To install StudyMoose App tap and then “Add to Home Screen”
Save to my list
Remove from my list
This article presents the galvanostatic preparation of graphite supported PlatinumTin (PtSn) electrode for electrooxidation study. The electrode was characterized by SEM and
EDX. Investigation of electrooxidation of isopropanol onto Pt-Sn electrode was carried out by
applying cyclicvoltammetry technique at different scan rates. A three electrode setup was used
for this investigation. It is seen from the investigation that anodic peak potentials (1st and 2nd
oxidation peak) as well as the corresponding peak currents changed with scan rate.
Keywords : Isopropanol, elctrooxidation, cyclicvoltammetry.
The kinetics of electrochemical oxidation of small organic molecules is of fundamental importance in
electrocatalysis and is also a vital factor in the application in fuel cells.
Now aliphatic alcohols have been
promoted as promising fuels for direct alcohol fuel cells (DAFCs) in particular ethanol and propanol [1]. This is
due to the better energy efficiency, easy handling during storing and transporting. Also the studies have
concentrated on 2-propanol as an alcohol's fuel because it shows higher performance and a lower overpotential.
Alcohols with more than two carbon atoms have many isomers and special characteristics of non-CO
adsorption. Isopropanol is the smallest secondary alcohol molecule. It is of tremendous importance in
fundamental studies. The mechanism of 2-PrOH electro-oxidation reaction has been investigated by means of
electrochemical and spectroscopic techniques (in situ infrared spectroscopy),as well as online mass
spectroscopy [2-4]. According to these investigations, it is observed that acetone is the main electro-oxidation
product of 2-PrOH. No dissociative adsorption of 2-PrOH was found by in situ infrared spectra. Acetone acts
both the role of product and intermediate, and that the formation of a further oxidized product, CO2, was also
observed. Although the mechanisms and kinetics of 2-propanol oxidation are comparatively well described
using platinum electrodes, but there are very few reports on electrochemical oxidation of 2-PrOH on bimetallic
electrodes. Some of the investigations showed that binary electrodes exhibit better electrocatalytic activity for
isopropanol oxidation [5-7]. Gonza?lez et al. investigated the electro-oxidation of 2-PrOH onto PtSn surface at
low potential. They observed that acetone is inert onto this surface [8]. Therefore, the objective of the present
investigation is to report the results of systematic studies on electro-oxidation of 2-PrOH onto graphite
Materials: Sulfuric acid (Merck), H2PtCl6 (Arrora Matthey Limited), SnCl2 (Merck) were used as
supplied. Isopropanol (Merck) was distilled before use. Electrode preparation: Graphite sheet (Alfa-Aesar) was considered as substrate for metals (Pt and Sn)
deposition. Before each deposition, the cleaning of graphite surface was done electrochemically. Depositions
were carried out galvanostatically (PAR VersaStatTMII) with a current density of 2.5mA.cm-2
from a mixed salt solution(Pt and Sn) bath.
Electrode characterization: The surface characterisation of the anode material was investigated with a
SEM ,scanning electron microscope (SEM, Hitachi S-3000N), at an accelerating potential of 20kV. The
elemental compositions of the electro-deposited catalyst was determined by EDX (energy dispersive X-ray)
analysis. The EDX analysis was performed using an EXLII, oxford attached to the microscope.
Electrochemical measurement: The activity of the deposited electrodes towards 2-PrOH oxidation was
studied by cyclic voltammetry technique (PAR VersaStatTMII). For this study, a three electrode setup was
constructed, where carbon supported electrodes (1cm x 1 cm) were the working electrodes, Pt foil (1cm2
) was
the counter electrode, while a saturated calomel electrode (SCE) acted as reference electrode. The electrolytes
were 0.5 M H2SO4 acid solution (blank), and 0.5 M H2SO4 containing 2-PrOH (1.0M) solution. Cyclic
voltammograms of the blank solution and alcohol solutions were recorded between -0.2 to 1.1 V vs. SCE. All
the experiments were carried out at 250C.
SEM image of the PtSn electrode surface is presented in figure 1. It is seen that the bimetallic electrode
is covered with a uniform, relatively smooth catalyst layer. Here the SEM images do not give much information
on particle size and its growth kinetics, but a uniform growth of relatively smooth catalyst layer is observed.
The energy dispersion X-ray (EDX) spectrums of the electrode is given in figure 2. It is seen from the
spectrum that peaks at about 1.6, 2.2, 8.3, 9.4, 10, 11 and 13keV with a strong intensity peak at 2.2 keV are
observed for metallic Pt which matches with the literature values. Tin peaks come at about 3.0 and 3.5 keV.
Table 1 shows the bath composition and EDX composition.
The standard reduction potential (SHE) of the species involved in the electro-deposition of Pt, Sn are
[PtCl6]
2-
/ [PtCl4]
2- = 0.68 V,[PtCl4]
2-
/Pt = 0.76 V, Sn2+/Sn = -0.14 V.
From the above potential values, it is seen that in the course of co-deposition, the possibility of
reduction of tin precursors to metallic Sn is lower as compared to that of Pt. EDX results support the above
supposition. Thus based on the composition obtained from EDX analysis of the electrode, the electrode may be
Cyclic voltammogram(CV) of the blank solution presented in figure 3. This CV does not exhibit any
typical hydrogen desorption/ adsorption peaks. The current slowly increases from 0.280 V and a peak appears at
about 0.51 V. This may be due to tin oxide formation.The figure 4 illustrates the cyclic voltammogram profiles of isopropanol electrooxidation onto
Pt86Sn14working electrode at different scan rates within the potential limit -0.2 to 1.1V vs. SCE. Two anodic
oxidation peaks are observed during the potential sweep towards higher potential and one oxidation peak
appears during reverse scan. In case of, Pt86Sn14 current increases from 0.12 V and the first peak appears at 0.3V
followed by a 2nd peak appears at about 0.7 V.The appearance of two oxidation peaks on the forward scan can
be described to the oxidation of the fuel by two kinds of chemisorbed oxygen species. It is also observed that
anodic peak potential as well as the corresponding anodic peak currents has been changed with scan rate. An
increase in scan rate increases the peak current and shifts the peak potential in the positive direction.
Galvanostatic PtSn Electrode Prep on Graphite for Electrooxidation Study. (2019, Nov 30). Retrieved from https://studymoose.com/jou-example-essay
👋 Hi! I’m your smart assistant Amy!
Don’t know where to start? Type your requirements and I’ll connect you to an academic expert within 3 minutes.
get help with your assignment
