European Journal of Scientific Research - EuroJournals

399 R. Y. Tamakloe, K. Singh and Clovis A. Linkous
2.1. Preparation of PEM film
The PEM film was prepared for catalyst application by dipping the membrane in six different heated
solutions in glass beakers. The solutions were all held between 80ºC and 85ºC by immersing the
beakers in an ultrasonic washer containing heated water. The bath is heated by means of an immersion
heater. Each beaker held the PEM for 30 minutes in sequence. The sequence of beakers used was set
up as follows:
Beaker 1 –> 150 ml of distilled water to hydrate the membrane and dissolve surface
contaminants.
Beaker 2 -> 150 ml of 3% hydrogen peroxide solution to remove organic contaminants from
the PEM surface.
Beaker 3 -> 150 ml of sulfuric acid (new battery electrolyte) to remove metal ion contaminants
from the PEM surface, and sulfonate the PEM surface.
Beaker 4 -> 150 ml of distilled water to rinse sulfuric acid from the surface and hydrate the
PEM.
Beaker 5 -> 150 ml distilled water to repeat rinse.
Beaker 6 -> 150 ml distilled water repeat rinse.
A mercury thermometer was used for checking the beaker bath temperature. From time to time,
more water had to be added to the bath surrounding the beakers, due to evaporation. The ultrasonic
action quickens the washing process. After the PEM disk was dipped in each of the six hot solution
beakers for 30 minutes, it was then air-dried in a clean place (Pyle W., et al, 2003).
2.2. Hot-Pressing the Sandwich Together
Two sheets, 3 cm by 5.5 cm were cut from the platinum-carbon impregnated sheet to serve as
electrodes. A membrane of 5 cm by 7 cm was also cut. A hot press was made using a workshop vice
and two metallic containers, each 200 cm 3 capable of holding the immersion heater, shown below.
Since water is the heating medium the highest temperature attained was 100ºC.
First, the surfaces of the heating containers in contact with the catalyst were coated with
graphite from a 2B pencil. The three layers, catalyst-PEM-catalyst, of the sandwich were then set in
between the two heating containers. The layers were carefully aligned so that the smaller catalyst disks
were centered above and below the larger PEM disk. At this time the heaters were turned off and the
plates let cool to room temperature. Next, the two temperature controllers were initiated and the
sandwich was taken up to 100ºC for one hour. Once the heating plates and the sandwich reached
100ºC, pressure was applied by tightening the vice. After this time the heater was turned off and the
plates and sandwich cooled to room temperature. The heating containers were opened, and the finished
fuel cell sandwich was removed using the tweezers.
The PEM sandwich was placed between two aluminum meshes to enable external electrical
connection, thus forming the Al/xxx/Al cell. The five-layered sandwich was then placed in between
machined transparent Acrylic blocks. The indenture retains the passing fuel for enough time to allow
for absorption or consumption. An Al/xxx/Cu was also fabricated and tested.
3.0. Results
The measured values of current and voltages for Al/xxx/Al and Al/xxx/Cu
Cells are presented in Table 1 and Table 2 respectively.