Chemistry Reference
In-Depth Information
6.12.2.1 Electrochemical Features and
Application to Highly Sensitive
Electroanalysis
Wide Potential Window in Aqueous
Solution
[101,102]
:
BDD electrodes have a
hydrogen overpotential at about −1 V vs. Ag/
AgCl, which is comparable to mercury, and an
oxygen overpotential at about +2.2 V vs. Ag/
AgCl, which is higher than other common
anode materials. Its potential window is
therefore as wide as 3.2 V and this is a
pronounced feature of the BDD electrode. Even
in aprotic organic solvents like MeCN, the
cathodic window is about 500 mV wider than
that of a Pt electrode. Accordingly, such unique
properties could result in replacement of either
costly noble metals or toxic heavy metals.
Small Background Current (Small
Residual Current Density)
[101,102]
:
The
capacitance of the BDD electrode surface is a
few mF cm
−2
, which is two orders smaller
compared to glassy carbon, and its residual
current density is as small as a few hundred nA
cm
−2
. This is attributable to the fact that
neither dissolved gas nor ions of supporting salt
adsorb on the BDD surface, making redox
reactions difficult.
Large Overpotential of Oxygen
Reduction
[103]
:
Because of the difficult
cathodic reduction of dissolved oxygen, the
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