Introduction reaction (Bernard S. Finn, Curator, 1999). The anode

Introduction

         A fuel cell is an
electrochemical cell that converts chemical energy into
electricity through an electrochemical reaction of hydrogen fuel with
oxygen or another oxidizing agent and a catalyst (Fuel cell, 2017). It
is a lot like a battery; just like batteries, a fuel cell has two electrodes
and the reactions take place and an electrolyte; which carries the charged
particles from one electrode to the other. In order for a fuel cell to work, it
needs hydrogen (H2),
oxygen (O2)
and a catalyst. (Brian Marshall,2002). Fuel
cells are extremely useful when it comes to the production of electricity; they can be used in a number of applications including
transportation, material handling, stationary, portable, and emergency backup
power applications (Energy Gov.). Although fuel cells are useful to the society, they are prone to
catching on fire and maybe exploding and most importantly are very costly to
produce and difficult to store (July 23, 2015 Crystal Lombardo). A lot of engineers all over the world are trying to
solve this problem and make fuel cells cheaper and more durable to be used. Apart
from cost and storage fuel cells require expensive materials such as platinum use
at the electrode as a catalyst.

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(Justin
Wick, 2006)

How do fuel cells work?

             Using a process called
electrolysis, hydrogen atoms
enter a fuel cell at the anode where a chemical reaction strips them of their
electrons. The hydrogen atoms then become ionized. The negatively charged
electrons provide the current through wires to do work. If alternating current
(AC) is needed, the DC output of the fuel cell must be routed through a
conversion device called an inverter. Oxygen enters the fuel cell at the
cathode (I come cell types) and, it then combines with electrons returning from
the electrical circuit and hydrogen ions that have traveled through the
electrolyte from the anode. In other cell types the oxygen picks up electrons
and then travels through the electrolyte to the anode, where it combines with
hydrogen ions. The electrolyte plays a key role. It must
permit only the appropriate ions to pass between the anode and cathode. If free
electrons or other substances could travel through the electrolyte, they would
disrupt the chemical reaction (Bernard S. Finn, Curator, 1999). The anode is usually a platinum catalyst,
which causes the hydrogen to split into positive hydrogen ions (protons) and
negative hydrogen ions.

 

About the application, advantages and
concerns

               Since platinum is usually
expensive, costing around $30,000 per kilogram (Science Daily

2017,
September 5), scientists have potentially found
ways to reduce this cost. This is done using nanotechnology.

               The method that I have written
and researched on is the use of carbon, or
nanostructures like carbon nanotubes or nanowalls to further decrease the
amount of the expensive metal (platinum) which is needed to make an effective
catalytic electrode (cathode) (Will Soutter, 2012). A group of scientists have created
a new and improved fuel-cell electrode that is very lightweight and thin. It is
composed of a network of single-walled carbon nanotubes, with the electrode
functions nearly as well as conventional electrodes but renders the entire fuel
cell much lighter. The research is an important step toward lightweight power
supplies, which are becoming necessary, as electronic devices get ever smaller
and more streamlined (Physics org, 2008).    

                 Using carbon nanotubes have number
of superior properties than the use of platinum; these include electrical
conductivity, thermal conductivity, mechanical strength, and the ability to
support catalysts by providing an increased surface area, as well as a cheaper
cost. They are also used as an electrode replacement. The way in which
this works is that these carbon nanotubes are
doped with nitrogen.

                There are different methods
uses to make carbon nanaotubes, but the one I am explaining is a method called
the Arc method. This method
creates CNTs
(Carbon nanotubes) through arc-vaporization
of two carbon rods placed end to end, separated by approximately 1mm, in an
enclosure that is usually filled with inert gas (helium, argon) at low pressure
(between 50 and 700 mbar). Recent investigations have shown that it is also possible
to create CNTs with the arc method in liquid nitrogen. A direct
current of 50 to 100 A, driven by a potential difference of approximately 20 V,
creates a high temperature discharge between the two electrodes. The discharge
vaporizes the surface of one of the carbon electrodes, and forms a small
rod-shaped deposit on the other electrode. Producing CNTs in high yield depends on the uniformity of the
plasma arc, and the temperature of the deposit forming on the carbon electrode
(P. Vaughn, 2011).

                Despite the benefits of the of
carbon nanotubes as electrodes in fuel cells, there are some drawbacks with
using carbon nanoparticles: scientists still don’t fully understand exactly
how they work, they extremely small and therefore difficult to work with,
currently, the process is relatively expensive to produce the nanotube and
would be expensive to implement this new technology in and replace the older
technology in all the places that we could (P. Vaughn, 2011).
They also pose some health concerns. A new
doctoral dissertation at Luleå University of Technology in Sweden shows that
extremely small fibers such as carbon nanotubes can make their way far into the
lungs, which in the worst case can present an increased risk of developing
cancer. (Luleå: university of Technology. 2011, January 19)

 

 

 

Conclusion

        The use of carbon nanoparticles as an
alternative catalyst for fuel cells reactions has been seen as overall
beneficial however, there is some concerns about this concept. It is not fully
understood by scientist and some of the cost and concerns seem to potentially
overcome its benefits. Despite this, in the long term replacing the catalyst
platinum with carbon nanotubes would not only be effective in the production of
energy but also economically and environmentally efficient.