52
C. Juhong et al.
glassy carbon disk (platinum disk) electrode will be taken as an example to describe
the selection of the electrode and the preparation and coating of the catalyst layer.
Rotating disc (ring disc) electrodes operating under different test conditions
require special manufacture. Rotating disc (ring disc) electrodes manufactured by
Pine Instrument Company of the USA are of various types and are composed of
different materials. The glassy carbon ring electrode used for the oxygen reduction
test of the electrocatalytic system is composed of a glassy carbon disk electrode and
a platinum ring electrode. Ordinary rotating ring electrodes can be used at temperatures not higher than 30 °C and rotating at speeds not higher than 3,000 rpm. The
electrode working under high temperature conditions needs special production. The
key point is that the electrode does not seep at high temperature. This is because
the connecting wire in the electrode is a special metal material. Once the liquid is
exuded, the working electrode will become the metal. Electrode, not the electrode we
want to measure. Therefore, in order for the electrode to be liquid-free during operation, we need a special protective material which is equivalent to the coefficient of
thermal expansion between the electrodes. Typical rotating ring electrodes manufactured by Pine Instruments of the USA are AFE6R2/GC-Pt (see Fig. 3.5(c)I) for high
temperature use and AFE7R9/GC-Pt for ambient temperature (see Fig. 3.5(c)II). The
insulating material at room temperature is Teflon, and the high temperature insulating
material is PEEK.
The device for rotating the ring electrode is shown in Fig. 3.5. It consists of an
electric rotating system, an electrolytic cell system, a constant temperature system
(which maintains a constant oxygen solubility), and an electrochemical test instrument. Figure 3.5a shows the overall assembly drawing, Fig. 3.5b shows the study
electrode mounting, and Fig. 3.5c shows the ring disk electrode. When using, connect
the electrode to the rotating shaft Fig. 3.5b, and finally insert it into the electrolytic
cell.
In the new catalyst study, when the experimental instrument is ready, the catalytic
layer is prepared on the surface of the glassy carbon electrode. The following
describes the method for preparing the catalytic layer in our laboratory, as follows.
First, a small amount of catalyst sample was accurately weighed by an electronic
balance, dispersed in distilled water, ultrasonically shaken for 15 min, and then
centrifuged for 30 min until the catalyst and moisture layers were removed, and the
water was removed. This step was to clean the catalyst and reduce the influence of
impurities. The catalyst was then dispersed in water/alcohol, and a certain amount
of a 5% Nafion suspension solution (manufactured by DuPont, USA) was added,
and ultrasonically dispersed to prepare an ink-like slurry. The slurry should be well
dispersed and cannot be agglomerated or precipitated. A proper amount of slurry was
accurately transferred with a 25.0 μl micro-syringe, uniformly coated on the surface
of the electrode, and baked to dryness under an infrared lamp to form a uniform
thin layer of catalyst on the surface of the electrode. The general usage is 10μg Pt
cm
−2 –40 μg Pt cm
−2 .
It has been reported in the literature [7, 8] that the Pt/C layer with a glassy carbon
surface of less than 0.1 μm does not affect the distribution of oxygen on the electrode.
Intrinsically hydrophobic catalysts, as well as alcohol or high temperature treated
C. Juhong et al.
glassy carbon disk (platinum disk) electrode will be taken as an example to describe
the selection of the electrode and the preparation and coating of the catalyst layer.
Rotating disc (ring disc) electrodes operating under different test conditions
require special manufacture. Rotating disc (ring disc) electrodes manufactured by
Pine Instrument Company of the USA are of various types and are composed of
different materials. The glassy carbon ring electrode used for the oxygen reduction
test of the electrocatalytic system is composed of a glassy carbon disk electrode and
a platinum ring electrode. Ordinary rotating ring electrodes can be used at temperatures not higher than 30 °C and rotating at speeds not higher than 3,000 rpm. The
electrode working under high temperature conditions needs special production. The
key point is that the electrode does not seep at high temperature. This is because
the connecting wire in the electrode is a special metal material. Once the liquid is
exuded, the working electrode will become the metal. Electrode, not the electrode we
want to measure. Therefore, in order for the electrode to be liquid-free during operation, we need a special protective material which is equivalent to the coefficient of
thermal expansion between the electrodes. Typical rotating ring electrodes manufactured by Pine Instruments of the USA are AFE6R2/GC-Pt (see Fig. 3.5(c)I) for high
temperature use and AFE7R9/GC-Pt for ambient temperature (see Fig. 3.5(c)II). The
insulating material at room temperature is Teflon, and the high temperature insulating
material is PEEK.
The device for rotating the ring electrode is shown in Fig. 3.5. It consists of an
electric rotating system, an electrolytic cell system, a constant temperature system
(which maintains a constant oxygen solubility), and an electrochemical test instrument. Figure 3.5a shows the overall assembly drawing, Fig. 3.5b shows the study
electrode mounting, and Fig. 3.5c shows the ring disk electrode. When using, connect
the electrode to the rotating shaft Fig. 3.5b, and finally insert it into the electrolytic
cell.
In the new catalyst study, when the experimental instrument is ready, the catalytic
layer is prepared on the surface of the glassy carbon electrode. The following
describes the method for preparing the catalytic layer in our laboratory, as follows.
First, a small amount of catalyst sample was accurately weighed by an electronic
balance, dispersed in distilled water, ultrasonically shaken for 15 min, and then
centrifuged for 30 min until the catalyst and moisture layers were removed, and the
water was removed. This step was to clean the catalyst and reduce the influence of
impurities. The catalyst was then dispersed in water/alcohol, and a certain amount
of a 5% Nafion suspension solution (manufactured by DuPont, USA) was added,
and ultrasonically dispersed to prepare an ink-like slurry. The slurry should be well
dispersed and cannot be agglomerated or precipitated. A proper amount of slurry was
accurately transferred with a 25.0 μl micro-syringe, uniformly coated on the surface
of the electrode, and baked to dryness under an infrared lamp to form a uniform
thin layer of catalyst on the surface of the electrode. The general usage is 10μg Pt
cm
−2 –40 μg Pt cm
−2 .
It has been reported in the literature [7, 8] that the Pt/C layer with a glassy carbon
surface of less than 0.1 μm does not affect the distribution of oxygen on the electrode.
Intrinsically hydrophobic catalysts, as well as alcohol or high temperature treated