Biomedical Engineering Reference
In-Depth Information
Fig. 5.2
Electrochemistry at a CVD graphene electrode.
a
Cyclic voltammograms of FcMeOH
(1 mM) in H
2
O/0.1 M KCl measured at a CVD graphene electrode at different potential scan
rates.
Inset
plot of the anodic peak current (
ip
) versus the square root of the potential scan rate
(
v
1/2
).
b
Peak separation
Δ
Ep
and Nicholson's kinetic parameter
ψ
versus the reciprocal of the
square root of the potential scan rate (
v
-1/2
). A linear fit is used to determine the standard hetero-
geneous charge transfer rate constant (
k
0). Reproduced with permission from Ref. [
9
]. Copyright
2011, American Chemical Society
Afterward, Robert's group [
10
] researched the electrochemical properties of the
exfoliated single and multilayer graphene flakes to measure the rate constant for
electron transfer. Mechanical exfoliated graphene flakes were deposited on silicon/
silicon oxide wafers to make the masked graphene/graphite samples as the work-
ing electrode. They found that both multilayer and monolayer graphene microe-
lectrodes showed quasi-reversible behavior during voltammetric measurements in
potassium ferricyanide.
In recent years, graphene as a new class of two-dimensional nanomaterial has
attracted considerable attention. The excellent electronic transfer rate, single-
layered structure, and good biocompatibility endow graphene with great potential
applications in the field of electrocatalytic biodevices [
11
-
13
]. Wang's group [
14
]
reported on the utilization of graphene-CdS nanocomposite as a novel immobi-
lization matrix for the GOD immobilization. The nanocomposite could provide a
unique microenvironment for the direct electrochemistry of GOD, and the immo-
bilized GOD on the modified electrode possessed its native structure and electro-
catalytic activities. In comparison with the graphene sheets and CdS nanocrystals,
the graphene-CdS nanocomposites exhibited excellent electron transfer properties
for GOD with a rate constant (
k
s
) of 5.9 s
−
1
due to the synergy effect of graphene
