.46 V versus SCE in 0.5 mol/L
sulfuric acid solution [1]. In the study of Akimitsu Ishihara’s group in 2012, the peak
potential of oxygen reduction in 0.1 mol/L sulfuric acid solution was 0.5–0.6 V versus
RHE. The oxygen reduction peak potential of Ta-CO obtained from TaC was 0.8 V
versus RHE [2]. In 2010, Pei Kang Shen’s and Shuhong Yu’s group reported that the
oxygen reduction peak potential of porous Co 9 S 8 spheres in 0.5 mol/L sulfuric acid
solution was 0.74 V versus RHE [3]. In 2008, Nicolas Alonso-Vante reported that
the oxygen reduction peak potential of carbon-loaded Co 3 S 4 in 0.5 mol/L sulfuric
acid solution was 0.66 V versus RHE [4]. In 2011, Hongjie Dai’s group at Stanford
University studied the oxygen reduction performance of Co 1-x S/graphene and found
that Co 1-x S had the highest activity among the reported cobalt sulfide catalysts of
oxygen reduction, showing the peak potential of 0.8 V versus RHE in 0.5 mol/L
sulfuric acid solution [5].
Due to the combination of lone pair electrons of nitrogen atoms in nitrogendoped carbon materials and π electron system on the surface of graphitized carbon
materials, the reconfiguration of carbon atoms and the formation of local defects
produce oxygen reduction activity [6], and it is one of the most promising materials in nonprecious metal catalysts. Nitrogen-doped carbon materials have the same
peak potential of oxygen reduction as Pt in alkaline media. In 2009, the group of
Liming Dai found that when nitrogen-doped carbon nanotube array was used as an
oxygen reduction catalyst, it had almost the same peak potential of Pt/C catalyst
in 0.1 mol /L KOH [7]. Afterward, a large number of experimental studies showed
that the peak potential of oxygen reduction of nitrogen-doped carbon materials such
as nitrogen-doped carbon nanotubes, nitrogen-doped graphene and nitrogen-doped
graphite cage in alkaline media was equivalent to that of Pt/C catalyst. In 2010,
Wolfgang Schuhmann’s group in Germany [8] reported that nitrogen-doped carbon
nanotubes (NCNT-800) obtained by heat treatment of carbon nanotubes at 800 °C
under ammonia gas had a peak potential of 0.06 V (vs. Ag/AgCl/3 M KCl) and
which was higher than that of commercial Pt/C in 1 mol/L sodium hydroxide solution. In 2011, Xueliang Sun’s group in Canada [9] used ammonia gas at 900°C to
heat treat graphene to obtain nitrogen-doped graphene N-graphene (900), the peak
potential of oxygen reduction of in 0.1 mol/L potassium hydroxide solution was
0.308v (vs. SHE). It is more positive than the peak potential of oxygen reduction
measured by commercial Pt/C (E-TEK) under the same experimental conditions.
In 2012, Xizhang Wang research group of Nanjing University of China [10] used