I tried to measure the CV of commercial Pt/C (20wt%) by loading on an ITO glass. The Pt/C was loaded in a condition of an ink with Nafion and 2-propanol.
I used three electrode system, which is composed of CE = Pt plate, RE = Ag/AgCl, WE = Pt/C loaded ITO glass.
The electrochemical test was performed with 0.5M H2SO4 at a scan rate of 30 mV/sec with a potential window from -0.2 to 1.0 V (vs. Ag/AgCl).
The result was as below:
(1) Current density decreases abruptly with the cycle continues (For example, 3rd cycle exhibits half of current density for the 2nd cycle)
(2) The loaded Pt/C was easily detached during the removal of WE from the dipped electrolyte.
In my opinion, it is believed that Pt/C is detached from the ITO glass after 1st cycle because there is no reason that the current density cannot be reduced with fast speed. Once I loaded the same ink on the glassy carbon electrode (GCE), there was no sudden decrease of current density.
Please let me know other possible reasons of the results stated above.
I feel these is no proper adhesion between ITO and Pt/C ink. And also that the ITO is not so conducting, if i am correct. Because I also do the same experiments but with Glassy carbon electrode as a substrate and we don't see any detachment of the ink even after 10,000 cycles. In your case you can coat a carbon layer first then coat the Pt/C ink with little higher amount of Nafion added in to it. You can also add some amount of Teflon solution for the adhesion. Plz be care full that dont add teflon much.
0.5 M H2SO4 does not sound good. At low pH ITO will dissolve.
You can check the surface by SEM.
Inorganic acids are generally used to etch ITO. I think 0.5 M sulfuric acid is etching your ITO layer and therefore Pt/C layer is also getting detached.
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