hydrogen production from water using solar cells powered nafion ...

itself. The design minimizes the electrical resistances since the reaction occurs on both
surface of the membrane due to the presence of the catalyst.
The definitions of anode and cathode electrodes are as follows; anode is “the
electrode in a device that electrons flow out to return to the circuit” and the definition of
cathode is “the electrode at which electrons go into a cell, tube or diode, whether driven
externally or internally”. According to that, the cathode of the fuel cell is the side where
water composes (oxygen side) and anode is the hydrogen inlet side. Though according to
definition of cathode is the hydrogen generation side and anode is the side where water
decomposes (Larminie and Dicks 2003).
Although PEM electrolyzer and PEM fuel cells seem similar devices they have
significant differences such as, catalyst loadings and support material of their electrodes.
Fabrication of membrane electrode assemblies for PEM electrolysis requires additional
effort since duties of their electrodes are different than PEM fuel cell electrodes. The
electrode in a fuel cell is used to expel the product water and to draw the reactant gases as
quickly as possible whereas the idea behind an electrolyzer electrode is to draw the water
and expel the gases as quickly as possible.
There are two alternative routes for the electrode fabrication used in PEM fuel cell
and PEM electrolysis. First method is the separate electrode method which carbon
supported catalyst is fixed with various techniques to a porous and conductive material,
such as carbon cloth or carbon paper. Polytetrafluoroethylene (PTFE) is often be added for
the fuel cell cathodes because it is hydrophobic and expels the product water (Larminie and
Dicks 2003). The carbon paper cloth is also used to diffuse the gas through its pores onto
the catalyst surface, which is called as the gas diffusion layer. Two similar electrodes are
then fixed to each side of the proton exchange membrane (Larminie and Dicks 2003). The
second method is to build electrodes directly onto the membrane. The catalyst is applied to
the electrolyte with the methods, such as mechanical pressing, hot pressing, decal transfer,
coating or clamping of precursors sol-impregnated electrode (Thangamuthu and Lin 2005).
These fabrication approaches are used to achieve a good conduction of the catalyst surface
with the proton exchange membrane which increases the effectiveness of the cell per unit
mass of the catalyst. Although these methods are used for electrolysis MEA fabrication,
catalyst and support materials may change in the electrolysis case, for example the
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