This minireview discusses the current on-demand applications of the conductive 3D-printed electrodes based upon polymer/carbon nanomaterial filaments, printed using the FDM 3D printing method, in developing electrochemical sensors and biosensors.
Electrodeposition
is an electrochemical method employed to deposit
stable and robust gold nanoparticles (AuNPs) on electrode surfaces
for creating chemically modified electrodes (CMEs). The use of several
electrodeposition techniques with different experimental parameters
allow in obtaining various surface morphologies of AuNPs deposited
on the electrode surface. By considering the electrodeposition of
AuNPs in various background electrolytes could play an important strategy
in finding the most suitable formation of the electrodeposited AuNP
films on the electrode surface. This is because different electrode
roughnesses can have different effects on the electrochemical activities
of the modified electrodes. Thus, in this study, the electrodeposition
of AuNPs onto the glassy carbon (GC) electrode surfaces in various
aqueous neutral and acidic electrolytes was achieved by using the
cyclic voltammetry (CV) technique with no adjustable CV parameters.
Then, surface morphologies and electrochemical activities of the electrodeposited
AuNPs were investigated using scanning electron microscopy (SEM),
atomic force microscopy (AFM), CV, and electrochemical impedance spectroscopy
(EIS). The obtained SEM and 3D-AFM images show that AuNPs deposited
at the GC electrode prepared in NaNO3 solution form a significantly
better, uniform, and homogeneous electrodeposited AuNP film on the
GC electrode surface with nanoparticle sizes ranging from ∼36
to 60 nm. Meanwhile, from the electrochemical performances of the
AuNP-modified GC electrodes, characterized by using a mixture of ferricyanide
and ferrocyanide ions [Fe(CN6)3–/4–], there is no significant difference observed in the case of charge-transfer
resistances (R
ct) and heterogeneous electron-transfer
rate constants (k
o), although there are
differences in the surface morphologies of the electrodeposited AuNP
films. Remarkably, the R
ct values of the
AuNP-modified GC electrodes are lower than those of the bare GC electrode by 18-fold, as the R
ct values were found to be ∼6 Ω (p < 0.001, n = 3). This has resulted
in obtaining k
o values of AuNP-modified
GC electrodes between the magnitude of 10–2 and
10–3 cm s–1, giving a faster electron-transfer
rate than that of the bare GC electrode (10–4 cm
s–1). This study confirms that using an appropriate
supporting background electrolyte plays a critical role in preparing
electrodeposited AuNP films. This approach could lead to nanostructures
with a more densely, uniformly, and homogeneously electrodeposited
AuNP film on the electrode surfaces, albeit utilizing an easy and
simple preparation method.
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