Electrochemical Preparation of Polyaniline/Gold Film
Johnson Agyapong1, Antony Epps2, Kenton Meronard3, and Amir Saheb, PhD3
1Brandeis University, 2South Side Virginia Community College, 3Albany State University
• Phase 2
After PANI has been electropolymerized, the deposition of gold the film begins. A bulk
electrolysis is run in 1M HCl at 0.7V for 40s to oxidize PANI and then rinsed with 1M HCl
and dipped in 10-5M HAuCl4 containing 1M HCl for 30s. The film is rinsed again with 1M
HCl and a linear sweep is run at 0.7 V to -0.2 V at a scan rate of 20 mV/s to reduce it. A
CHI Instruments potentiostat alongside a UV-Vis spectrophotometer to characterize the
PANI/Au film after each gold deposition.
The PANI/Au films were made in two phases:
Phase1: Electropolymerization of polyaniline
Phase2: Gold Deposition
Using a three compartment electrochemical cell made up of Ag/AgCl reference electrode, Pt
or ITO working electrode, and Pt wire or foil counter electrode, PANI was deposited on an
ITO substrate or platinum electrode by CV from 0.1M aniline and 1M H2S04 solution within a
range of -0.2V to +0.8V. The CV was run for 25 cycles (50 segments) at 20 mV/s.
Dey, A., Kaushik, A., Arya, S., & Bhansali, S. (2012). Mediator free highly sensitive
polyaniline-gold hybrid nanocomposite based immunosensor for prostate-specific antigen
(PSA) detection. Journal Of Materials Chemistry, 22(29), 14763-14772.
Saheb, A., & Seo, S. (2011). Polyaniline/Au Electrodes for Direct Methanol Fuel Cells.
Analytical Letters, 44(12), 2221-2228.
Saheb, A., Smith, A., Josowicz, M., Janata, J., Baer, DR., & Engelhard, MH. (2008).
Controlling size of gold clusters in polyaniline from top–down and from bottom–up. Journal of
Electroanalytical Chemistry, 621(2), 238-244.
Shin, L., (2008). Gold Nanoparticles. Retrieved from
Song, E., & Choi JW. (2013). Conducting Polyaniline Nanowire and Its Applications in
Chemiresistive Sensing. Nanomaterials.
Surwade, S., & Manohar, Sanjeev K. (2010). Synthesis of Nanostructured
Polyaniline,ProQuest Dissertations and Theses.
We would like to say a special thank you to Dr. Amir Saheb and Kenton Meronard for
helping us through our research. We also thank Dr. Samuel and the whole PREM faculty
for making this experience enjoyable.
PANI can be labeled scientist’s favorite conducting polymer because its synthesis is fairly
easy and the oxidation states of PANI can be manipulated by changing oxidation/reduction.
Its versatility makes its applications endless. One of the applications of PANI is creation of
electrochemical biosensors which was what we were ultimately trying to create by attaching
gold using the bottom up approach. Gold increases the catalytic properties of PANI. Saheb &
Seo observed an increase in the oxidation of PANI in methanol once Au atoms were attached
(2011). Dey et al. utilized PANI/Au nanoparticles as an immunosensor for prostate-specific
antigen and found that there was an increase in sensing performance (2012). Also, they found
that Au nanoparticles increased the “electro-active surface area of PANI” (2012) making
PANI/Au films favorable components of a biosensor. Gold has a high affinity to thiol groups
so by attaching a thiolated DNA probe, we come up with a sensitive and highly specific DNA
The objective of this project is to utilize this technology to develop and synthesize our own
Polyaniline (PANI) is a conductive polymer produced by polymerizing aniline. Owing to
favorable properties like easy synthesis and ability to change oxidation state with simple
oxidation/reduction (Surwade, 2010), there have been numerous research projects based on
the potential applications of PANI. Aniline can be polymerized chemically or
electrochemically; however, the latter was utilized in this experiment because the final
product did not require extraction from any solvent, oxidant or monomer (Chemistry of
polyaniline). Our short-term goal was to deposit gold clusters on the PANI film and
potentially create a DNA hybridization biosensor. We successfully electropolymerized
polyaniline on ITO substrates and platinum (Pt) electrodes but we were unable to achieve our
short-term goal. We went through up to 8 gold treatments but our methods of characterization
could not detect any gold present on the PANI film. We believe that gold clusters were
present but too tiny to be detected by our methods of characterization. Saheb et al, note that
such gold clusters may be detected using XPS (2008).
Presence of polyaniline can be observed with the naked eye. It has a greenish color
which changes to different shade of green as the oxidation state changes. For the
PANI/Au film, we used CHI instrument potentiostat and UV-Vis spectrophotometer to
characterize our film. Saheb & Seo (2011) observed an increase the oxidation of
PANI/Au compared with plain PANI in methanol. So we run CV in 0.5M H2SO4
containing 1M CH3OH to observe the oxidation of PANI/Au. We also used UV-Vis
spectrophotometer which we run after the 0, 2, 5, and 7 gold treatments.
Scheme 1. Setup of phase 1
Scheme 2. Cycle of phase 2 beginning from Bulk Electrolysis. Each cycle
represents deposition of one Au atom.
Figure 1: (a) CV of PANI
formation, (b -d) Morphology
of PANI using SEM.
Figures 3: (Right) PANI/Au film UV-Vis Spectra after 0, 2, 5 and 7 Au treatments (Left)UV-
Vis Spectra after 0, 1, 3 and 5 Au treatments in both Oxidized and reduced states (Saheb &
• We were able to successfully synthesize and characterize the the PANI film onto both a 2
mm diameter Platinum surface and ITO (Indium Tin Oxide) Coated Glass.
• During electrochemical polymerization, We observed the three major oxidation peaks.
• Characterization of our samples using CV and UV-Vis was challenged due to the weak
bonding of the PANI film and the ITO surface.
• Despite this, data from UV-Vis and methanol oxidation, suggest that our films did not
contain Au clusters at detectable levels
(a) PANI after CV (38
cycles at 20mV/s),
(b) PANI in emeraldine
(c) PANI in