82
C. Juhong et al.
power of hydrogen to characterize the active area may be the only effective
method to characterize the active area of the metal.
In summary, hydrogen desorption and desorption characterizes the active area due
to its own premise, which makes it more uncertain, but its operation is simple and
can be detected in situ, so it is still a valuable test method.
After obtaining the electrochemical specific surface area, if the net kinetic current
i k is known, the specific activity is further determined. For the activity of the catalyst
to be characterized by specific activity, it is necessary to pay attention to the fact
that, from the formula, to increase the specific activity, since the increase of the net
kinetic current is generally difficult to keep up with the increase of the active area,
there are two options, which are greatly reduced. The active area or the net kinetic
current is greatly increased. Since the active area can be made very large under normal
circumstances, and the increase of the net kinetic current is very small, in many cases,
the experimental result is to increase the specific surface area several times, but the
specific activity does not increase or even decrease. However, as far as we know, in
general, the larger the specific surface area, the higher the utilization rate of the noble
metal in the catalyst, and the increase of the specific surface area is advantageous
for increasing the utilization rate of the active material of the catalyst and thereby
improving the catalytic activity of the oxygen reduction. However, using this activity
standard, the most common case is to reduce the active area or the catalyst utilization
is beneficial to increase the specific activity, thereby optimizing the oxygen reduction
catalytic activity, which is contrary to our research common knowledge. The U.S.
Department of Energy has been aware of this problem and has removed the activity
standard for activity than the latest DOE indicator.
References
1. Teliska A, O’Grady WE, Ramaker DE (2005) Determination of O and OH adsorption sites and
coverage in situ on Pt electrodes from Pt L23 X-ray absorption spectroscopy. J Phys Chem B
109:8076
2. Murthi VS, Urian RC, Mukerjee S (2004) Oxygen reduction kinetics in low and medium temperature acid environment: correlation of water activation and surface properties in supported Pt
and Pt alloy electrocatalysts. J Phys Chem B 108:11011
3. Roth C, Benker N, Buhrmester T et al (2005) Determination of O[H] and CO coverage and
adsorption sites on PtRu electrodes in an operating PEM fuel cell. J Am Chem Soc 127:14607
4. Teliska M, Murthi VS, Mukerjee S et al (2005) Correlation of water activation, surface properties, and oxygen reduction reactivity of supported Pt–M/C bimetallic electrocatalysts using
XAS. J Electrochem Soc 152:A2159
5. Koh S, Leisch J, Toney MF et al (2007) Structure-activity-stability relationships of Pt−Co
alloy electrocatalysts in gas-diffusion electrode layers. J Phys Chem C 111:3744
6. Koh S, Toney MF, Strasser P (2007) Activity–stability relationships of ordered and disordered
alloy phases of Pt3Co electrocatalysts for the oxygen reduction reaction (ORR). Electrochim
Acta 52:2765
7. Yano H, Inukai J, Uchida H et al (2006) Particle-size effect of nanoscale platinum catalysts in
oxygen reduction reaction: an electrochemical and 195Pt EC-NMR study. Phys Chem Chem
Phys 8:4932
C. Juhong et al.
power of hydrogen to characterize the active area may be the only effective
method to characterize the active area of the metal.
In summary, hydrogen desorption and desorption characterizes the active area due
to its own premise, which makes it more uncertain, but its operation is simple and
can be detected in situ, so it is still a valuable test method.
After obtaining the electrochemical specific surface area, if the net kinetic current
i k is known, the specific activity is further determined. For the activity of the catalyst
to be characterized by specific activity, it is necessary to pay attention to the fact
that, from the formula, to increase the specific activity, since the increase of the net
kinetic current is generally difficult to keep up with the increase of the active area,
there are two options, which are greatly reduced. The active area or the net kinetic
current is greatly increased. Since the active area can be made very large under normal
circumstances, and the increase of the net kinetic current is very small, in many cases,
the experimental result is to increase the specific surface area several times, but the
specific activity does not increase or even decrease. However, as far as we know, in
general, the larger the specific surface area, the higher the utilization rate of the noble
metal in the catalyst, and the increase of the specific surface area is advantageous
for increasing the utilization rate of the active material of the catalyst and thereby
improving the catalytic activity of the oxygen reduction. However, using this activity
standard, the most common case is to reduce the active area or the catalyst utilization
is beneficial to increase the specific activity, thereby optimizing the oxygen reduction
catalytic activity, which is contrary to our research common knowledge. The U.S.
Department of Energy has been aware of this problem and has removed the activity
standard for activity than the latest DOE indicator.
References
1. Teliska A, O’Grady WE, Ramaker DE (2005) Determination of O and OH adsorption sites and
coverage in situ on Pt electrodes from Pt L23 X-ray absorption spectroscopy. J Phys Chem B
109:8076
2. Murthi VS, Urian RC, Mukerjee S (2004) Oxygen reduction kinetics in low and medium temperature acid environment: correlation of water activation and surface properties in supported Pt
and Pt alloy electrocatalysts. J Phys Chem B 108:11011
3. Roth C, Benker N, Buhrmester T et al (2005) Determination of O[H] and CO coverage and
adsorption sites on PtRu electrodes in an operating PEM fuel cell. J Am Chem Soc 127:14607
4. Teliska M, Murthi VS, Mukerjee S et al (2005) Correlation of water activation, surface properties, and oxygen reduction reactivity of supported Pt–M/C bimetallic electrocatalysts using
XAS. J Electrochem Soc 152:A2159
5. Koh S, Leisch J, Toney MF et al (2007) Structure-activity-stability relationships of Pt−Co
alloy electrocatalysts in gas-diffusion electrode layers. J Phys Chem C 111:3744
6. Koh S, Toney MF, Strasser P (2007) Activity–stability relationships of ordered and disordered
alloy phases of Pt3Co electrocatalysts for the oxygen reduction reaction (ORR). Electrochim
Acta 52:2765
7. Yano H, Inukai J, Uchida H et al (2006) Particle-size effect of nanoscale platinum catalysts in
oxygen reduction reaction: an electrochemical and 195Pt EC-NMR study. Phys Chem Chem
Phys 8:4932