![](images/pres.png)
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The Preparation of the Samples
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The
negative electrode: a pure-lead sheet (99.99%);
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The electrolyte: sulfuric acid solution of 5M
concentration;
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Oxygen dissolved in the electrolyte was removed by
bubbling argon gas
for more than 2h beforehand;
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The lead surface was cleaned with acetic acid to
remove the existing
lead oxide layer, and then washed with ethanol;
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After preparing the surface of the electrode a
small amount of CaSO4 or Bi2(SO4)3
powder was pressed on the surface;
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A constant force was applied in order to
fix the sulfates on the
surface of the electrode;
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The Pb plate was placed in
a cell as the working electrode;
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In order to reduce any oxides on the lead surface
we applied a negative
potential on two steps;
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First we applied -1400 mV for 10 min and then -1200
mV for 10 min;
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