A 50 microL drop of 0.1M H2SO4 was placed on the screen printed electrodes (DRP110) and ten cyclic voltammograms from 0 to +1.25V were recorded, using a scan rate of 100 mV/s. Then the electrodes were washed with water. On the working electrode, an aliquot de 2 microL carbon nanofibers/DMF dispersion was placed. At the moment of the aliquot touched the working electrode, it spread all over. Without electrochemical cleanen, the aliquot is deposited on the working electrode very well. Any suggestions? Please, thanks.
Surface tension? 0.1M sulphuric acid will have a ST of ~70mN/m whereas DMF has an ST of 36.8 mN/m
I also think that. So I use a solvent to clean the electrode with a surface tension similar to the DMF?
Not sure, can you dab a tiny amount of surfactant onto the electrode or add it to the sulphuric acid, or will that complicate the experiment in other ways?
Which material is your screen-printed electrode made of?
From the description you make I make the guess that it is made of some type of carbon material. It that is the case, when you perform your CV with H2SO4 you are changing mos probably the surface from being more hydrophobic to being more hydrophylic. You can check this using some type of contact angle measurements.
I also guess, that you want to clean your electrode to have more reproducible results. Because it is a screen-printed electrode you do not have so many ways to "clean" your electrode besides electrochemical cleaning. You might try plasma cleaning but this will also make your electrode more hydrophylic. My suggestion is that you change the solvent containing your carbon nanofibers to other solvent that fits better with the hydrophylicity of your clean surface.
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