Page 57 - MODERN ELECTROCHEMISTRY

2 CHAPTER 1

Take another gigantic leap along the timeline of electrochemical discovery and
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application. Consider Michael Faraday, that London superstar who in 1834 discov-
ered the relation between the amount of electricity consumed and the amount of metal
produced in solid form from some invisible particles in solution. In 1995, more than
a century later, Despic and Popov wrote an article that described electroforming of
(almost) anything from its ion in solution: powders or dendrites, whiskers or pyramids,
in laminar shapes of any chosen composition (including that of semiconductors) or
indeed in nanometer sizes. This is what has become of Faraday’s electrodeposition at
the cutting edge, as well as in practical applications such as electrodissolution to shape
metal parts in the making of Rolls Royce cars.
Of all these jumps in electrochemistry, each separated by around a century, there
is one that best of all shows how electrochemistry is both deep-rooted and at the frontier
of the twenty-first century. It was the pedant Julius Tafel who found, in 1905, that
electric currents passing across metal–solution interfaces could be made to increase
exponentially by changing the electric potential of the electrode across the surface of
which they passed. In this way, he complemented the finding in ordinary kinetics made
by Arrhenius 16 years earlier. Arrhenius’s equation tells us that an increase of
temperature increases the rate of chemical reaction exponentially:

where A and are constants, with representing the activation energy.
Corresponding to this, Tafel found a similar equation:

where B, and F are constants. The term (a constant times a potential V times
a quantity of electricity F) represents energy; one can see that the two equations are
related.
To what did Tafel’s discovery lead in our lifetime? To the first moon landing in
1969! In the 64 years from Tafel’s discovery of how electrochemical reaction rates
vary with potential, it had become possible to take his equation and use it in the
development of an electrochemical fuel cell that produced electricity from chemicals
directly without moving parts. This was firstly done by Groves in 1939. Those 64 years
following Tafel’s discovery had been well used, particularly at Cambridge University
in England, by Tom Bacon (a descendant of the seventeenth-century Bacon, Baron
Verulam, whom some see as the founder of Science as we know it). Tom Bacon
established in practice what theorists had for long reasoned: that the electrochemical
fuel cell produced electrical energy from chemical fuels at twice the efficiency of a

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Despite his achievements, Faraday was subject to the whip of religious discipline. When he accepted an
invitation to visit Buckingham Palace to receive an award from Queen Victoria, and missed a religious
service, his church told him that he had preferred Mammon to God and ought to leave the church!